Patent AU-2016390808-B2 (AU)
Title: Process and facility for the treatment of livestock waste
Inventor: LEVIN GAL
IPC: C02F11/00
Filed: 2016-11-01
Granted: 2019-07-18
Abstract: (12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (19) World Intellectual Property (1) OrganizationIIIIIIIIIIIDIIDIIIIIIIDIIIIIIIIIII International Bureau (10) International Publication Number (43) International Publication Date W O 2017/203505 A1 30 November 2017 (30.11.2017) W IPO I PCT (51) International Patent Classification: (74) Agent: GUTTMANN, Thomas et al.; Luzzatto & Luzzat C02F 9/00 (2006.01) C05F 17/00 (2006.01) to, P.O. Box 5352, 8415202 Beer Sheva (IL). C02F 11/04 (2006.01) A01C3/00 (2006.01) (81) Designated States (unless otherwise indicated, for every C02F 3/30 (2006.0 1) C02F 1/66 (2006.0 1) kind of national protection available): AE, AG, AL, AM, C5F3/00(2006.01) AO, AT, AU, AZ, BA, BB, BG, BH, BN, BR, BW, BY, BZ, (21) International Application Number: CA, CH, CL, CN, CO, CR, CU, CZ, DE, DJ, DK, DM, DO, PCT/IL2016/051177 DZ, EC, EE, EG, ES, Fl, GB, GD, GE, GH, GM, GT, HN, (22) International Filing Date: HR, HU, ID, IL, IN, IR, IS, JP, KE, KG, KN, KP, KR, KW, 01 November 2016 (01.11.2016) KZ, LA, LC, LK, LR, LS, LU, LY, MA, MD, ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI, NO, NZ, OM, PA, (25) Filing Language: English PE, PG, PH, PL, PT, QA, RO, RS, RU, RW, SA, SC, SD, (26) Publication Language: English SE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, TN, TR, TT, TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW. (30) Priority Data: (84) Designated States (unless otherwise indicated, for every 245872 26 May 2016 (26.05.2016) IL kind of regional protection available): ARIPO (BW, GH, (71) Applicant: S.G.T.-SUSTAINABLE GREEN TECH- GM, KE, LR, LS, MW, MZ, NA, RW, SD, SL, ST, SZ, TZ, NOLOGIES LTD [IL/IL]; 12 Ha'Melacha Street, Pob UG, ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, RU, TJ, 8641, 4250547 Netanya (IL). TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, Fl, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, LV, (72)Inventor: LEVIN,Gal;7ChitmanUziStreet,4266105Ne- MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK, SM, tanya(IL). TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, GW, KM, ML, MR, NE, SN, TD, TG). (54) Title: PROCESS AND FACILITY FOR THE TREATMENT OF LIVESTOCK WASTE Irr3 v9 5 Fig.2 (57) Abstract: The invention provides an efficient system for treating livestock waste, particularly waste from cattle or pig farming. The new facility and method employ special transfers of slurry streams through ASBR, SBR, and a unique pretreatment reactor, resulting in treated water, quality compost, and biogas. W O 2017/203505 A03505AlII|I||||||I|I|I||||I|I|||||I|||I|I|||||||||||||||||||||||| Declarations under Rule 4.17: - of inventorship (Rule 4.17(iv)) Published: - with international search report (Art. 21(3)) WO 2017/203505 PCT/IL2016/051177 PROCESS AND FACILITY FOR THE TREATMENT OF LIVESTOCK WASTE Field of the Invention 5 The present invention relates to the treatment of livestock waste. More particularly, the invention relates to system and process for converting livestock waste into compost, treated water, and energy. Background of the Invention 10 The treatment of wastes, particularly livestock waste, is a critical problem in the majority of developed countries, as it causes grave environmental and economic concerns. Large farms - 10,000 and more animals - exert pressure on the ecosystem and present problems difficult to solve both in the short term and the long term. In an attempt to prevent ecological disaster, various 15 countries have legislated limitations to the amount of livestock wastes which may spread per year per surface unit. For example, in Europe a spreading limitation has recently been introduced based on the nitrogen contents of wastes, virtually limiting the size of pig farms. 20 Traditionally, organic matter containing excessive biological oxygen demand (BOD) has been treated using microbial action. The process begins with the separation of the organic matter from the remainder or liquid fraction, forming a mass of solids in the form of an activated sludge. Treatment typically involves digestion of the organic material through fermentation of 25 the sludge involving aerobic or anaerobic bacterial action or some combination thereof. These processes are used to reduce the chemical oxygen demand (COD) and biological oxygen demand (BOD) of the material to an environmentally safe level. It is also necessary to remove undesirable inorganic materials from the water fraction, which typically contains WO 2017/203505 PCT/IL2016/051177 -2 undesirable quantities of phosphorus and nitrogen compounds including phosphates and nitrates. Conventional wastewater treatment systems may include pretreatment, 5 primary treatment, secondary treatment, and advanced treatment. Pretreatment includes screening, comminuting (mechanical cleaning of screens by shredding solids to a size which can pass through screen openings), degritting, and grease and scum removal. Primary treatment includes removal of suspended solids from wastewater by clarification and 10 skimming. This typically involves a tank or channel and the steps of reducing flow velocity, settling heavier solids, and skimming relatively light solids. Primary treatment may include anaerobic digestion processes, aerobic digestion processes, or a combination thereof. Primary treatment systems typically include sludge collection mechanisms, sludge suction devices, grit 15 removal devices, and sludge dewatering devices to reduce the volume of sludge to be disposed. Secondary treatment systems are typically aerobic systems including an aeration phase and a clarification phase. Such systems typically include an aeration tank, an air distribution system, a clarifier, sludge collection mechanisms, and sludge removing devices. Advanced 20 treatment includes further removal of suspended and dissolved organic solids by means including filtration and removal of pathogens by oxidation, chlorination or heating, precipitation of minerals, adsorption, or other methods. In additional steps of the advanced treatment, the purified liquor from the clarifier is typically filtered and refined through chlorination, 25 oxidation, or heating. In the activated sludge process of primary or secondary treatment, microorganisms are contained in an activated sludge and mixed with incoming wastewater, which provides food for the microorganisms whereby 30 more activated sludge is produced. Such mixing is accomplished in an aeration tank or channel. In the aerobic activated sludge process, oxygen is WO 2017/203505 PCT/IL2016/051177 - 3 intrinsically mixed with the activated sludge and the wastewater. The microorganisms use the solids as nutrients for their growth and reproduction, converting the suspended organic solids into biomass, carbon dioxide and water. The aerobic activated sludge process therefore typically 5 includes mixing wastewater, activated sludge, and oxygen in an aeration tank; consuming suspended organic solids by bacteria; settling activated sludge in a clarifier; returning the activated sludge to the aeration tank for further treatment; removing purified liquor from the clarifier; and removing and disposing of the final, inert sludge. Existing processes and installations for the treatment of such livestock wastes, especially for large farms, have generally been large scale operations having high installation costs. There exists a need to provide a compact, low cost system and method for treating wastewater. Summary of the Invention The invention provides a facility for treating a daily volume of livestock waste water, comprising a) a collecting basin for continually collecting and stirring raw livestock liquid wastes; b) a pretreatment channel having an 20 inlet end and an outlet end, capable to contain at least said daily volume of waste water, connected at said inlet end with said collecting basin and accepting said raw wastes, which flow through the channel and form a pretreated waste water while allowing for partial settling of dispersed solids and enriching the lower part of the channel with said solids relatively to the 25 upper part; c) an anaerobic reactor connected with said channel at said outlet end and accepting said pretreated waste water from the middle or upper part of said channel in separate batches, each batch allowed to react in the tank and partially settle, forming anaerobically treated waste water being enriched with solids in the lower part of the reactor relatively to the upper 30 part, wherein a portion of said anaerobically treated waste water from said lower part is fed to said channel at said inlet end where it combines with said WO 2017/203505 PCT/IL2016/051177 -4 raw wastes; d) an aerobic stirred reactor connected with said channel at said outlet end and accepting said pretreated waste water from the middle or upper part of said channel in separate batches, and further connected with said anaerobic reactor and accepting said anaerobically treated water from 5 the upper part of said anaerobic reactor in separate batches, each batch allowed to react in the tank and partially settle, forming aerobically treated waste water being enriched with solids in the lower part of the reactor relatively to the upper part, wherein a portion of said aerobically treated waste water from said lower part is fed back to said anaerobic reactor, and 10 said aerobically treated water from the upper part being removed as a safe water product; and e) a compost basin to which cellulose based solid waste is fed, connected with said pretreatment channel at said outlet end and accepting said pretreated waste water from the lower part of said channel, the basin provided with mixing means, whereby providing a quality compost; 15 wherein said daily volume of livestock waste water is converted to a quality compost and safe water for release into municipal system or for use in agriculture. In one embodiment of the invention, the facility comprises a) said basin which has a volume to contain at least two of said daily volumes of waste water; b) said pretreatment channel which has a length of at least 10 20 times greater than its width, and a volume to contain at least two of said daily volumes of waste water; c) said anaerobic reactor which has a volume to contain at least one said daily volume of waste water, preferably at least two said daily volumes, and is provided with collecting means to collect and process biogas to provide energy for running the facility; d) said aerobic 25 reactor which has a volume to contain at least one said daily volume of waste water, preferably at least two said daily volumes, and is provided with air dispersing means; and e) said compost basin which has a volume to contain at least two, preferably at least five, of said daily volumes, and is provided with mixing means which regularly mix said cellulose waste and said waste 30 water, and transport means which transport the cellulose waste into the basin and the ready compost out; wherein said daily volume of livestock WO 2017/203505 PCT/IL2016/051177 -5 waste water is converted to a quality compost and safe water for use in agriculture or for disposal. The system of the invention is very efficient but also economically less demanding; among others, the sediment channel, possibly a simple long rectangular parallelepiped dug in the ground and 5 made water-proof, even though it is technically a simplest possible element, without any expensive technical means of usual reactors, substantially contributes to the efficiency of the process. The facility according to the invention may be adjusted to any need in a 10 flexible way, typically being configured to treat from 50 to 400 M3 per day, but possibly up to 2000 M 3 per day or more. Said anaerobic reactor is advantageously anaerobic sequencing batch reactor (ASBR) and said aerobic reactor is advantageously sequencing batch reactor (SBR). The facility according to the invention further comprises transfer means for transferring 15 the treated liquid from said collector, via said channel and said anaerobic reactor, into said aerobic reactor and to said compost basin, the means comprising pumps, and possibly gravity driven means. In a preferred embodiment, the facility of the invention comprises automation means, comprising at least one microprocessor, and analytical measuring means, 20 liquid level sensors, analytical means for automatic sampling and measuring the concentration of components, including the amount of solids, in the treated water, and the means to analyze the liquid parameters, including the concentration of solids, along the height of said anaerobic and aerobic reactors. Said microprocessor(s) advantageously manage transferring the 25 materials in the system, and manage the steps of the process. The processed waste may originate in any animal farming. Advantageously, the system of the invention is employed in cattle farming or piggeries. In a preferred embodiment, the facility and the method of the invention are employed in pig farming. WO 2017/203505 PCT/IL2016/051177 -6 The invention provides a process of treating a livestock waste water, comprising i) collecting raw liquid waste in a stirred collecting tank; ii) transferring said raw liquid waste from said collecting tank to a non-stirred, flow-through channel reactor, said raw liquid waste providing a pretreated 5 liquid waste in said channel; iii) transferring said pretreated liquid waste from said channel via a first outlet to an ASBR and to a SBR at a transfer rate of v3, and via a second outlet to a compost basin at a transfer rate of v4, where said pretreated liquid waste is mixed in said basin with a cellulose waste regularly added to said basin, wherein said v4 is at most 20% of said 10 v3, for example about 10% of said v3, and wherein said second outlet is closer to the bottom of said basin than said first outlet, thereby obtaining compost; iv) transferring a part of said pretreated water from said first outlet to said SBR at a transfer rate of vI and a part to said ASBR at a transfer rate of (v3 - vII) wherein said vi is either zero or up to v3/3, usually zero or up to 15 v3/5, and reacting said pretreated waste water in said ASBR, allowing said waste water to settle, thereby obtaining an anaerobically treated waste water, the solids being more concentrated in the lower part of ASBR (sludge) than in the upper part of ASBR; v) optionally collecting biogas via a gas collector; vi) transferring said anaerobically treated waste water from said 20 upper part of ASBR via a third outlet to said SBR at a transfer rate of v5, and transferring said anaerobically treated waste water from said lower part of ASBR via a fourth outlet to said channel at a transfer rate of v6, wherein said v6is at most 15% of said v5, and wherein said fourth outlet is closer to the bottom of said ASBR than said third outlet, thereby supplying to said 25 channel an activated sludge; and vii) reacting said anaerobically treated waste water in said SBR, allowing said waste water to settle, thereby obtaining an aerobically treated waste water, the solids being more concentrated in the lower part of SBR (sludge) than in the upper part of SBR, and transferring said aerobically treated waste water from said upper part of 30 SBR via a fifth outlet at a transfer rate of v7 to obtain safe treated water, and transferring said aerobically treated waste water from said lower part of WO 2017/203505 PCT/IL2016/051177 -7 SBR via a sixth outlet back to said ASBR at a transfer rate of v8, wherein v8 is at most 5% of said v7, and wherein said sixth outlet is closer to the bottom of said SBR than said fifth outlet; thereby obtaining safe water for release into municipal system or for use in agriculture, and further a quality 5 compost, and optionally biogas. Said steps of transferring materials in the process of the invention usually comprise portions, which are processed sequentially, usually in 2 to 6 batches a day. Said step iv) comprises homogenization of the reactor content which is attained by inflow and outflow of the liquids. Said transferring the pretreated liquid waste from said 10 first outlet to the ASBR and SBR in steps iii) and iv) comprises branching the stream of said water, preferably via a regulated valve, so that only up to 1/3 of the stream is transferred to the SBR and only at certain periods; usually, the water is allowed to flow into the SBR when the pH in SBR has decreased under the value of 6.5, and the flow is stopped when the pH reaches a 15 predetermined value, for example at least 6.9, such as at least 7.4, so that said v11 is usually either zero or up to v3/3, such as up to v3/5. Said step vii) comprises homogenization of the reactor content which is attained by an intensive air influx and dispersion, and by an intensive mechanical stirring. The mixtures in said steps iv) and vii) are usually allowed to settle for a 20 period of time between about 1 to about 12 hours. The process of the invention is preferably employed for livestock waste water comprising pigs or cattle. In a preferred embodiment of the invention, provided is a process for treating 25 a piggery waste water, comprising passing said water through a system comprising - a pretreatment, flow-through, non-stirred, settling channel at least 10 times longer than wide, - an ASBR, and 30 - a SBR, WO 2017/203505 PCT/IL2016/051177 - 8 wherein aportion of sludge from said SBR is returned to said ASBR, a portion of sludge from said ASBR is returned to said channel, and a portion of sludge from said channel is mixed with a cellulose based waste to form compost; thereby providing a safe water and a high-quality compost. Brief Description of the Drawings The above and other characteristics and advantages of the invention will be more readily apparent through the following examples, and with reference to the appended drawings, wherein: 10 Fig. 1. is a schematic representation of one embodiment of the system according to the invention, which converts animal water waste and cellulose-based waste to safely treated water, high-quality compost, and biogas; Fig. 2. is a schematic representation of one embodiment of the system 15 according to the invention; equipment elements 1 to 6 and outlets 12 to 18 constitute the base of a facility according to the invention, materials 7 and 8 enter the process of the invention, and materials 9 to 11 are produced in the process, and transfer rates v1 to vii characterize the movement of the materials in the process of the 20 invention; and Fig. 3. is a schematic representation of one embodiment of the system according to the invention, which provides clean water from animal liquid waste, and which further provides compost and biogas as side products while utilizing cellulose waste; the system comprises 25 collecting basin 1 and compost basin 5, primary treatment elements 2 and 3 (channel reactor and ASBR), secondary treatment element 4 (SBR), tertiary treatment element 19 (sand filter), and quaternary treatment elements 20-24 (microfilter, carbon filter 1, carbon filter 2, RO device, carbon filter 3). WO 2017/203505 PCT/IL2016/051177 -9 Detailed Description It has now been found that piggery liquid waste can be cost-effectively and efficiently treated in two sequencing batch reactors connected in series, of which the first one is anaerobic sequencing batch reactor (ASBR) and the 5 second one is aerobic sequencing batch reactor (SBR), wherein a) collected raw liquid waste is first pretreated in a non-stirred channel reactor, providing a pretreated liquid waste to be fed to said ASBR, b) a small part of sludge from said ASBR is dosed to said channel, where it combines with said raw liquid waste; c) a small part of sludge from said SBR is dosed to said 10 ASBR, and d) a small part of said pretreated liquid waste is fed to a compost basin where it is mixed with a cellulose waste; thereby producing purified water from said SBR and compost from said basin. The term sludge in this context means that the liquid comprises more suspended materials that the average content in the reactor from which it flows, as a result of 15 sedimentation. The facility according to the invention comprises at least elements as schematically depicted in Fig. 1. Livestock waste water flows through collecting basin (1) and through settling flow-through channel reactor (2), 20 and further in parallel to ASBR (3) and SBR (4) to produce treated water, and to compost basin (5) to be mixed with cellulose-comprising waste and produce compost; in parallel, a relatively small amount of sludge flows from SBR to ASBR and from ASBR to the channel. Said channel enables preliminary anaerobic hydrolytic decomposition of waste. Said ASBR reactor 25 is advantageously provided with a gas collector (6) to produce biogas. Thus, in the facility according to the invention, and according to the method of the invention, livestock waste and cellulose waste are processed to produce treated water, compost, and biogas. 30 In a preferred embodiment, the facility and the process according to the invention comprise elements as the system schematically depicted in Figs. 1 WO 2017/203505 PCT/IL2016/051177 - 10 and 2 to which the following description relates. A preferred process of treating liquid piggery waste (7) comprises i) collecting raw liquid waste in a stirred collecting tank (1) at a rate v1 (all rates are in M3 per day), wherein v1 is usually between 20 and 200 m3 /d; ii) transferring said raw liquid waste 5 from said collecting tank to a non-stirred, flow-through channel reactor (2) at a second transfer rate v2, said raw liquid waste providing a pretreated liquid waste in said channel; iii) transferring said pretreated liquid waste from said channel via a first outlet (12) to an ASBR (3) at a third transfer rate v3, and via a second outlet (13) to a compost basin at a fourth transfer rate v4, where 10 said pretreated liquid waste is mixed in said basin with a cellulose waste (8) added at a ninth transfer rate v9, wherein said fourth transfer rate is at most 20% of said third transfer rate, and preferably at most 15% of said third transfer rate, for example about 10% of said third rate, and wherein said second outlet is closer to the bottom of said basin than said first outlet, 15 thereby obtaining compost (11) at a tenth rate v1; iv) reacting said pretreated waste water in said ASBR, allowing said waste water to settle, thereby obtaining an anaerobically treated waste water, the solids being more concentrated in the lower part of ASBR (sludge) than in the upper part of ASBR; v) optionally collecting biogas (9) via a gas collector (6); vi) 20 transferring said anaerobically treated waste water from said upper part of ASBR via a third outlet (14) to said SBR at a fifth transfer rate v5, and transferring said anaerobically treated waste water from said lower part of ASBR via a fourth outlet (15) to said channel at a sixth transfer rate v6, wherein said sixth transfer rate is at most 15% of said fifth transfer rate, for 25 example about 10% of said fifth rate, and wherein said fourth outlet is closer to the bottom of said ASBR than said third outlet, thereby supplying to said channel an activated sludge; vii) reacting said anaerobically treated waste water in said SBR, allowing said waste water to settle, thereby obtaining an aerobically treated waste water, the solids being more concentrated in the 30 lower part of SBR (sludge) than in the upper part of SBR, and transferring said aerobically treated waste water from said upper part of SBR via a fifth WO 2017/203505 PCT/IL2016/051177 - 11 outlet (16) at a seventh transfer rate () to obtain treated water (10), and transferring said aerobically treated waste water from said lower part of SBR via a sixth outlet back to said ASBR at an eighth transfer rate v8, wherein said eighth transfer rate is at most 5% of said seventh transfer rate, for 5 example about 2% of said seventh rate, and wherein said sixth outlet is closer to the bottom of said SBR than said fifth outlet. Said transfer rates usually comprise portions (batches) in which the liquid is transferred from one part of the system to the other. Particularly, said steps iv) to vi) usually comprise from 2 to 6 batches a day. As is usual in sequencing batch reactors, a part of 10 the maximal volume of said ASBR and SBR, such as from 1/10 to 1/2 is added in one batch, the content of the reactor is homogenized, the reaction is allowed to run. The homogenization in said ASBR is achieved at least by inflow and outflow of the liquid, optionally by a stirrer. The homogenization said SBR is achieved by an intensive air influx and dispersion, and by an 15 intensive mechanical stirring. In each batch, the mixture is allowed to settle for a period of between 3 and 12 hours in said ASBR, such as between 4 and 6 hours; each cycle usually takes between about a quarter to a half a of the day. In said SBR, the mixture is allowed to settle usually between 0.5 and 3 hours, such as 1-2 hours. Since the second, the fourth, and the sixth outlets 20 are closer to the bottom than the average liquid part in the system, fractionations occur in the involved stages. The raw liquid waste usually comprises 1-3 solids; the waste usually contains between 1.2% and 1.8% non aqueous materials, such as 1.5%, usually comprising from about 0.6 to 0.9% suspended particles. The liquid in said second, fourth, and sixth outlets may 25 contain up to 10% non-aqueous materials, typically between 4% and 8%, for example 6%. The first, the third, and the fifth outlets drain away decanted liquids, and their contents of non-aqueous materials may be, in some embodiments of the invention, for example less than about 0.8%, less than about 0.2%, and less than about 0.08% respectively. WO 2017/203505 PCT/IL2016/051177 - 12 In one aspect, the invention provides a semicontinual effective process for cleaning livestock waste water, at any scale, during which sewage is continually collected, and processed in repeated batches to purified water, compost, and biogas. When relating to Fig. 2, waste materials (7) and (8) 5 provide products (9), (10), and (11). Regarding material flows and transfer rates, v1 to v8 comprise aqueous liquids, usually aqueous suspensions, whereas v9 and v10 comprise wet solids; practically, also v9 and v10 may be conveniently expressed in m3/d. Practically, in the semicontinual process of the invention, vl+v9= v7+v10, since the weight of biogass is relatively small, 10 and the densities of the cellulose based waste and the compost are not too far from 1. In one embodiment of the invention, v9 is from about v4/2 to about 2*v4, such as about v4. The pretreated water from the channel may be distributed to ASBR and the compost basin at transfer rates v3 and v4 in a ratio of about 10:1; the activated sludge from ASBR may be distributed to 15 SBR and the channel at transfer rates v5 and v6in a ratio of about 10:1; the activated sludge from SBR may be transferred to ASBR at transfer rate v8 of about 0.02*v7. In any case, the following relations will approximately hold: v2+v6= v3+v4 for the channel; v4+v9 = v10 for the compost basin; v3+v8 v11 = v5+v6 for the ASBR; and v5+ v11 = v7+v8 for the SBR. In an important aspect of the invention, animal liquid waste flows through the purification system of the invention and provides safe water, for example as seen in Fig. 3, or in Fig. 1 in which waste liquid 7 provides safe water 10. Superb results of the system according to the invention are attained through 25 a plurality of tuned fractionating steps and a plurality of tuned backflows, as seen in Fig. 2: such a partition occurs in the channel reactor at the outlet of which a smaller part of the stream is removed (v4<v3), and the tuned backflows occur in ASBR from which a smaller part returns to the channel reactor (v6<v5), and in SBR from which a smaller part returns to the ASBR 30 (v8<v7); the ratios of v4/v3, v6/v5, and v8/v7 being important regulation parameters. WO 2017/203505 PCT/IL2016/051177 - 13 In one preferred embodiment of the invention, the system for treating livestock waste waters, including the facility and the process according to the invention, comprises additional stages of water purification according to the external requirements and according to the desired use of the final water 5 product; said additional stages preferably follow the aerobic treatment, for example the treatment in a SBR. Said additional stages preferably comprise filtration steps, such as sand filtration and reverse osmosis filtration (RO). In a preferred embodiment, water treated in a SBR flows to a sand filter and then to an RO system. The whole process, comprising a primary, anaerobic 10 stage (preferably employing a pretreatment channel and an ASBR) and a secondary, aerobic stage (preferably employing a SBR), thus comprises in one embodiment a tertiary stage (sand filter) and a quaternary stage (RO). Said quaternary stage usually employ