WO2018137034A1

WO2018137034A1 - Apparatus and method for wastewater treatment

Info

Publication number: WO2018137034A1
Application number: PCT/CA2018/050089
Authority: WO
Inventors: Étienne BOUTET; Serge BAILLARGEON; Frederic ALLAIRE; Félix LIDA; Dominique CLAVEAU-MALLET; Yves Comeau
Original assignee: Bionest Technologies Inc.
Priority date: 2017-01-25
Filing date: 2018-01-25
Publication date: 2018-08-02

Abstract

An apparatus for treating wastewater, the apparatus comprising: a treatment chamber for treating wastewater to reduce a phosphorus content in the wastewater; and a pH modulation chamber for treating an effluent of the treatment chamber to modulate the pH of the effluent. The treatment chamber is configured to house iron and/or calcium oxide material for contacting the wastewater in use to treat the wastewater, and has an inlet for receiving the wastewater and an outlet for allowing the treated wastewater effluent to flow out of the treatment chamber and into the pH modulation chamber. The pH modulation chamber is configured to treat the treated wastewater effluent from the treatment container with a carbon dioxide to modulate its pH, and having an outlet for the pH modulated effluent to flow out of the pH modulation chamber.

Description

APPARATUS AND METHOD FOR WASTEWATER TREATMENT

CROSS-REFERENCE TO RELATED APPLICATION

[001] The present application claims priority to U.S. Patent Application No. 62/450,210, filed January 25, 2017, entitled "APPARATUS AND METHOD FOR WASTEWATER TREATMENT", which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

[002] The present disclosure relates to apparatus and methods for wastewater treatment, specifically but not exclusively to apparatus and methods for reducing a phosphorus content in the wastewater.

BACKGROUND

[003] Methods for treating wastewater typically involve the separation of floating and settleable materials from the wastewater by sedimentation, followed by a reduction in the organic matter content using for example a biochemical process which converts carbonaceous matter to carbon dioxide and biomass. The resultant treated wastewater can then be discharged into the environment.

[004] However, the resultant treated wastewater may still contain high levels of phosphorus with harmful effects on the environment. Regulations set by many developed countries now stipulate a phosphorus content in treated wastewater of less than 1 mg/litre of phosphorus before release into the environment. Municipal wastewater, for example, may have 5 to 20 mg/1 of total phosphorous levels before treatment.

[005] One existing method for lowering phosphorus content in wastewater is chemical precipitation of phosphorus and its removal as a solid from the wastewater. Chemicals such as Ca(OH)₂ (lime), alum or ferric chloride/sulphate and ferrous sulphate are used in such chemical precipitation methods. [006] However, these methods require careful dosing and monitoring of the chemicals and the effluent. The chemicals can cause clogging of pipes and pumps and require an operator for maintenance. Furthermore, safety procedures must be put into place for the safe handling of chemicals. Finally, a settling tank is required to remove the phosphorus precipitates. These methods are unsuitable for residential phosphorus treatment of wastewater.

[007] Another method for phosphorus content removal is electrocoagulation. Instead of using chemicals for forming phosphorus precipitates, an electrical charge is applied to the wastewater through anode/cathodes causing release of metal cations and phosphorus precipitates which can then be removed from the wastewater through settling. As with chemical phosphorus removal, this is a method that requires safety procedures and maintenance, and again is unsuitable for residential applications.

[008] Therefore, there is a need for a system and/or method for wastewater treatment which addresses the abovementioned limitations.

SUMMARY [009] It is an object of the present to ameliorate at least some of the limitations present in the prior art.

[010] From a broad aspect, there is provided an apparatus for treating wastewater, the apparatus comprising: a treatment chamber for treating wastewater to reduce a phosphorus content in the wastewater; and a pH modulation chamber for treating an effluent of the treatment chamber to modulate the pH of the effluent; the treatment chamber being configured to house iron and/or calcium oxide material for contacting the wastewater in use to treat the wastewater, and having an inlet (treatment inlet) for receiving the wastewater, and an outlet (treatment outlet) for allowing the treated wastewater effluent to flow out of the treatment chamber and into the pH modulation chamber; the pH modulation chamber being configured to treat the treated wastewater effluent from the treatment container with carbon dioxide (also referred to as carbon dioxide gas or carbon dioxide enriched air) to modulate its pH, and having an outlet (pH modulation chamber outlet) for the pH modulated effluent to flow out of the pH modulation chamber. [Oi l] In certain embodiments, the treatment chamber comprises (is defined by) a treatment container. The treatment container is selectively fluidly sealable to separate the iron and/or calcium oxide material from the carbon dioxide of the modulation chamber. The pH modulation chamber may be arranged to house the treatment container. In these embodiments, the pH modulation chamber can be considered as an outer chamber and the treatment container as an inner chamber. The treatment container may be removeably housed in the pH modulation chamber such that the treatment container can be removed from the pH modulation chamber. The pH modulation chamber may comprise an opening defined in a wall of the pH modulation chamber, the opening being sized and shaped to allow removal of the treatment container therethrough. The opening may be sized and shaped to allow removal of a single treatment container at a time. Removal and/or replacement of the treatment container may be required for maintenance (e.g. in the case of clogging of the iron and/or calcium oxide material), and/or to provide a fresher supply of the iron and/or calcium oxide material. Alternatively, instead of the treatment container being removeable from the pH chamber, the treatment container or the treatment chamber may have a removeable liner for housing the iron and/or calcium oxide material. The treatment container may comprise at least one column or at least one row for receiving the removeable liner.

[012] In certain embodiments, the treatment chamber comprises a plurality of treatment containers. Each treatment container may be selectively fluidly sealable to separate the iron and/or calcium oxide material from the carbon dioxide of the modulation chamber. The pH modulation chamber may be arranged (e.g. sized and shaped) to house the plurality of treatment containers. For example, there may be two rows of five treatment containers. The plurality of treatment containers, such as in one row, may be fluidly connectable in series for wastewater to flow in sequence from a first treatment container of the plurality of treatment containers to a last treatment container of the plurality of treatment containers, the last treatment container having the outlet for allowing the treated wastewater effluent to flow out of the treatment container and into the pH modulation chamber. The outlet of the last treatment chamber may be fluidly communicable with the pH modulation chamber. The treatment containers of the plurality of treatment containers, other than the last treatment container, each have an outlet which is fluidly connected to another one of the plurality of treatment containers, such as to the inlet of the another one of the plurality of treatment containers in the series. In another embodiment, the plurality of treatment containers can be arranged so that the outlet of each of the plurality of treatment containers is fluidly connected to the pH modulation chamber, and not to the inlet of another treatment container. In this embodiment, wastewater contacts the calcium and/or iron oxide material of a single treatment container before contacting the carbon dioxide in the pH modulation chamber for pH modulation (also referred to as parallel treatment). This is in contrast to the earlier described embodiment where the treatment containers are connected in series and the wastewater consecutively contacts the calcium and/or iron oxide material of the plurality of treatment containers before contacting the carbon dioxide for pH modulation (also referred to as series treatment). [013] In certain embodiments, at least one treatment container of the plurality of treatment containers contains calcium and/or iron oxide material having an average particle size which is larger than an average particle size of calcium and/or iron oxide material contained in another one of the plurality of treatment containers which is positioned downstream of the at least one treatment container of the plurality of treatment containers. The plurality of the treatment containers may be connected in series such that the outlet of at least one of the treatment containers is fluidly connected to the inlet of another of the treatment containers in the plurality of treatment containers. In other words, during treatment, wastewater contacts larger size particles before contacting the smaller size particles. This can help to avoid clogging of the more reactive particles. In certain embodiments, at least two of the treatment containers of the plurality of treatment containers contain particles of iron and/or calcium oxide material having a different average particle size than one another. In certain embodiments, an average particle size of the iron and/or calcium oxide material decreases between the first and last treatment containers. For example, the first two treatment containers of the plurality of treatment containers may comprise a larger average particle size of calcium and/or iron oxide material than the subsequent three treatment containers in the series.

[014] In certain embodiments, there are a plurality of treatment containers and at least one of the treatment containers upstream comprise calcium and/or iron oxide particles having an average particle size which is larger than in another one of the plurality of treatment containers which is downstream of the at least one of the treatment containers so that as wastewater flows through the plurality of treatment containersit contacts the average larger particle size particles before the smaller particle size particles.

[015] In certain embodiments, the treatment container and/or at least one of the plurality of treatment containers is individually moveable within the pH modulation chamber. The apparatus may comprise a transportation system for moving the treatment container and/or the at least one of the plurality of treatment containers within the pH modulation chamber. The transportation system may comprise a wheeled platform for supporting the treatment container and/or at least one of the plurality of the treatment containers, the wheeled platform being moveable along a floor of the pH modulation chamber. The transportation system may further comprise at least one pulley and a cable attachable at one end to the wheeled platform and threaded through the pulley to pull the wheeled platform using the other end of the cable. The transportation system may further comprise a track for guiding the movement of the wheeled platform.

[016] In certain embodiments, the apparatus further comprises a lifting assembly, the lifting assembly comprising a support structure engageable with lifting equipment and having a connector engageable with the treatment container and/or at least one of the plurality of treatment containers. The connector may comprise an arm or a rod extendable into the treatment chamber and/or at least one of the plurality of treatment containers through an opening of the treatment chamber and attachable to a plate. The arm or rod may comprise a metal wire, such as a stainless steel wire. The plate may have a dimension, such as a diameter, smaller than a dimension, such as a diameter, of the opening of the treatment container. In use, the plate is positioned beneath the calcium and/or iron oxide material in the treatment container and the arm/or extends through the calcium and/or iron oxide material. The support structure may comprise a hook of the lifting equipment. Alternatively, the connector may comprise arms extendable from the support structure and attachable to an outside of the treatment chamber and/or at least one of the plurality of treatment containers or the wheeled platform. In certain embodiments, each arm comprises metal wire such as a stainless steel wire.

[017] In certain embodiments, the apparatus further comprises an inlet ("carbon dioxide inlet") for supplying carbon dioxide to the pH modulation chamber. The inlet may be fluidly connectable to a bioreactor which is arranged to treat carbonaceous matter in wastewater and which generates carbon dioxide as a by-product. The apparatus may further comprise a wastewater inlet for providing wastewater to the apparatus. The wastewater inlet may be fluidly connected to the treatment container. The apparatus may further comprise a bioreactor fluidly connected to the apparatus for supplying the wastewater and optionally the carbon dioxide. In embodiments where there are a plurality of treatment containers having a "parallel" treatment configuration (i.e. effluent from each treatment container flows into the pH modulation chamber), the wastewater inlet may be directly connected to each of the treatment container inlets. In embodiments where there are a plurality of treatment containers having a "series" treatment configuration (i.e. effluent from each treatment container, except the last treatment container of the series, flows into the next treatment container of the series) the wastewater inlet may be directly connected to only the first treatment container of the plurality of treatment containers. In certain embodiments, the wastewater inlet may be fluidly connectable to a bioreactor to receive the effluent therefrom. The bioreactor may be the same bioreactor that supplies carbon dioxide to the apparatus. A pump may be provided for pumping the wastewater to the wastewater inlet. A reservoir may be provided for receiving the effluent from the bioreactor and which is fluidly connected to the apparatus.

[018] In certain embodiments, the calcium oxide and/or iron oxide material has an alkaline pH. In certain embodiments, the calcium oxide and/or iron oxide material is alkaline calcium oxide material. In certain embodiments, the calcium oxide and/or iron oxide material comprises steel slag. Slag contains mixtures of metal oxides which at high pH can cause conversion of dissolved phosphorus into a solid form through various mechanisms such as adsorption of phosphorus onto the metal oxide surface as well as precipitation. The calcium and/or iron oxide material may comprise particles of more than about 2 mm diameter and less than about 20 mm in diameter, from about 2 mm to about 10 mm in diameter, from about 2 mm to about 15 mm in diameter. In certain embodiments, the calcium and/or iron oxide material comprises particles ranging from about 2 to about 10 mm in diameter. The particles may comprise fine particles having an average diameter from about 2 to about 4 mm, or 3 to about 5mm and coarse particles having an average diameter from about 5 to about 10 mm. In certain embodiments, the treatment chamber or the treatment container also houses inert particles, such as gravel. In certain embodiments, the treatment chamber or the treatment container also houses particles having an average particle size of about 10-20 mm in diameter. These particles may be gravel or another inert particle, or calcium oxide and/or iron oxide material. In certain embodiments, the treatment container or treatment chamber comprises at least two layers of the calcium and/or iron oxide material, and optionally the inert material. For example, the treatment container may comprise a bottom layer of particles having an average particle size of about 10-20mm in diameter (e.g. inert particles or slag particles), followed by a layer of particles having an average particle size of about 5-10 mm in diameter (e.g. the particles being calcium and/or iron oxide material) followed by a layer of particles having an average particle size of about 3-5mm in diameter (e.g. the particles being calcium and/or iron oxide material) The inventors have found that placing such larger particles upstream in the treatment chamber or the treatment container, such as proximate a flow distributor discharge ends, can help with fluid distribution and avoid or minimize clogging.

[019] In certain embodiments, the treatment container or at least one of the plurality of treatment containers has an atmospheric vent for allowing gaseous flow out of the treatment container and for restricting gaseous flow into the treatment container, and optionally an outlet valve for preventing carbon dioxide gas flow from the pH modulation chamber into the treatment container. In certain embodiments in which there are a plurality of treatment containers, the atmospheric vent is directly fluidly connected to each treatment container. In certain embodiments in which there are a plurality of treatment containers, the atmospheric vent is fluidly connected to a common ventilation pipe which is fluidly communicates with each treatment container. [020] In certain embodiments, the treatment chamber, treatment container or at least one of the plurality of treatment containers comprises a flow distributor at the inlet, proximate the inlet, or downstream of the inlet for distributing the flow of wastewater into the treatment container. In certain embodiments, the outlet of the treatment container, treatment chamber or at least one of the plurality of treatment containers is near a top of the treatment container, treatment chamber or the at least one of the plurality of treatment containers. In certain embodiments, the inlet of the treatment container, treatment chamber or at least one of the plurality of treatment containers is near a bottom of the treatment container, treatment chamber or the at least one of the plurality of treatment containers. In certain embodiments, the inlet is at a lower height than the outlet of the treatment container, treatment chamber or at least one of the plurality of treatment containers. [021] In certain embodiments, the treatment chamber, treatment container or at least one of the plurality of treatment containers comprises at least two compartments in fluid communication with one another, each of the at least two compartments being configured to house the iron and/or calcium oxide material. The apparatus may further comprise at least one baffle for forming the two compartments.

[022] From another aspect, there is provided an apparatus for treating wastewater, the apparatus comprising: an inner chamber in fluid communication with an outer chamber; the inner chamber being configured to house iron and/or calcium oxide material for treating wastewater to reduce a phosphorus content in the wastewater; and the outer chamber being configured to house a pH modulator for modulating the pH of the inner chamber effluent. In certain embodiments of this aspect, the pH modulator is an acid or carbon dioxide. The pH modulator may be carbon dioxide and the outer chamber may have a carbon dioxide inlet fluidly connectable to a bioreactor comprising a source of carbonaceous matter to provide the source of carbon dioxide. In certain embodiments, the inner chamber is defined by (comprises) a treatment container. The treatment container may be selectively fluidly sealable to separate the iron and/or calcium oxide material housed therein from the pH modulator of the outer chamber. In certain embodiments, the outer chamber is defined by (comprises) a pH modulation chamber. The pH modulation chamber may have an opening defined in a wall of the pH modulation chamber, the opening being sized and shaped to allow removal of the treatment container or a removeable liner containing the iron and/or calcium oxide material therethrough. In certain embodiments, the inner chamber comprises a plurality of treatment containers, which may be arranged as one or more rows of treatment containers in the pH modulation chamber. Two rows of five treatment containers may be provided. The plurality of treatment containers may be connected in "series" or have a "parallel" configuration, as described above. Optionally the inner and outer chambers are housed in a housing.

[023] From yet another aspect, there is provided an apparatus for treating wastewater, the apparatus comprising: a phosphorus treatment chamber for treating wastewater to reduce a phosphorus content in the wastewater, and a pH modulation chamber for treating an effluent of the treatment container to modulate the pH of the effluent; the phosphorus treatment chamber comprising a treatment container configured to house iron and/or calcium oxide material for contacting the wastewater in use to treat the wastewater, an inlet for receiving the wastewater, and an outlet for allowing the treated wastewater effluent to flow out of the treatment container; the pH modulation chamber being configured to house the treatment container and to treat the treated wastewater effluent from the treatment container with a carbon dioxide gas to modulate its pH, and an outer chamber outlet for allowing the pH modulated treated wastewater to flow out of the outer chamber. In certain embodiments of this aspect, the inner chamber is defined by a plurality of treatment containers, optionally fluidly connected in a series or having a parallel configuration, and the outer chamber is defined by a pH modulation chamber, the pH modulation chamber having an opening defined in a wall of the pH modulation chamber, the opening being sized and shaped to allow removal of the treatment container, the plurality of treatment containers being moveable in the pH modulation chamber with respect to the opening for removal of the plurality of treatment containers through the opening. In certain embodiments, an average particle size of a first portion of the iron and/or calcium oxide particles is relatively larger than an average particle size of a second portion of the iron and/or calcium oxide particles which is downstream of the first portion.

[024] From a further aspect, there is provided an apparatus for treating wastewater, the apparatus comprising: a treatment chamber for treating wastewater to reduce a phosphorus content in the wastewater, and a pH modulation chamber for treating an effluent of the treatment chamber to modulate the pH of the effluent, the treatment chamber and the pH modulation chamber being in fluid communication with one another to allow wastewater to flow from the treatment chamber to the pH modulation chamber; the treatment chamber being configured to house iron and/or calcium oxide material for treating the wastewater to reduce a phosphorus content in the wastewater; the pH modulation chamber being configured to allow contact of the effluent from the treatment chamber with carbon dioxide gas in the pH modulation chamber for modulating the pH of the treatment chamber effluent, the pH modulation chamber having a carbon dioxide inlet fluidly connectable to a bioreactor comprising a source of carbonaceous matter in fluid communication with the pH modulation chamber to provide the source of carbon dioxide. In other words, the bioreactor is arranged to treat carbonaceous matter and to generate carbon dioxide as a by-product. In certain embodiments of this aspect, the treatment chamber is defined by a treatment container and the pH modulation chamber is arranged to house the treatment container. In certain embodiments, the pH modulation chamber has an opening defined in a wall of the pH modulation chamber, the opening being sized and shaped to allow removal of the treatment container or a removeable liner containing the iron and/or calcium oxide material therethrough. In certain embodiments, the treatment chamber is defined by a plurality of treatment containers fluidly connected in a series, and the pH modulation chamber has an opening defined in a wall of the pH modulation chamber, the opening being sized and shaped to allow removal of the treatment container, the plurality of treatment containers being moveable in the pH modulation chamber with respect to the opening for removal of the plurality of treatment containers through the opening. In certain embodiments, an average particle size of a first portion of the iron and/or calcium oxide particles is relatively larger than an average particle size of a second portion of the iron and/or calcium oxide particles which is downstream of the first portion.

[025] From a yet further aspect, there is provided an apparatus for treating wastewater, the apparatus comprising: a treatment chamber for treating wastewater to reduce a phosphorus content in the wastewater, and a pH modulation chamber for treating an effluent of the treatment chamber to modulate the pH of the effluent, the treatment chamber and the pH modulation chamber being in fluid communication with one another to allow wastewater flow from the treatment chamber to the pH modulation chamber; the treatment chamber being configured to house iron and/or calcium oxide particles for treating the wastewater to reduce a phosphorus content in the wastewater; and the pH modulation chamber being configured to allow contact of the effluent from the treatment container with a pH modulator in the pH modulation chamber for modulating the pH of the treatment chamber effluent, wherein an average particle size of a first portion of the iron and/or calcium oxide particles is relatively larger than an average particle size of a second portion of the iron and/or calcium oxide particles which is downstream of the first portion. In certain embodiments, the pH modulator is carbon dioxide or any other carbon source. The pH modulation chamber may have a carbon dioxide inlet fluidly connectable to a bioreactor comprising a source of carbonaceous matter for providing the carbon dioxide to the pH modulation chamber. In certain embodiments, the treatment chamber is defined by a treatment container fluidly communicable in use with the pH modulation chamber only through a wastewater outlet of the treatment container. In certain embodiments, the treatment chamber is defined by a treatment container and the pH modulation chamber is arranged to house the treatment container. The pH modulation chamber may have an opening defined in a wall of the pH modulation chamber, the opening being sized and shaped to allow removal of the treatment container or a removeable liner containing the iron and/or calcium oxide material therethrough. In certain embodiments, the treatment chamber is defined by a plurality of treatment containers optionally fluidly connected in a "series" or in "parallel", and the pH modulation chamber has an opening defined in a wall of the pH modulation chamber, the opening being sized and shaped to allow removal of the treatment container, the plurality of treatment containers being moveable in the pH modulation chamber with respect to the opening for removal of the plurality of treatment containers through the opening.

[026] From another aspect, there is provided an apparatus for treating wastewater, the apparatus comprising: a plurality of treatment containers for treating wastewater to reduce a phosphorus content in the wastewater; and an outer chamber for housing the plurality of treatment containers and for treating an effluent of the plurality of treatment containers to modulate the pH of the wastewater; each treatment container of the plurality of treatment containers being configured to house iron oxide and/or calcium oxide material for contacting the wastewater in use to treat the wastewater, and having an inlet for receiving the wastewater to be treated, and an outlet for the treated wastewater effluent; the plurality of the treatment containers being fluidly connectable in series for wastewater to flow in sequence from a first treatment container of the plurality of the treatment containers to a last treatment container of the plurality of the treatment containers, the outlet of the last treatment container being fluidly communicable with the outer chamber; the outer chamber being configured to house carbon dioxide gas for contacting the treated wastewater effluent to modulate its pH, and an outer chamber outlet for allowing the pH modulated treated wastewater effluent to flow out of the outer chamber.

[027] From a yet further aspect, there is provided a method for treating wastewater, the method comprising: providing wastewater to be treated to a treatment container having iron oxide and/or calcium oxide material therein; allowing contact of the wastewater with the iron oxide and/or calcium oxide material to treat the wastewater to lower a phosphorus content in the wastewater; allowing the effluent to flow out of the treatment container and into an outer chamber in which the treatment container is housed for contact with carbon dioxide in the outer chamber to modulate the pH of the effluent; allowing the pH modulated treated wastewater to flow out of the outer chamber. [028] In certain embodiments of any of the above aspects or embodiments, the treatment container or at least one of the plurality of treatment containers is individually moveable within the pH modulation chamber. The apparatus may further comprise a transportation system for moving the treatment container or at least one of the plurality of treatment containers within the pH modulation chamber such as a wheeled platform for supporting the treatment container, the wheeled platform being moveable along a floor of the pH modulation chamber. The transportation system may further comprise at least one pulley and a cable attachable at one end to the wheeled platform and threaded through the pulley to pull the wheeled platform using the other end of the cable. The transportation system may further comprise a track for guiding the movement of the wheeled platform.

[029] In certain embodiments of any of the above aspects or embodiments, the apparatus further comprises a lifting assembly, the lifting assembly comprising a support structure engageable with lifting equipment and having a connector engageable with the treatment container or at least one of the plurality of treatment containers. The connector may comprise an arm or a rod extendable into the treatment container through an opening and attachable to a plate. The arm or rod may comprise a metal wire, such as a stainless steel wire. The plate may have a dimension, such as a diameter, smaller than a dimension, such as a diameter, of the opening of the treatment container. In use, the plate is positioned beneath the calcium and/or iron oxide material in the treatment container and the arm/or extends through the calcium and/or iron oxide material. Alternatively, the connector may comprise arms extendable from the support structure and attachable to an outside of the treatment chamber, the treatment container or the wheeled platform. Each arm may comprise a metal wire, such as a stainless steel wire.

[030] In certain embodiments of any of the above aspects or embodiments, the calcium oxide and/or iron oxide material comprises steel slag. The calcium and/or iron oxide material may comprise particles of more than about 2 mm diameter and less than about 20 mm in diameter, from about 2 mm to about 15 mm in diameter, or from about 2 mm to about 10 mm in diameter. The calcium and/or iron oxide material may comprise particles ranging from about 2 to about 10 mm in diameter, from about 2 to about 4 mm, about 3 mm to about 5 mm in diameter, and/or from about 5 to about 10 mm in diameter, and combinations of these size ranges. [031] In certain embodiments of any of the above aspects or embodiments, the treatment chamber, the treatment container or at least one of the plurality of treatment containers has an atmospheric vent for allowing gaseous flow out of the inner chamber, the treatment chamber or the treatment container and for restricting gaseous flow into the inner chamber, treatment chamber or the treatment container. An outlet valve may be provided for preventing carbon dioxide (gas) flow from the pH modulation chamber into the treatment container or the treatment chamber. The outlet valve may be positioned at the wastewater outlet of the treatment container.

[032] In certain embodiments of any of the above aspects or embodiments, the inner chamber, the treatment chamber, the treatment container or at least one of the plurality of treatment containers comprises a flow distributor at the inlet for distributing the flow of wastewater in the treatment container.

[033] In certain embodiments of any of the above aspects or embodiments, the inner chamber, the treatment chamber or the treatment container comprises at least two compartments in fluid communication with one another, each of the at least two compartments being configured to house the iron and/or calcium oxide material. The apparatus may further comprise at least one baffle for forming the two compartments.

[034] From another aspect, there is provided a method for treating wastewater, the method comprising: providing wastewater to be treated to a treatment chamber having iron oxide and/or calcium oxide material therein; allowing contact of the wastewater with the iron oxide and/or calcium oxide material to treat the wastewater to lower a phosphorus content in the wastewater; providing the effluent from the treatment chamber to a pH modulation chamber for contact with carbon dioxide to modulate the pH of the effluent; allowing the pH modulated treated wastewater to flow out of the pH modulation chamber. In certain embodiments, the pH modulation chamber comprises an outer chamber and the treatment chamber comprises a treatment container which is selectively fluidly sealable to separate the iron oxide and/or calcium oxide material from the carbon dioxide of the pH modulation chamber. [035] From another aspect, there is provided a method for treating wastewater, the method comprising: providing wastewater to be treated to an inner chamber of a wastewater apparatus, the inner chamber housing iron oxide and/or calcium oxide material therein; allowing contact of the wastewater with the iron oxide and/or calcium oxide material to treat the wastewater to lower a phosphorus content in the wastewater; providing the effluent from the inner chamber into an outer chamber, in which the treatment container is housed, for contact with a pH modulator in the outer chamber to modulate the pH of the inner chamber effluent, optionally the pH modulator being carbon dioxide; and allowing the pH modulated treated wastewater to flow out of the outer chamber. [036] From a further aspect, there is provided a method for treating wastewater, the method comprising: providing wastewater to be treated to a treatment chamber for reducing a phosphorus content in the wastewater, the treatment chamber housing iron and/or calcium oxide particles; allowing the effluent from the treatment chamber to flow into a pH modulation chamber, the pH modulation chamber having a pH modulator therein for modulating the pH of the treatment chamber effluent, optionally the pH modulator being carbon dioxide; allowing the pH modulated treated wastewater to flow out of the pH modulation chamber, wherein an average particle size of a first portion of the iron and/or calcium oxide particles is relatively larger than an average particle size of a second portion of the iron and/or calcium oxide particles, the second portion being downstream of the first portion. [037] In certain embodiments, the calcium oxide and/or iron oxide material comprises steel slag.

[038] In certain embodiments, the iron oxide and/or calcium oxide material comprises particles ranging from about 2 to about 10 mm in diameter, particles ranging from about 2 to about 4 mm in diameter, particles ranging from about 3 to about 5 mm in diameter and/or particles ranging from about 5 to about 10 mm in diameter

[039] In certain embodiments, the treatment container, inner chamber or treatment chamber also houses inert particles, the inert particles optionally having a particle size of about 10-20 mm in diameter, or particles of calcium and/or iron oxide material having an average particle size of about 10-20 mm in diameter. [040] In certain embodiments, the method comprises allowing the wastewater to be treated to contact larger sized iron oxide and/or calcium oxide particles before contacting smaller sized iron oxide and/or calcium oxide particles.

[041] In certain embodiments, the pH modulator is carbon dioxide, the method further comprising supplying carbon dioxide from a bioreactor. In certain embodiments, the method further comprises supplying the wastewater to be treated from a bioreactor.

[042] In certain embodiments, the wastewater to be treated is supplied at or near a bottom of the treatment container, inner chamber or treatment chamber, and the wastewater is allowed to flow upwardly through the iron oxide and/or calcium oxide material towards an outlet of the treatment container, inner chamber or treatment chamber.

[043] In certain embodiments, the treatment chamber or the inner chamber comprise a treatment container which is selectively fluidly sealable to separate the iron oxide and/or the calcium oxide material from the pH modulator.

[044] In certain embodiments, the method comprises providing a plurality of treatment containers and supplying the wastewater to be treated into each treatment container of the plurality of treatment containers from a wastewater inlet of the apparatus, or from an outlet of one of the treatment containers of the plurality of treatment containers.

[045] In certain embodiments, the method further comprises providing a plurality of treatment containers and ventilating each one of the plurality of treatment containers through a common ventilation pipe or through individual ventilation pipes.

[046] In certain embodiments, the method further comprises moving a treatment container or treatment chamber proximate an opening in a roof of the outer compartment or the pH modulation chamber using a wheeled platform supporting the treatment container or treatment chamber to be removed. [047] In certain embodiments, the method further comprises engaging the treatment container and/or the wheeled platform with a lifting assembly; and lifting the treatment container and/or the wheeled platform out of the opening in the outer chamber. The method may further comprise guiding the wheeled platform using a track associated with the outer compartment.

[048] From another aspect there is provided a method for treating wastewater, the method comprising: providing wastewater to be treated to a plurality of treatment containers fluidly connected in series, allowing the wastewater to flow in sequence from a first treatment container of the plurality of the treatment containers to a last treatment container of the plurality of the treatment containers, the outlet of the last treatment container being fluidly communicable with an outer chamber in which the plurality of treatment containers are housed; at each treatment container of the plurality of treatment containers, allowing contact of the wastewater with iron oxide and/or calcium oxide material contained therein to treat the wastewater to lower a phosphorus content in the wastewater; allowing the effluent to flow out of the last treatment container and into an outer chamber in which the treatment container is housed for contact with carbon dioxide in the outer chamber to modulate the pH of the effluent; allowing the pH modulated treated wastewater to flow out of the outer chamber. [049] From another aspect, there is provided a method for treating wastewater, the method comprising: allowing wastewater to contact iron oxide and/or calcium oxide material to lower a phosphorus content of the wastewater; and modulating the pH of the wastewater treated by the iron oxide and/or calcium oxide material; wherein the iron oxide and/or calcium oxide material comprises particles and a first portion of the particles has an average particle size which is relatively larger than an average particle size of the a second portion of the particles, the second portion being downstream of the first portion.

[050] From a further aspect, there is provided a method for treating wastewater, the method comprising: allowing wastewater to contact iron oxide and/or calcium oxide material in an inner chamber of a wastewater treatment apparatus to lower a phosphorus content of the wastewater; and modulating the pH of the wastewater treated by the iron oxide and/or calcium oxide material in an outer chamber of the apparatus; wherein the inner chamber is housed within the outer chamber and fluidly connectable thereto. In certain embodiments, the method comprises restricting fluid flow from the outer chamber to the inner chamber. In certain embodiments, the method comprises restricting fluid flow from an atmosphere outside of the apparatus into the inner chamber.

[051] From a yet further aspect, there is provided a method for treating wastewater, the method comprising: allowing wastewater to contact iron oxide and/or calcium oxide material in a treatment chamber of a wastewater treatment apparatus to lower a phosphorus content of the wastewater; and modulating the pH of the wastewater treated by the iron oxide and/or calcium oxide material in a pH modulation chamber of the apparatus; wherein the iron oxide and/or calcium oxide material is removeable from the treatment chamber, or the treatment chamber is removeable from the apparatus. In certain embodiments, the method comprises restricting fluid flow from the pH modulation chamber to the treatment chamber. In certain embodiments, the method comprises restricting fluid flow from an atmosphere into the treatment chamber. In certain embodiments, the treatment chamber is a treatment container which is removeably fluidly connectable to the pH modulation chamber. In certain embodiments, the treatment chamber comprises at least one removeable liner for housing the calcium oxide and/or iron oxide material. [052] In certain embodiments, the calcium oxide and/or iron oxide material comprises steel slag. The calcium and/or iron oxide material may comprise particles of more than about 2 mm diameter. The calcium and/or iron oxide material may comprise particles ranging from about 2 mm in diameter to about 10 mm in diameter, from about 2 to about 3 mm in diameter, from about 3 to about 5 mm in diameter, or from 5 to about 10 mm in diameter. [053] In certain embodiments, the method further comprises allowing the wastewater to be treated to contact coarse sized iron oxide and/or calcium oxide particles (e.g. from about to about 10 mm in diameter) before contacting finer sized iron oxide and/or calcium oxide particles (e.g. from about 2 to about 3 mm diameter), the coarse sized particles being larger than the fine sized particles. The coarse and fine particles may be contained in the same treatment container, treatment chamber or inner chamber, or in different treatment containers, treatment chambers or inner chambers.

[054] In certain embodiments, the source of the carbon dioxide is the by-product from biological treatment of wastewater. In certain embodiments, the method further comprises supplying the carbon dioxide gas from an outlet of a bioreactor. [055] In certain embodiments, the method further comprises supplying the carbon dioxide gas proximate a bottom of the outer chamber or the pH modulation chamber and allowing it to contact, in the outer chamber or pH modulation chamber, the wastewater effluent from the inner chamber, treatment chamber or treatment container. [056] In certain embodiments, the method further comprises supplying the wastewater to be treated near a bottom of the treatment container, inner chamber or treatment chamber and allowing the wastewater to be treated to flow upwardly through the iron oxide and/or calcium oxide material in the treatment container, inner chamber or treatment chamber.

[057] In certain embodiments, the method further comprises moving a treatment container to be removed proximate an opening in a roof of the outer compartment using a wheeled platform supporting the treatment container to be removed.

[058] In certain embodiments, the method further comprises engaging the treatment container and/or the wheeled platform with a lifting assembly; and lifting the treatment container and/or the wheeled platform out of the opening in the outer chamber. The method may further comprise guiding the wheeled platform using a track associated with the outer compartment.

[059] In any of the above aspects and embodiments, instead of using a carbon dioxide gas to modulate the pH treated wastewater, any inorganic carbon can be used, including C0₂, HC0₃ and H₂C0₃.

[060] By means of certain aspects and embodiments of the present disclosure, the apparatus can be installed under ground or above ground. Embodiments of the apparatus with removable treatment containers can enable replacement of the slag or maintenance work without having to dig up the entire apparatus. Simple lifting apparatus may suffice and a minimal ground crew.

[061] Steel slag is a by-product of steel production, and is therefore readily available and inexpensive, as well as being effective at phosphorus removal and non-toxic. [062] Carbon dioxide enriched air from a bioreactor as a by-product of conversion of the organic matter in the wastewater by the biomass can provide a continuous source of a pH modulator and which does not require access into the apparatus. As a pH modulator, carbon dioxide may be easier to manage than acidic pH modulators and does not require the same level of safety and dosing considerations.

[063] In certain embodiments where the treatment containers are housed within the pH modulation chamber (outer chamber), a compact system can be provided.

Definitions:

[064] It must be noted that, as used in this specification and the appended claims, the singular form "a", "an" and "the" include plural referents unless the context clearly dictates otherwise.

[065] As used herein, the term "about" in the context of a given value or range refers to a value or range that is within 20%, preferably within 10%, and more preferably within 5% of the given value or range.

[066] As used herein, the term "and/or" is to be taken as specific disclosure of each of the two specified features or components with or without the other. For example "A and/or B" is to be taken as specific disclosure of each of (i) A, (ii) B and (iii) A and B, just as if each is set out individually herein.

[067] As used herein, the term upstream/downstream refers to direction of wastewater flow.

[068] As used herein, the "phosphorus content in wastewater" is meant phosphorus in any form, such as organic phosphorus, polyphosphate or orthophosphate. The different forms of phosphorus can be soluble or particulate. The reactive phosphorus is mainly the soluble orthophosphate. The sum of all phosphorus forms is referred to as the total phosphorus.

[069] As used herein, "wastewater" is meant any form of fluid including contaminants such as that from domestic, municipal or industrial wastewater. Therefore, it will be understood that the present wastewater treatment apparatus and methods can be applied to any waste from domestic (residential, commercial, institutional, municipal) ('domestic' meaning the origin and the composition is similar to that of the wastewater of a residence) or industrial wastewater treatment systems. It can be used as a conjoint to such wastewater systems. [070] Embodiments of the present disclosure each have at least one of the above-mentioned object and/or aspects, but do not necessarily have all of them. It should be understood that some aspects of the present disclosure that have resulted from attempting to attain the above- mentioned object may not satisfy this object and/or may satisfy other objects not specifically recited herein.

[071] Additional and/or alternative features, aspects, and advantages of implementations of the present disclosure will become apparent from the following description, the accompanying drawings, and the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[072] For a better understanding of the present disclosure, as well as other aspects and further features thereof, reference is made to the following description which is to be used in conjunction with the accompanying drawings, where:

[073] Figure 1 is a schematic view of an apparatus for wastewater treatment, the apparatus having a pH modulation chamber and a treatment container according to an embodiment of the present disclosure;

[074] Figure 2 is a schematic view of an apparatus for wastewater treatment, the apparatus having a pH modulation chamber and three treatment containers, according to another embodiment of the present disclosure; [075] Figure 3 a top plan view of an apparatus for wastewater treatment, the apparatus having a pH modulation chamber and five treatment containers, according to yet another embodiment of the present disclosure;

[076] Figure 4 is a top plan view of the apparatus of Figure 3 with a roof removed for clarity; [077] Figure 5 is a cross-section of the apparatus of Figure 3 along the line A- A; [078] Figure 6 is a cross-section of the apparatus of Figure 3 along the line B-B; [079] Figure 7 is a side view of the apparatus of Figure 3, showing only the pH modulation chamber, three treatment containers, and a transportation system, according to an embodiment of the present disclosure;

[080] Figure 8 is a perspective exploded view of one of the treatment containers of Figure 3 and a lifting assembly according to an embodiment of the present disclosure;

[081] Figure 9 is a side exploded view of the treatment container and lifting assembly of Figure 8;

[082] Figure 10 is a perspective exploded view of one of the treatment containers of Figure 3 and a lifting assembly according to another embodiment of the present disclosure; [083] Figure 11 is a side exploded view of the treatment container and lifting assembly of Figure 10;

[084] Figure 12 is a schematic view of an apparatus for wastewater treatment, the apparatus having an pH modulation chamber and three treatment containers, according to yet another embodiment of the present disclosure; [085] Figure 13 is a perspective view of an apparatus for wastewater treatment, according to another embodiment of the present disclosure, with a side wall and the roof removed for clarity;

[086] Figure 14 is a top plan view of the apparatus of Figure 13; and

[087] Figure 15 is a cross-section of the apparatus of Figure 13 through the line C-C shown in Figure 14. DETAILED DESCRIPTION

[088] The present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including", "comprising", or "having", "containing", "involving" and variations thereof herein, is meant to encompass the items listed thereafter as well as, optionally, additional items. In the following description, the same numerical references refer to similar elements.

[089] Referring initially to Figure 1, broadly, there is provided an apparatus 10 for treating wastewater and modulating a pH of the wastewater, and particularly for reducing a phosphorus content in the wastewater. The apparatus 10 comprises a pH modulation chamber 12 (also referred to herein as an outer chamber) which is arranged to house at least one treatment container 14 (also referred to herein as an inner chamber or a treatment chamber). In the embodiment of Figure 1, the treatment container 14 is housed in the outer chamber 12 and is configured to house iron and/or calcium oxide material for contacting the wastewater in use. I other embodiments, the treatment container 14 and the outer chamber 12 may be separate but fluidly connected together, and both may be housed in a housing. The treatment container 14 is fluidly connectable to a source of the wastewater through an inlet 13, and fluidly connectable to the outer chamber 12 through an outlet 15. The height at which the wastewater is discharged into the treatment container 14 to contact the the carbon dioxide is lower than the height of the outlet 15 at which treated wastewater leaves the treatment container 14. Wastewater flow through the iron and/or calcium oxide material in the treatment container 14 is generally in an upwardly direction towards the outlet 15. Contact with the iron and/or calcium oxide material can reduce a phosphorus content in the wastewater, but can also raise the pH of the wastewater. The outer chamber 12 contains carbon dioxide or carbon dioxide enriched air. In other embodiments, instead of carbon dioxide, any other pH modulator material can be used such as a carbon source.

[090] In use, an effluent of the treatment container 14, which is released into the outer chamber 12, contacts carbon dioxide, to modulate the pH of the effluent, and particularly to reduce the pH. The apparatus 10 can be installed in-ground or above ground and can be for residential, commercial, municipal or industrial use.

[091] The apparatus 10 of Figure 2 differs from that of Figure 1 in that a plurality of treatment containers 14 are provided, at least two of which are fluidly connected to one another in a series. In Figure 2, three treatment containers 14a, 14b, and 14c are provided. The outlet 15 of the first treatment container 14a is in fluid communication with the inlet 13 of the treatment container 14b. The outlet 15 of the treatment container 14b is in fluid communication with the inlet 13 of the treatment container 14c. The outlet 15 of the end treatment container 14c of the series is in fluid communication with the outer chamber 12 and the carbon dioxide contained therein. In this way, wastewater is treated consecutively by the iron and/or calcium oxide material of each of the treatment containers 14a, 14b, 14c before pH modulation in the outer chamber 12. In other embodiments (not shown), the treatment container 14 is separate to the outer chamber 12 and fluidly connected thereto. In yet other embodiments, the treatment containers 14 are housed within the outer chamber 12 but are not removeable therefrom.

[092] Referring now to Figures 3-7, in which the apparatus 10 differs from that of Figure 2 in that the apparatus 10 of Figure 3 comprises two rows 16 of five treatment containers 14 housed in the outer chamber 12 (best seen in Figure 4). The treatment containers 14 of each row 16 are fluidly connectable to each other in series such that wastewater to be treated flows through each treatment container 14 of that row 16, starting from a first treatment container 14a of the row 16 through to a last treatment container 14e of that row 16. The two rows 16 of treatment containers 14 are arranged to be operated in parallel. The last treatment container 14e of each row 16 is configured to release the treated wastewater into the outer chamber 12 where it will contact the carbon dioxide and to modulate the pH, e.g. by lowering the pH to neutral or close to neutral. Optionally, the effluent of both the last treatment containers 14e of both rows 16 can be collected together before contacting the outer chamber 12. [093] It will be appreciated that different numbers and configurations of treatment containers 14 are possible according to the output need and acceptable hydraulic retention times. For example, the apparatus 10 may have more or less than the two rows 16 shown, may have more or less than the five treatment containers 14 in each row 16, and may also have stackable treatment containers 14. The treatment containers 14 could also be installed in multiple tanks (for example, five treatment containers in two separate tanks). The treatment containers 14 can be of any suitable size or shape.

[094] The iron and/or calcium oxide material in the treatment containers 14 comprises steel slag from steel production having a high pH, such as more than about a pH of 10. Typically, the steel slag is from an electric arc furnace which has characteristics of high phosphorus removal capability and non-toxicity, although steel slag from other types of steel production can be used. The slag is stored in barrels before use, preferably under an inert atmosphere. In an alternative embodiment, instead of slag, calcium oxide particles at a high pH can be used. In other embodiments, any other suitable metal oxide or other material which can lower a phosphorus level in wastewater with which it is in contact can be used.

[095] In this embodiment, the steel slag used with the apparatus 10 is in particulate form. Smaller particles have a higher contact area/volume ratio which can mean higher reactivity (e.g. faster treatment), however smaller particle sizes can lead to clogging. The inventors have discovered that slag particles having a diameter of more than about 2mm and less than about 10mm can avoid or minimize clogging without compromising reactivity too much. Therefore, the slag particles may be filtered and particles of more than about 2mm in diameter used with the present apparatus. The inventors have also discovered that treating wastewater with a 'coarse' particle size slag followed by 'fine' particle size slag can help to optimize the phosphorus removal whilst minimizing clogging. In this embodiment, coarse particles are defined as having an average diameter of about 5-10 mm, and fine particles are defined as those having an average particle size of about 2-3 mm.

[096] Therefore, in this embodiment treatment containers 14 having coarse particle sizes (about 5-10 mm diameter) are positioned upstream of treatment containers 14 having fine particle sizes (about 2-3 mm diameter). The proportion of coarse to fine slag particles can be varied according to the quality of the wastewater to be treated. The more suspended solids in the wastewater, the higher the proportion of coarse slag to fine slag that should be used. In the embodiment illustrated in Figures 3-7, the first two treatment containers 14, 14b contain coarse slag particles (average particle size of about 5-10 mm diameter) and the last three treatment containers 14c, 14d, 14e contain fine slag particles (average particle size of about 2-3 mm diameter). The treatment containers 14 may optionally also include larger inert or less reactive particles to minimize clogging of the slag with organic matter. The larger inert/less reactive particles may have an average particle size of about 10-20 mm diameter. They may comprise steel slag particles, gravel or any other inert particulate matter. [097] In another embodiment, slag particles of different sizes can be placed within the same treatment container 14. As the flow of wastewater in a treatment container 14 is generally upwardly, particles of different sizes can be layered horizontally in the treatment container 14. For example, a set of layers (going from upstream to downstream) can comprise a layer of coarse inert/less reactive particles (of about 10-20 mm diameter) (optional), a layer of coarse slag particles (of about 5-10 mm diameter), and then a layer of fine slag particles (of about 2-3 mm diameter). The set of layers, could be repeated within each treatment container 14, to provide an option of by-passing clogged layers by moving or positioning the wastewater inlet 13 to an unclogged portion of the set of layers. [098] The outer chamber 12 comprises side walls 18, a base 20 and a roof 22. At least one opening 24 for removal of the treatment containers 14 from the outer compartment 12 is defined in the roof 22. As best seen in Figure 3, two openings 24 are provided, one above each row 16 of treatment containers 14. In this embodiment, the opening 24 in one row 16 is positioned above the treatment container 14d, and the other opening 24 of the other row 16 is positioned over the treatment container 14b. This configuration minimizes structural reinforcement of the roof 22. Alternatively, the openings could be positioned differently, such as over the treatment container 14a of one row 16 and over the treatment container 14e of the other row 16. This alternative configuration may require reinforcement of the roof 22. In these configurations, the openings 24 are off-set with respect to a centre of the roof 22. [099] Each opening 24 is sized and shaped to allow removal of a single upright treatment container 14. A cover 26 is provided for each opening 24 which has been removed in Figure 3 for clarity. The method of removal of the treatment containers 14 through the opening 24 will be described later with reference to Figures 7-11. Access openings 28 are also defined in the roof 22. [100] The outer chamber 12 also comprises an outlet 30 for removal of the treated wastewater from the outer chamber 12. The wastewater which has been treated to remove its phosphorus and neutralize its pH, and which meets environmental regulation standards, can be released directly into the environment via the outlet 30. [101] The carbon dioxide, or other pH modulator, can be provided from any source. In this respect, the outer chamber 12 also comprises an inlet 31 (Figures 3 and 4) extending through one of the side walls 18 for supplying the carbon dioxide gas to the outer chamber 12. The inlet 31 is fluidly connectable to a diffuser 32 at the base 20 of the outer chamber 12, through a feed pipe 34. In use, carbon dioxide supplied through the inlet 31 is released through the diffuser 32 (Figure 4) to flow through the treated wastewater contained in the outer chamber 12.

[102] In another embodiment, instead of the carbon dioxide being released through a diffuser 32 at the base 20 of the outer chamber 12 to bubble through the wastewater as it rises, the carbon dioxide is supplied to the air layer above the wastewater level in the outer chamber 12. To enhance the carbon dioxide solubilisation at the surface of the wastewater surface, the outer chamber 12 includes a recirculation pump (not shown) within the volume of the wastewater. In other embodiments, the outer chamber 12 includes a "fountain type pump" (not shown) to produce turbulence on the wastewater surface for enhancing the carbon dioxide transfer.

[103] In the embodiment of Figures 3-7, the source of the carbon dioxide in the outer chamber 12 is an aerobic bioreactor (not shown) which produces carbon dioxide as a by-product. An example of such a bioreactor is described in US 7,582,211 filed March 7, 2007, the contents of which are herein incorporated by reference. Briefly, the bioreactor of US 7,582,211 comprises a reactor for treating wastewater, which can be connected to a septic tank, and including a ribbonlike device for promoting bacteria growth. In this particular embodiment, the apparatus 10 is fluidly connected to the bioreactor and the carbon dioxide in the form of carbon dioxide enriched air, which is a by-product of the conversion of the carbonaceous matter, is introduced into the outer chamber 12 through the outer chamber inlet 31. Forced air, interconnected vents, pumps, or the like may be included in the flow path. This can provide a substantially continuous carbon source supply, which can avoid or minimize downtime of the apparatus 10 or a reduction in wastewater treatment efficiency.

[104] In certain embodiments, the concentration of the carbon dioxide is 2,000 to 6,000 ppm and has a flow rate of 5 m³/hr. Alternatively, atmospheric carbon dioxide could be used with a higher flow rate. [105] In alternative embodiments, other sources of carbon are used to produce carbon dioxide as a pH modulator, such as wood chips housed in the outer chamber 12. In this case, the wood chips may need replacement or replenishment at certain intervals. In other embodiments, other pH modulators are used, such as acids to neutralize the alkaline effluent. [106] A wastewater inlet 36 is provided through the side wall 18 of the outer chamber 12 (Figures 3, 4 and 5). The wastewater inlet 36 is in fluid communication with a manifold 40. As best seen in Figure 4, the manifold 40 branches into two, and each branch of the manifold supplies wastewater to the first treatment container 14a of each row 16 of the treatment containers 14. This is one example configuration of the wastewater distribution and alternatives will be apparent to those skilled in the art and also described further below with reference to Figures 12-15.

[107] The source of the wastewater to be supplied through the wastewater inlet 36 can be any suitable source. In one embodiment, the wastewater is sourced from a bioreactor (not shown) such as the one described in US 7,582,211 filed March 7, 2007, the contents of which are herein incorporated by reference. The bioreactor may be the same bioreactor, described above, from which the carbon dioxide is sourced. In this respect, an outlet of the bioreactor (not shown) is fluidly connected to the wastewater inlet 36. The wastewater, which is an effluent from the bioreactor, may meet all wastewater requirements other than phosphorus levels, before treatment by the apparatus 10. The wastewater from the bioreactor is supplied directly to the wastewater inlet 36 of the apparatus 10 via a pump, gravitational flow, or any other suitable manner. In some embodiments, a reservoir (not shown) for storing the wastewater is provided downstream of the bioreactor and upstream of the apparatus 10. The reservoir is fluidly connected to the bioreactor to receive the wastewater from the bioreactor, and fluidly connected to the apparatus 10 to supply the stored wastewater to the wastewater inlet 36 of the apparatus 10. The reservoir can be positioned at a greater height than the wastewater inlet 36 of the apparatus 10.

[108] Turning now to the treatment containers 14, each treatment container 14 is barrel-like and is configured to house a body of slag particles which at any one time may comprise unreacted slag particles as well as hydroxyapatite particles and calcium carbonate (some of which may leach out). As the slag reacts, it expands slightly and may increase in weight, in some cases weighing up to about half a tonne (metric). Therefore, the treatment containers 14 are made of a material suitable for supporting the unreacted and reacted slag especially during the removal and installation of the treatment containers 14 into and out of the outer chamber 12. In this embodiment, the treatment containers comprise high density polyethylene (HDPE) or stainless steel, but can be made of any suitable material.

[109] Each treatment container 14 is arranged to restrict contact between the carbon dioxide in the outer chamber 12 and the iron and/or calcium oxide material in the treatment container 14, as well as between the atmospheric carbon dioxide and the iron and/or calcium oxide material. In this respect, it can be said that the treatment container 14 is selectively fluidly sealable. Contact between carbon dioxide and the steel slag particles can reduce the phosphorus reduction capability of the steel slag as a result of reactions with the carbon dioxide. In this respect, each treatment container 14 has a necked opening 42 on a top surface 44 which is sealable with a lid 46. The lid 46 may or may not be sealable. As best seen in Figures 8 and 9, the treatment container 14 has an inlet 48 in the form of an opening defined in the lid 46 for receiving an inlet pipe 50 of the inlet 13 through which wastewater can be supplied. The inlet pipe 50 extends towards the bottom of the treatment container 14. A washer 52 is provided around the necked opening 42, and a collar 54 is receivable over the lid 46. In other embodiments, the configuration of the treatment container 14 differs from that shown in Figures 8-11. For example, in one embodiment, instead of a removeable lid, the treatment container 14 has a non-removeable (fixed) lid. The fixed lid may be welded onto the necked opening 42, and be made of a suitable material such as high density polyethylene (HDPE).

[110] As seen in Figure 6, the inlet pipe 50 extends through the treatment container inlet 48 and is fluidly communicable with a flow distributor 56 positioned at or near a bottom 58 of the treatment container 14. The flow distributor 56 has two discharge ends from which the wastewater is discharged into the treatment container 14 in use. In other embodiments, the flow distributor 56 has four discharge ends. One or more of the discharge ends include a cap to avoid solid accumulation and blockage whilst allowing wastewater flow. Wastewater is provided through the inlet pipe 50 and is expelled through the flow distributor 56 into the slag contained in the treatment container 14. In use, as the flow distributor 56 expels the wastewater to be treated at or near the bottom of the treatment container 14, the wastewater flows generally upwardly through the body of slag particles in the treatment container 14.

[I l l] Each treatment container 14 is provided with a ventilation pipe 60 extending from its respective treatment chamber lid 46 to discharge gas into the environment. The individual ventilation pipes 60 of the treatment containers 14 in each row 16 fluidly connect to a common ventilation line 61 having a ventilation outlet 61 A through a vent 62 at the outer chamber roof 12. Each row 16 of treatment containers 14 has its respective common ventilation line. The vent 62 extends through the cover 26 of the opening 24. A valve (not shown) is provided between the treatment container 14 and the vent 62 which permits fluid flow out of the treatment container 14 and restricts fluid flow into the treatment container 14. The vent allows fluid exchange sufficient to compensate for wastewater level fluctuations in the treatment container. In this embodiment, the valve is a p-trap which contains oil at the bend for restricting air flow into the treatment container 14 whilst also avoiding an airlock in the treatment container 14. In another embodiment, instead of a p trap, two different valves are provided: one valve provides pressure release from the treatment container 14, and other vent is a vacuum breaker which would allow fluid flow into the treatment container 14 when the wastewater level decreases.

[112] In some situations, this configuration of the individual ventilation pipes 60 of each row 16 fluidly connected to a common ventilation line 61 allows wastewater to flow through the ventilation line 61 to by-pass a treatment container 14 within the row 16. This may be desirable if and when one of the treatment containers 14 becomes clogged which can result in headloss and reduced fluid flow. A "clogged" treatment container 14 means a treatment container 14 in which the wastewater flow resistance has increased to beyond an acceptable level. The acceptable level will depend on the exact configuration of the apparatus 10, for example whether the wastewater is being fed by gravity or by a pump. In certain embodiments, an acceptable level is up to or approaching the burst pressure of the treatment container. This may arise, for example, from organic matter fouling of the slag in the treatment container 14 or other types of blockages. Monitoring the pressure in each treatment container 14 can provide an indication of when the pressure is reaching undesirably high levels and when a by-pass treatment should be initiated. [113] In other situations, it may be desirable to avoid by-passing of a treatment container 14 altogether. In this respect, in certain embodiments, the height of the vent 62 and the ventilation outlet 61A can be raised relative to the wastewater inlet 36 to avoid wastewater by-pass through the common ventilation line 61. In the case of the wastewater being provided from a reservoir (not shown), the vent 62 and the ventilation outlet 61 A would be positioned higher than the height of the wastewater reservoir. In certain implementations, this can help to avoid by-passing a "clogged" treatment container 14.

[114] In a yet further embodiment (not shown), there is no common ventilation line 61 having a ventilation outlet 61A. In this embodiment, the individual ventilation pipes 60 of each treatment container 14 are directly fluidly connected to the vent 62, or any other vent in fluid communication with the environment to discharge gas from the treatment container 14.

[115] Turning now to the outlet 15 of the treatment containers through which the wastewater will flow from the treatment container 14 into either the next treatment container of the series, or to the outer chamber 12. At the last treatment container 14e of the row 16, the outlet 15 is in fluid communication with the outer chamber 12 to supply the treated wastewater to the outer chamber 12. For the last treatment container 14e, the outlet 15 is positioned near or at the top of that treatment container 14e. For the other treatment containers 14a, 14b, 14c and 14d, the outlet 15 is through the lid 46 of the treatment container 14 and is in fluid communication with the next treatment container 14 in the row 16. In use, the wastewater will flow into the outer chamber 12 and submerge the treatment containers 14. At the outlet 15 of both of the last treatment containers 14e of each row 16, an outlet pipe 66 extends from the outlet 15 and the outlet pipes 66 of each last treatment container 14e converge into a single wastewater delivery pipe 68.

[116] In use, wastewater enters the apparatus 10 through the wastewater inlet 36, flows into the manifold 40, and then into the first treatment container 14a through the treatment container inlet 48. The inlet pipe 50 carries the wastewater to the flow distributor 56 and out into the body of slag within the treatment container where it flows upwardly through the slag. A continuous flow will push the treated wastewater out of the first treatment container 14a through the treatment container outlet 15 and into the second treatment container 14b through the inlet 48. This process is repeated until the last treatment container 14e where the treated wastewater flows out of the outlet 15, through the outlet pipe 66 and the delivery pipe 68 and into the outer chamber where it fills the chamber up to the level of the outer chamber outlet 30. Meanwhile, carbon dioxide gas is supplied through the feed pipe 34 to the diffuser 32 where it is expelled into the treated wastewater. As it rises through the wastewater, it dissolves into the wastewater to reduce its pH. The treated wastewater leaves the outer chamber 12 through the outlet 30. Any build up of gases in the treatment containers escape through the ventilation pipes 60 and the vent 62. Any build up of carbon dioxide in the outer chamber 12 escapes through the outlet 30.

[117] When the apparatus 10 is installed underground, it will be appreciated that wastewater filling the outer compartment 12 can provide an opposing force to any inward force from the soil.

[118] Eventually, through the process of phosphorus removal and other ongoing mechanisms, the slag becomes less reactive. The slag is considered to be 'spent' and must be replaced by more reactive or fresher slag. Replacement of one or more of the treatment containers 14 which have become clogged may also be needed. In this respect, in certain embodiments, the first treatment container 14 in a row 16 can be treated as a filter for organic matter, and changed more frequently to avoid clogging of the other treatment containers 14 in that row 16. The efficacy of the slag can be monitored through (i) the pH in the last treatment container 14e, (ii) the calcium concentration in the last treatment container 14e or final effluent, or (iii) the phosphorus concentration in the last treatment container 14e or final effluent. [119] In order to facilitate replacement of the 'spent' slag in the treatment containers 14, a transportation system 80 is provided (Figures 8 and 9) which comprises a wheeled platform 82 for supporting the treatment container 14, the wheeled platform 82 being moveable along an inner surface of the outer chamber 12. The wheeled platform 82 comprises a support 81 with wheels 83. The wheeled platform 82 includes a front connector 84 and an oppositely facing back connector 86. The front and back connectors 84, 86 of this embodiment are inter-engageable male-female type connectors but other types of connectors are also possible. As best seen in Figures 5 and 6, the front connector 84 of one wheeled platform 82 can inter-engage with the back connector 86 of another wheeled platform 82. Each treatment container 14 rests on a dedicated wheeled platform 82. Each wheeled platform 82 is connected in series to adjacent treatment containers 14 in the same row 16 of treatment containers 14. Pulleys 88 are provided in an interior of the outer chamber 12 through which a cable 90 is threaded. The cable is a stainless steel wire, although any other cord-like material with sufficient mechanical properties can be used. The cable 90 has one end 92 attached to the wheeled platform 82 of the treatment container 14, and can be pulled by its free end 94 extending through the access opening 28 in the outer chamber roof 22 (Figure 7). The cable free end 94 can be pulled through the pulleys 88 to position the treatment containers 14 under the opening 24 for removal from the outer chamber 12. Tracks 96 are provided on a floor of the outer compartment 12 for guiding the movement of the wheeled platforms 82 but are not mandatory. For the double row configuration of this embodiment, a pair of tracks 96 parallel to one another is provided.

[120] Referring again to Figures 7 and 8, a lifting assembly 100 is provided for lifting and lowering the treatment containers 14. The lifting assembly 100 comprises a support structure 102 and connectors 104. The connectors 104 are attached to the wheeled platform 82 at one end 106. The connectors 104 have loops 108 at the other end for engaging with the support structure 102. The support structure 102 has hooks 110 extending therefrom for engagement with the loops 108 at the end of the connectors 104. Lifting equipment (not shown) can engage with the support structure 102, which is lowered down by the lifting equipment, to lift the lifting assembly 100 with the treatment container 14 and wheeled platform 82, substantially vertically out of the opening 24. [121] In use, to remove a treatment container 14 from the outer chamber 12, the cover 26 is removed to access the opening 24. The lifting assembly 100 is lowered and the loops 108 of the connectors 104 are engaged with the hooks 1 10 of the support structure 102. The support structure 102 is lifted vertically thereby also lifting the treatment container 14 and its associated wheeled platform 82 out of the outer compartment 12 through the opening 24. Back in the outer compartment 12, the wheeled platform 82 and its associated treatment container 14 are moved along the track 96 using the cables 90 to the unoccupied position left by the removed treatment container 14 under the opening 24. This treatment container 14 can then be lifted out of the outer compartment 12 in the same manner as the previous treatment container. This process is repeated until all of the treatment containers 14 in one row 16 have been removed. Replacement treatment containers 14 having fresh slag can then be lowered through the opening 24 into the outer compartment 12. The same process is repeated on the treatment containers 14 of the other row 16 of treatment containers 14 using the other opening 24.

[122] Treatment containers 14 can therefore be removed one-by-one without removing the entire apparatus 10, and therefore without requiring heavy lifting equipment. The treatment containers 14 can be accessed from the outside of the outer chamber 12. The installation and replacement can be performed without a confined space entry.

[123] Another embodiment of the lifting assembly 100 is shown in Figures 10 and 11. This embodiment differs from the embodiment of Figures 8 and 9 in that instead of the connectors 104 being attached to the wheeled platform 82, the connector 104 is a rod which extends into the treatment container 14 through the inlet pipe 50. At the base of the treatment container 14, the connector 104 is attached to a plate 112 which sits beneath the flow distributor 56 in use. The rod is a stainless steel wire although it will be appreciated than any other elongate structure can be used to connect lifting equipment with the plate 112. In use, once the steel slag is 'spent' it will generally have hardened, allowing the lifting of the treatment container 14 by engagement of a hook 114, attached to lifting equipment, to the connector 104. In this embodiment, the wheeled platform 82 is attached to the treatment container 14 and is also lifted out with the treatment container 14. The plate 112 can be made of any suitable material which can support the load of the slag and treatment container during lifting, such as high density polyethylene, stainless steel, etc. The plate has a smaller diameter than the treatment container opening 42 to facilitate its installment in the treatment container 14. In an alternative embodiment to that shown in Figures 2-9, the treatment containers 14 include subdivision(s) using baffles, to create a plug-flow. The wastewater is made to flow through coarse slag particles before fine slag particles which are contained in different subdivisions.

[124] In another alternative embodiment to that shown in Figures 2-9, instead of a plurality of discrete treatment containers, there are provided a plurality of side-by-side treatment columns (not shown) in the outer compartment. Each treatment column has a removeable liner for housing the slag which can be lifted out.

[125] In yet another alternative embodiment to that shown in Figures 2-9, at least one tank with baffles (not shown) creating a plug flow is provided as the treatment container. Coarse slag is positioned upstream and finer slag positioned downstream, thereby causing the wastewater to contact the coarser slag before the finer slag.

[126] A method is also provided for treating wastewater comprising: providing wastewater to be treated to the plurality of treatment containers 14 fluidly connected in series, allowing the wastewater to flow in sequence from the first treatment container 14a of the plurality of the treatment containers 14 to a last treatment container 14e of the plurality of the treatment containers, the outlet of the last treatment container being fluidly communicable with the outer chamber in which the plurality of treatment containers are housed; at each treatment container of the plurality of treatment containers, allowing contact of the wastewater with iron oxide and/or calcium oxide material contained therein to treat the wastewater to lower a phosphorus content in the wastewater; allowing the effluent to flow out of the last treatment container and into an outer chamber in which the treatment container is housed for contact with a source of carbon dioxide in the outer chamber to modulate the pH of the effluent; allowing the pH modulated treated wastewater to flow out of the outer chamber. The wastewater is allowed to contact coarse iron oxide and/or calcium oxide particles before contacting fine iron oxide and/or calcium oxide particles.

[127] Wastewater is supplied to the plurality of treatment containers at a rate that allows a hydraulic retention time in the treatment containers 14 of about 16 hours to about 24 hours. Carbon dioxide is supplied to the outer chamber at a rate which is determined based on the carbon dioxide concentration. For a carbon dioxide concentration of 400 ppm, a flowrate of about 200 to 400 times the wastewater flowrate is supplied to the outer chamber. For a carbon dioxide concentration of about 2000 ppm to about 6000 ppm, a flowrate of about 100 times the wastewater flowrate is supplied to the outer chamber.

[128] Referring now to Figures 12-15 in which another embodiment of the present disclosure is illustrated. The apparatus 10 of Figures 12-15 differs from that of Figures 2-7 in that a plurality of treatment containers 14 are provided in an outer chamber (pH modulation chamber) 12 which are arranged for parallel treatment instead of treatment in series. Wastewater does not flow from one treatment container 14 to another treatment container 14. Wastewater flows into each treatment container 14 through the inlet pipe 50 as before. However, the outlet 15 of the treatment container 14 does not fluidly connect to the inlet 50 of another treatment container 14. Instead, the outlet 15 of each treatment container is fluidly connected to the outer chamber 12 via a common outlet pipe 200 (best seen in Figure 13). Wastewater is thereby directed to flow into each treatment container 14, through the slag in the treatment container 14 in a generally upwardly direction, and out through the outlet 15, to the common outlet pipe 200 and into the outer chamber 12. This embodiment can help to reduce or minimize clogging and headloss in the treatment chambers 14.

[129] One or more of the treatment containers 14 have slag particle layers (not shown) such that larger slag particles (e.g. 5-10 mm diameter) are upstream of the smaller slag particles (e.g. 3-5 mm). Optionally, a layer of inert or less reactive particles can be included upstream of the larger slag particles.

[130] In other embodiments, a combination of "series" configuration (as shown in Figures 2- 11) and "parallel" configuration (as shown in Figures 12-15) is possible.

[131] In certain embodiments, the method comprises reducing or avoiding clogging of the slag particles in one or more of the treatment containers 14 by (i) backwashing of the slag particles using water and/or air, and/or (ii) applying a vibration of to the slag particles such as by shaking the treatment container 14. In this respect, in certain embodiments, the apparatus comprises a pump (e.g. a vacuum pump) fluidly connectable to the treatment container inlet 13 to pump out the contents inside the treatment container 14. In certain other embodiments, the apparatus comprises a pump to pump fluid from the pH modulation chamber 12 into the outlet 15 of the treatment container 14 to create a reverse flow. In that case a connecting pipe is also provided to the inlet 13 of the treatment container 14 that would become the outlet 15 during the backwash and the other end of that pipe connectable to a septic tank or a transport container.

[132] It will be appreciated that instead of carbon dioxide as the pH modulator, any other pH modulator can be used such as any inorganic carbon, including C0₂, HC0₃ and H₂C0₃. It will also be appreciated that the pH modulation chamber 12 and the treatment container(s) 14 may be separate and housed in a housing (not shown). Although the figures show the treatment container 14 inlet at the top of the treatment container 14, the inlet can be at any portion of the treatment container 14 such as its side or base. Although the figures show the pH modulation chamber as housing the treatment container chambers, they may be separate and both housed in a housing.

[133] Certain embodiments of the disclosure are illustrated by the following non -limiting examples. [134] Example 1

[135] The efficacy of phosphorus removal using different stainless steel slag particle sizes was investigated. Three categories of slag particles were used: Coarse slag (5- 10mm average diameter), fine slag (2-3mm average diameter), and medium slag (3-5mm average diameter).

[136] Wastewater was passed through three different columns operated in parallel and filled with different slag particle size ranges (about 2-3 mm, about 3-5 mm and about 5-10 mm). The columns had a diameter of about 6 inches and were filled up to a height of about 30 inches with stainless steel slag. The inlet was located at the base of the column and the outlet at the top of the column in an up-flow configuration. The columns were fed by peristaltic pumps with a secondary effluent. The columns' hydraulic retention time was 16 hours. The parameters of pH, orthophosphate, total phosphorus and calcium content were measured at the influent and the effluent for a period of 200 days.

[137] It was found that the smaller particle size range had higher pH, higher calcium concentration and better phosphorus removal. The influent average pH was 7.6, the 2-3 mm and the 3-5 mm effluent average pH was 11.0 and the 5-10 mm effluent average pH was 10.4. The influent average total phosphorus concentration was 5.1 mg P/L, the 2-3 mm effluent average was 0.5 mg P/L, the 3-5 mm effluent average was 0.6 mg P/L and the 5-10 mm effluent average was 0.9 mg P/L. The influent average orthophosphate concentration was 4.6 mg P-PO₄/L, the 2-3 mm effluent average was 0.2 mg P-PO₄/L, the 3-5 mm effluent average was 0.3 mg P-PO₄/L and the 5-10 mm effluent average was 0.4 mg P-PO₄/L. The influent average calcium concentration was 15.2 mg Ca/L, the 2-3 mm effluent average was 81.3 mg Ca/L, the 3-5 mm effluent average was 76.7 mg Ca/L and the 5-10 mm effluent average was 53.0 mg Ca/L The finer particles were also found to be effective for a longer time. After 200 days, the total phosphorus effluent concentrations of the 2-3 mm and the 3 -5mm columns was below 1 mg P/L while the total phosphorus effluent concentration of the 5-10 mm column reached a value of 1 mg P/L after 114 days.

[138] Example 2

[139] The efficacy of phosphorus removal using a pilot unit treating 1,260 L/d was investigated. A septic tank having a hydraulic retention time of 2.3 days received a raw domestic influent. The septic tank was connected to a Bionest™ bioreactor (including a ribbon-like device for bacteria growth as described in US 7,582,211) connected to a pumping station connected to a tank for reducing phosphorus content and adjusting pH. The tank had a hydraulic retention time of 2.3 days. The tank comprised first and second chambers, separated by a baffle, in fluid communication with one another. The first chamber had a volume which was about two-thirds of the total volume of the tank and was arranged to reduce the phosphorus content in the wastewater. The second chamber had a volume which was about a third of the total volume of the tank and was arranged to adjust the pH of the effluent from the first chamber. The first chamber housed bulk slag having a particle size of about 5-10 mm in diameter. Wastewater was supplied proximate the bottom of the first chamber through a low pressure distribution system. Pipes connecting the two chambers were installed in the baffle near the tank roof. The second chamber, was used as a pH adjusting unit. In this respect, an air pump located in the Bionest™ reactor was connected to a diffuser installed at the base of the second chamber. A carbon dioxide concentration of 2000 to 6000 ppm was pumped to the diffuser at a rate of about 5 m³/hr. The pipes located in the baffle were submerged in the wastewater, preventing or minimizing any gas exchange between the first and second chambers that could have reduced the phosphorus removal efficiency because of the carbon dioxide enriched air concentration. The parameters of pH, orthophosphate and total phosphorus were measured at the influent and the effluent for a period of 264 days. [140] The total phosphorus concentration at the influent of the tank was 3.1 mg P/L on average, the orthophosphate concentration was 3.1 mg P-PO₄/L and the pH was 7.1. The pH after the first chamber was 10.6 on average. The total phosphorus concentration at the effluent of the was 0.7 mg P/L on average, the orthophosphate concentration was 0.5 mg P-PO₄/L and the pH was 9.0. Additional tests showed that pH adjustment is possible with a smaller volume of the second chamber, such as about 10% of the second chamber volume used.

[141] Example 3

[142] The efficacy of phosphorus removal using an embodiment of the present apparatus and method (a pilot unit treating 1450 L/d) was investigated. A septic tank having a hydraulic retention time of 2.0 days received a raw domestic influent from a pumping station. The alimentation discharge was 500 L from 6 am to 9 am, 375 L from 11 am to 2 pm and 575 L from 5 pm to 8 pm.

[143] The septic tank was connected to a Bionest™ bioreactor having a hydraulic retention time of 2.0 days (including a ribbon-like device for bacteria growth as described in US 7,582,211). The bioreactor was connected to an embodiment of the present apparatus having a housing containing a pH modulation chamber and a plurality of treatment containers. The flow of wastewater from the bioreactor was provided to two rows of five treatment containers (barrels) fluidly connected in series (i.e. effluent from each barrel was caused to flow into the inlet of the next treatment container in the series). The two rows of five barrels were operated in parallel. The volume of each barrel was approximately 220 L. The two first barrels of each row were filled with larger particle size steel slag (about 5 to 10 mm) and the last three barrels were filled with smaller particle size steel slag (about 3 to 5 mm). The barrel inlet pipe was located at the top. Wastewater was discharged into the barrel proximate the base. Then with an up-flow configuration, wastewater flowed through the steel slag particles in the barrel. The outlet of the phosphorus treatment was located at or near the top of the barrel. Each barrel had a ventilation pipe allowing the air or other gases inside to escape.

[144] Treated water from the two rows of barrels was collected in the pH modulation chamber for pH modulation/neutralization. A diffuser was located at the base of the outer chamber. This diffuser was connected to an air pump located in the bioreactor and provided carbon dioxide at a rate of about 5 m /h. The carbon dioxide concentration was between 2000 and 6000 ppm. The parameters of pH, orthophosphate and total phosphorous were measured at the influent and the effluent of the apparatus for a period of 338 days. [145] The total phosphorous concentration at the influent of the apparatus was 5.13 mg P/L on average, the orthophosphate concentration was 5.05 mg P-P04/L and the pH was 7.72. Average fecal coliforms concentration was around 50 000 UFC/100 mL.

[146] The total phosphorous concentration at the effluent of the barrels was 0.4 mg P/L on average, the orthophosphate concentration was 0.31 mg P-P04/L and the pH was 10.69. Average fecal coliforms concentration was around 10 UFC/100 mL.

[147] The total phosphorous concentration at the pH modulation chamber effluent was 0.58 mg P/L on average, the orthophosphate concentration was 0.49 mg P-P04/L and the pH is 8.91. Average fecal coliforms concentration was around 10 UFC/100 mL. [148] Example 4

[149] The efficacy of phosphorus removal using an embodiment of the present apparatus and method (pilot unit treating 1440 L/d) was investigated. A septic tank having a hydraulic retention time of 1 day received a raw domestic influent from a pumping station. The alimentation discharge was 35 % from 6 am to 9 am, 25 % from 11 am to 2 pm, and 40 % from 5 pm to 8 pm. [150] The septic tank was connected to a pumping station which divided the alimentation discharge in two. Wastewater was distributed into two Bionest™ bioreactors (including a ribbonlike device for bacteria growth as described in US 7,582,211) in a parallel setting. One bioreactor had an ultraviolet (UV) lamp at the outlet, and the other bioreactor did not have a UV lamp. Each bioreactor was connected to a pumping station for supplying effluent from the bioreactor to the phosphorus reducing apparatus of the present disclosure. Inside the apparatus, the flow split in two rows of five treatment containers (barrels). The flow of wastewater from the bioreactor was provided to two rows of five treatment containers (barrels) fluidly connected in series (i.e. effluent from each barrel was caused to flow into the inlet of the next treatment container in the series). The volume of each barrel was approximately 220 L. The two first barrels of each row were filled with larger particle size steel slag (5 to 10 mm) and the last three barrels were filled with smaller particle size steel slag (3 to 5 mm). The barrel inlet pipe was located at or near the top of the barrel. Wastewater flowed through a pipe to the base of the barrel. Then with an up- flow configuration, wastewater flowed through the steel slag particles towards the outlet. The outlet of the treatment container was located at or near the top of the barrel. Each barrel had a ventilation pipe allowing the air and/or other gases inside the barrel to escape.

[151] Treated water from the two rows was collected in a pH modulation chamber (pH neutralization chamber) through a common outlet. The pH modulation chamber was between the ten barrels. This pH modulation chamber was arranged to adjust pH and had a diffuser located at the base of the tank. The diffuser was connected to an air pump located in the bioreactor and provided carbon dioxide to the pH modulation chamber at a rate of about 5 m /h. The carbon dioxide concentration was between 2000 and 6000 ppm. The parameters of pH, orthophosphate and total phosphorous were measured at the influent and the effluent for a period of 160 days.

[152] The total phosphorous concentration at the influent of the apparatus was 6.18 mg P/L, the orthophosphate concentration was from 5.6 mg P-P04/L. Fecal coliforms concentration for the reactor without UV lamp was around 41 707 UFC/100 mL. Fecal coliforms concentration for the reactor with UV lamp was 5 UFC/100 mL.

[153] The total phosphorous concentration at the effluent of the apparatus with UV lamp was 0.23 mg P/L on average, the orthophosphate concentration was 0.17 mg P-P04/L. Fecal coliforms concentration was 2 UFC/100 mL.

[154] The total phosphorous concentration at the effluent of the tank without the UV lamp was 0.37 mg P/L on average, the orthophosphate concentration was 0.34 mg P-P04/L. Fecal coliforms concentration was 4 UFC/100 mL. The average pH measured at the effluent was 7.82.

[155] Modifications and improvements to the above-described embodiments of the present disclosure may become apparent to those skilled in the art. The foregoing description is intended to be exemplary rather than limiting. The scope of the present disclosure is therefore intended to be limited solely by the scope of the appended claims.

Claims

CLAIMS What is claimed is:

1. An apparatus for treating wastewater, the apparatus comprising:

a treatment chamber for treating wastewater to reduce a phosphorus content in the wastewater; and a pH modulation chamber for treating an effluent of the treatment chamber to modulate the pH of the effluent;

the treatment chamber being configured to house iron and/or calcium oxide material for contacting the wastewater in use to treat the wastewater, and having an inlet for receiving the wastewater and an outlet for allowing the treated wastewater effluent to flow out of the treatment chamber and into the pH modulation chamber;

the pH modulation chamber being configured to treat the treated wastewater effluent from the treatment container with a carbon dioxide to modulate its pH, and having an outlet for the pH modulated effluent to flow out of the pH modulation chamber.

2. The apparatus of claim 1, wherein the treatment chamber comprises a treatment container which is selectively fluidly sealable to separate the iron and/or calcium oxide material from the carbon dioxide gas of the pH modulation chamber.

3. The apparatus of claim 2, wherein the pH modulation chamber is arranged to house the treatment container.

4. The apparatus of claim 2 or claim 3, wherein the treatment container is removeably housed in the pH modulation chamber, the pH modulation chamber comprises an opening defined in a wall of the pH modulation chamber, the opening being sized and shaped to allow removal of the treatment container therethrough.

5. The apparatus of any of claims 1-4, wherein the treatment chamber or the treatment container has a removeable liner for housing the iron and/or calcium oxide material.

6. The apparatus of any of claims 2-5, wherein the treatment chamber comprises a plurality of treatment containers, and the pH modulation chamber is arranged to house the plurality of treatment containers.

7. The apparatus of claim 6, wherein the plurality of treatment containers are fluidly connectable in series for wastewater to flow in sequence from a first treatment container of the plurality of treatment containers to a last treatment container of the plurality of treatment containers, the last treatment container having the outlet for allowing the treated wastewater effluent to flow out of the treatment container and into the pH modulation chamber.

8. The apparatus of claim 6 or claim 7, wherein the plurality of treatment containers are arranged as one or more rows of treatment containers in the pH modulation chamber.

9. The apparatus of any of claims 6-8, wherein at least one treatment container of the plurality of treatment containers contains calcium and/or iron oxide material having an average particle size which is larger than an average particle size of calcium and/or iron oxide material contained in another one of the plurality of treatment containers which is positioned downstream of the at least one treatment container of the plurality of treatment containers.

10. The apparatus of any of claims 2-9, wherein the treatment container or at least one of the plurality of treatment containers is individually moveable within the pH modulation chamber.

11. The apparatus of claim 10, further comprising a transportation system for moving the treatment container or the at least one of the plurality of treatment containers within the pH modulation chamber.

12. The apparatus of claim 11, wherein the transportation system comprises a wheeled platform for supporting the treatment container or the at least one of the plurality of the treatment containers, the wheeled platform being moveable along a floor of the pH modulation chamber.

13. The apparatus of claim 12, wherein the transportation system further comprises at least one pulley and a cable attachable at one end to the wheeled platform and threaded through the pulley to pull the wheeled platform using the other end of the cable.

14. The apparatus of claim 12 or claim 13, wherein the transportation system further comprises a track for guiding the movement of the wheeled platform.

15. The apparatus of any of claims 2-14, further comprising a lifting assembly, the lifting assembly comprising a support structure engageable with lifting equipment and having a connector engageable with the treatment container or at least one of the plurality of treatment containers.

16. The apparatus of claim 15, wherein the connector comprises an arm extendable into the treatment container or at least one of the plurality of treatment containers through an opening of the treatment container or at least one of the plurality of treatment containers and attachable to a plate.

17. The apparatus of claim 15, wherein the connector comprises arms extendable from the support structure and attachable to an outside of the treatment chamber or at least one of the plurality of treatment containers or the wheeled platform.

18. The apparatus of any of claims 1-17, further comprising an inlet for supplying carbon dioxide to the pH modulation chamber; and optionally wherein the inlet is fluidly connectable to a bioreactor which is arranged to treat carbonaceous matter in wastewater and to generate carbon dioxide as a by-product.

19. The apparatus of any of claims 1-18, further comprising a bioreactor fluidly connectable to the apparatus for supplying one or both of the wastewater and the carbon dioxide.

20. The apparatus of any of claims 1-19, wherein the calcium oxide and/or iron oxide material has an alkaline pH.

21. The apparatus of any of claims 1-20, wherein at least a portion of the calcium and/or iron oxide material in the treatment chamber or the treatment container comprises particles having an average particle size which is larger than at least another portion of the calcium and/or iron oxide material which is downstream so that as wastewater flows through the treatment chamber or the treatment container it contacts the average larger particle size portion before the smaller particle size portion.

22. The apparatus of any of claims 1-21, wherein the calcium oxide and/or iron oxide material comprises steel slag.

23. The apparatus of any of claims 1-22, wherein the calcium and/or iron oxide material comprises particles of more than about 2 mm diameter and less than about 20 mm in diameter, particles of more than about 2 mm diameter and less than about 10 mm in diameter, particles ranging from about 2 to about 10 mm in diameter, particles ranging from about 2 to about 4 mm in diameter, particles ranging from about 3 to about 5 mm in diameter and/or particles ranging from about 5 to about 10 mm in diameter.

24. The apparatus of any of claims 1-23, wherein the treatment chamber or the treatment container also houses inert particles, the inert particles optionally having a particle size of about 10-20 mm in diameter.

25. The apparatus of any of claims 2-24, wherein the treatment container or at least one of the plurality of treatment containers has an atmospheric vent for allowing gaseous flow out of the treatment container or the at least one of the plurality of treatment containers and for restricting gaseous flow into the treatment container or the at least one of the plurality of treatment containers, and optionally an outlet valve for preventing carbon dioxide gas flow from the pH modulation chamber into the treatment container or the at least one of the plurality of treatment containers.

26. The apparatus of any of claims 1-25, wherein the treatment chamber or the treatment container comprise a flow distributor proximate or downstream of the inlet for distributing the flow of wastewater in the treatment container.

27. The apparatus of any of claims 1-26, wherein the treatment chamber, treatment container or at least one of the plurality of treatment containers comprises at least two compartments in fluid communication with one another, each of the at least two compartments being configured to house the iron and/or calcium oxide material.

28. The apparatus of claim 27, further comprising at least one baffle for forming the two compartments.

29. An apparatus for treating wastewater, the apparatus comprising:

a housing having an inner chamber in fluid communication with an outer chamber;

the inner chamber being configured to house iron and/or calcium oxide material for treating wastewater to reduce a phosphorus content in the wastewater; and the outer chamber being configured to house a pH modulator for modulating the pH of the inner chamber effluent.

30. The apparatus of claim 29, wherein the pH modulator is an acid or is carbon dioxide.

31. The apparatus of claim 30, wherein the pH modulator is carbon dioxide and the outer chamber has a carbon dioxide inlet fluidly connectable to a bioreactor comprising a source of carbonaceous matter to provide the source of carbon dioxide.

32. The apparatus of any of claims 29-31, wherein the inner chamber comprises a treatment container which is selectively fluidly sealable to separate the iron and/or calcium oxide material from the pH modulator of the outer chamber, and the outer chamber comprising a pH modulation chamber, optionally the pH modulation chamber having an opening defined in a wall of the pH modulation chamber, the opening being sized and shaped to allow removal of the treatment container or a removeable liner, containing the iron and/or calcium oxide material, therethrough.

33. The apparatus of claim 32, wherein the inner chamber comprises a plurality of treatment containers, at least one of the plurality of treatment containers being selectively fluidly sealable to separate the iron and/or calcium oxide material from the pH modulator of the pH modulation chamber, and optionally the plurality of treatment containers being fluidly connected in series.

34. The apparatus of claim 33, wherein the outer chamber comprises a pH modulation chamber and the pH modulation chamber has an opening defined in a wall of the pH modulation chamber, the opening being sized and shaped to allow removal of at least one of the plurality of treatment containers, and optionally at least one of the plurality of treatment containers being moveable in the pH modulation chamber with respect to the opening for removal of the plurality of treatment containers through the opening.

35. The apparatus of claim 33 or 34, wherein the plurality of treatment containers are arranged as one or more rows of treatment containers.

36. The apparatus of any of claims 29-35, wherein an average particle size of a first portion of the iron and/or calcium oxide particles is relatively larger than an average particle size of a second portion of the iron and/or calcium oxide particles, the second portion being downstream of the first portion.

37. The apparatus of any of claims 29-36, wherein the calcium oxide and/or iron oxide material comprises steel slag.

38. The apparatus of any of claims 29-37, wherein the calcium and/or iron oxide material comprises particles of more than about 2 mm diameter and less than about 20 mm in diameter, particles of more than about 2 mm diameter and less than about 10 mm in diameter, particles ranging from about 2 to about 10 mm in diameter, particles ranging from about 2 to about 4 mm in diameter, particles ranging from about 3 to about 5 mm in diameter and/or particles ranging from about 5 to about 10 mm in diameter.

39. The apparatus of any of claims 29-38, wherein the inner chamber also houses one or more of: inert particles and particles having an average particle size of about 10-20 mm in diameter.

40. An apparatus for treating wastewater, the apparatus comprising:

a treatment chamber for treating wastewater to reduce a phosphorus content in the wastewater, and a pH modulation chamber for treating an effluent of the treatment chamber to modulate the pH of the effluent, the treatment chamber and the pH modulation chamber being in fluid communication with one another to allow wastewater flow from the treatment chamber to the pH modulation chamber;

the treatment chamber being configured to house iron and/or calcium oxide particles for treating the wastewater to reduce a phosphorus content in the wastewater; and the pH modulation chamber being configured to allow contact of the effluent from the treatment container with a pH modulator in the pH modulation chamber for modulating the pH of the treatment chamber effluent, wherein an average particle size of a first portion of the iron and/or calcium oxide particles is relatively larger than an average particle size of a second portion of the iron and/or calcium oxide particles, the second portion being downstream of the first portion.

41. The apparatus of claim 40, wherein the pH modulator is carbon dioxide.

42. The apparatus of claim 41, wherein the pH modulation chamber has a carbon dioxide inlet fluidly connectable to a bioreactor which is arranged to treat carbonaceous matter and to generate carbon dioxide as a by-product.

43. The apparatus of any of claims 40-42, wherein the treatment chamber comprises a treatment container fluidly communicable in use with the pH modulation chamber only through a wastewater outlet of the treatment container.

44. The apparatus of claim 43, wherein the pH modulation chamber is arranged to house the treatment container.

45. The apparatus of any of claims 42-44, wherein the pH modulation chamber has an opening defined in a wall of the pH modulation chamber, the opening being sized and shaped to allow removal of the treatment container or a removeable liner containing the iron and/or calcium oxide material therethrough.

46. The apparatus of any of claims 40-42, wherein the treatment chamber comprises a plurality of treatment containers, the treatment containers being selectively fluidly sealable to separate the iron and/or calcium oxide material from the pH modulator of the pH modulation chamber, and the pH modulation chamber has an opening defined in a wall of the pH modulation chamber, the opening being sized and shaped to allow removal of at least one of the plurality of treatment containers, at least one of the plurality of treatment containers being moveable in the pH modulation chamber with respect to the opening for removal of the at least one of the plurality of treatment containers through the opening, and optionally the plurality of treatment containers being fluidly connected in series.

47. The apparatus of any of claims 43-46, wherein the treatment container is individually moveable within the pH modulation chamber.

48. The apparatus of any of claims 32-39 or 43-47, further comprising a transportation system for moving the treatment container or at least one of the plurality of treatment containers within the pH modulation chamber.

49. The apparatus of claim 48, wherein the transportation system comprises a wheeled platform for supporting the treatment container or at least one of the plurality of treatment containers, the wheeled platform being moveable along a floor of the pH modulation chamber.

50. The apparatus of claim 49, wherein the transportation system further comprises at least one pulley and a cable attachable at one end to the wheeled platform and threaded through the pulley to pull the wheeled platform using the other end of the cable.

51. The apparatus of claim 49 or claim 50, wherein the transportation system further comprises a track for guiding the movement of the wheeled platform.

52. The apparatus of any of claims 32-39 or 43-51, further comprising a lifting assembly, the lifting assembly comprising a support structure engageable with lifting equipment and having a connector engageable with the treatment container or at least one of the plurality of treatment containers.

53. The apparatus of claim 52, wherein the connector comprises an arm extendable into the treatment chamber or at least one of the plurality of treatment containers through an opening of the treatment chamber or at least one of the plurality of treatment containers and attachable to a plate.

54. The apparatus of claim 53, wherein the connector comprises arms extendable from the support structure and attachable to an outside of the treatment chamber, at least one of the plurality of treatment containers, or the wheeled platform.

55. The apparatus of any of claims 29-39 or 40-54, wherein the calcium oxide and/or iron oxide material comprises steel slag.

56. The apparatus of any of claims 40-55, wherein the calcium and/or iron oxide particles comprise particles of more than about 2 mm diameter and less than about 20 mm in diameter, particles of more than about 2 mm diameter and less than about 10 mm in diameter, particles ranging from about 2 to about 10 mm in diameter, particles ranging from about 2 to about 4 mm in diameter, particles ranging from about 3 to about 5 mm in diameter and/or particles ranging from about 5 to about 10 mm in diameter.

57. The apparatus of any of claims 29-39 or 40-56, wherein the treatment container or at least one of the plurality of treatment containers also houses inert particles, the inert particles optionally having a particle size of about 10-20 mm in diameter, or particles of calcium and/or iron oxide material having an average particle size of about 10-20 mm in diameter.

58. The apparatus of any of claims 32-39 or 43-57, wherein the treatment container or at least one of the plurality of treatment containers has an atmospheric vent for allowing gaseous flow out of the treatment container and for restricting gaseous flow into the treatment container, and optionally an outlet valve for preventing carbon dioxide gas flow from the pH modulation chamber into the treatment container or the at least one of the plurality of treatment containers.

59. The apparatus of any of claims 29-39 or 40-58, wherein the treatment chamber or the inner chamber comprises a flow distributor proximate the inlet, at the inlet or downstream of the inlet for distributing the flow of wastewater in the treatment chamber or the inner chamber.

60. The apparatus of any of claims 29-39 or 40-59, wherein the treatment chamber comprises at least two compartments in fluid communication with one another, each of the at least two compartments being configured to house the iron and/or calcium oxide material.

61. The apparatus of claim 60, further comprising at least one baffle for forming the two compartments.

62. A method for treating wastewater, the method comprising:

providing wastewater to be treated to a treatment chamber having iron oxide and/or calcium oxide material therein;

allowing contact of the wastewater with the iron oxide and/or calcium oxide material to treat the wastewater to lower a phosphorus content in the wastewater;

providing the effluent from the treatment chamber to a pH modulation chamber for contact with carbon dioxide to modulate the pH of the effluent;

allowing the pH modulated treated wastewater to flow out of the pH modulation chamber.

63. The method of claim 62, wherein the pH modulation chamber comprises an outer chamber and the treatment chamber comprises a treatment container which is selectively fluidly sealable to separate the iron oxide and/or calcium oxide material from the carbon dioxide of the pH modulation chamber.

64. A method for treating wastewater, the method comprising:

providing wastewater to be treated to an inner chamber of a wastewater apparatus, the inner chamber housing iron oxide and/or calcium oxide material therein;

providing the effluent from the inner chamber into an outer chamber, in which the treatment container is housed, for contact with a pH modulator in the outer chamber to modulate the pH of the inner chamber effluent, optionally the pH modulator being carbon dioxide;

allowing the pH modulated treated wastewater to flow out of the outer chamber.

65. A method for treating wastewater, the method comprising:

providing wastewater to be treated to a treatment chamber for reducing a phosphorus content in the wastewater, the treatment chamber housing iron and/or calcium oxide particles; allowing the effluent from the treatment chamber to flow into a pH modulation chamber, the pH modulation chamber having a pH modulator therein for modulating the pH of the treatment chamber effluent, optionally the pH modulator being carbon dioxide;

allowing the pH modulated treated wastewater to flow out of the pH modulation chamber, wherein an average particle size of a first portion of the iron and/or calcium oxide particles is relatively larger than an average particle size of a second portion of the iron and/or calcium oxide particles, the second portion being downstream of the first portion.

66. The method of any of claims 62, 64 or 65, wherein the calcium oxide and/or iron oxide material comprises steel slag.

67. The method of any of claims 62-66, wherein the iron oxide and/or calcium oxide material comprises particles ranging from about 2 to about 10 mm in diameter, particles ranging from about 2 to about 4 mm in diameter, particles ranging from about 3 to about 5 mm in diameter and/or particles ranging from about 5 to about 10 mm in diameter.

68. The method of claim 67, wherein the treatment container, inner chamber or treatment chamber also houses inert particles, the inert particles optionally having a particle size of about 10-20 mm in diameter, or particles of calcium and/or iron oxide material having an average particle size of about 10-20 mm in diameter.

69. The method of any of claim 62-68, comprising allowing the wastewater to be treated to contact larger sized iron oxide and/or calcium oxide particles before contacting smaller sized iron oxide and/or calcium oxide particles.

70. The method of any of claims 64-69, wherein the pH modulator is carbon dioxide, the method further comprising supplying carbon dioxide from a bioreactor.

71. The method of any of claims 64-69, further comprising supplying the wastewater to be treated from a bioreactor.

72. The method of any of claims 62 -71, wherein the wastewater to be treated is supplied at or near a bottom of the treatment container, inner chamber or treatment chamber, and the wastewater is allowed to flow upwardly through the iron oxide and/or calcium oxide material towards an outlet of the treatment container, inner chamber or treatment chamber.

73. The method of any of claims 62-72, wherein the treatment chamber or the inner chamber comprise a treatment container which is selectively fluidly sealable to separate the iron oxide and/or the calcium oxide material from the pH modulator.

74. The method of claim 73, further comprising providing a plurality of treatment containers and supplying the wastewater to be treated into each treatment container of the plurality of treatment containers from a wastewater inlet of the apparatus, or from an outlet of one of the treatment containers of the plurality of treatment containers.

75. The method of claim 73 or claim 74, further comprising providing a plurality of treatment containers and ventilating each one of the plurality of treatment containers through a common ventilation pipe or through individual ventilation pipes.

76. The method of any of claims 62 to 73, further comprising moving a treatment container or treatment chamber proximate an opening in a roof of the outer compartment or the pH modulation chamber using a wheeled platform supporting the treatment container or treatment chamber to be removed.

77. The method of any of claims claim 73-76, further comprising engaging the treatment container and/or the wheeled platform with a lifting assembly; and lifting the treatment container and/or the wheeled platform out of the opening in the outer chamber.

78. The method of claim 76 or claim 77, further comprising guiding the wheeled platform using a track associated with the outer compartment.