Claims:WE CLAIM:
1. An integrated up-flow anaerobic sludge blanket (UASB) process (100) comprising:
providing a Screen and Grit chamber (102) ahead of raw wastewater sump to remove inert material;
receiving by a sewage sump (104) the raw wastewater, and pumping it to UASB Reactor (106), the UASB reactor (106) configured for treating wastewater;
receiving by a bio-tower (108) treated effluent from the UASB reactor (106);
settling by a tube settler (110) biologically sludge from the Bio-tower (108);
chlorinating and de-nitrificating by a Chlorine Contact Tank (CCT) (112) of the treated sewage;
removing by a Pressure Sand filter (114) traces of suspended solids, turbidity & odor;
removing by a Dual Media Filter (116) suspended solids, turbidity and some part of colour and odour from treated sewage; and
storing in a storage tank (118) the treated wastewater.
2. The integrated UASB process (100) as claimed in claim 1, wherein the Screen and Grit chamber (102) includes a manually cleaned inclined Bar screen.
3. The integrated UASB process (100) as claimed in claim 1, wherein an integrated UASB reactor (106) consists of mainly feed distribution network at the bottom, Sludge blanket at mid height of the reactor and the gas, liquid, solid separator (GLSS) at the top of the reactor.
4. The integrated UASB process (100) as claimed in claim 1, wherein a feeding and distribution system is provided in the UASB reactor (106) for the waste water to be treated to the bottom of the UASB reactor (106); moving the waste water upwards through a layer of biomass sludge.
5. The integrated UASB process (100) as claimed in claim 1, wherein the UASB reactor (106) contains a gas liquid solid separation system to separate generated biogas from the sludge biomass and the treated liquid.
6. The integrated UASB process (100) as claimed in claim 1, wherein the UASB reactor (106) includes a modified reactor geometry, different from conventional reactors, wherein the modified reactor geometry provides an internal mixing, the modified reactor geometry includes a slanted baffle placed in the bottom of the UASB reactor (106).
7. The integrated UASB process (100) as claimed in claim 1, wherein the bio-tower (108) is a square or rectangular structure full of media over which the process flow is distributed, or “trickled”.
8. The integrated UASB process (100) as claimed in claim 1, wherein the Tube Settler (110) is in the form of square Hopper tank has been provided for settlement of biologically sludge from the Bio-tower (108).
9. The integrated UASB process (100) as claimed in claim 1 includes a lamella clarifier to remove suspended solids coming out from the bio-tower (108).
, Description:INTEGRATED UP-FLOW ANAEROBIC SLUDGE BLANKET (UASB) PROCESS
FIELD OF INVENTION
[001] The present invention relates to treatment of wastewater. Particularly, the present invention relates to an integrated modified up-flow anaerobic sludge blanket (UASB) process being provided with an aerobic biofilm reactor as the post treatment of anaerobic effluent.

BACKGROUND OF THE INVENTION

[002] Water scarcity is becoming an acute problem in several countries. Wastewater reuse can be a very good approach to conserve water particularly in areas of water shortage. Conventional sewage treatment processes involve high capital, maintenance and operation cost, huge energy requirements, which makes them unsuitable for use in developing countries. Anaerobic treatment is being increasingly used for its several advantages over aerobic processes like (a) reduced cost and low energy requirement due to no requirement for aeration, (b) less sludge production and the sludge produced can be directly dried on sludge drying bed without further treatment due to better dewatering ability, (c) low nutrient requirement, (d) production of valuable by-products in form of CH4, (e) Organic loading on the system is not limited to oxygen supply hence higher loading rate as compared to aerobic processes can be applied, (f) less land area required, (g) Non-feed conditions for few months do not affect adversely to the system.

[003] The classical anaerobic processes are septic tanks or imhoff tanks, anaerobic pond etc. However, currently high rate anaerobic reactors like- anaerobic filter (AF), anaerobic fluidized and expanded bed reactors (FBR), up-flow anaerobic sludge blanket (UASB) reactor, anaerobic baffled reactor (ABR), hybrid up-flow anaerobic sludge blanket reactor (HUASB) have been commonly used for wastewater treatment. Among them, UASB is the most widely and successfully used high rate anaerobic reactor for treating different types of wastewater throughout the world since 1980s. However, conventional UASB cannot produce good quality effluent while using for the treatment of low strength wastewater such as municipal sewage.

[004] Moreover, the effluent of anaerobic reactor does not comply with the effluent discharge standards established by various environmental agencies. Therefore, the anaerobic effluent requires further treatment (post treatment) in order to remove oxygen demand of remaining organics; suspended solids; pathogens and odours. The post treatment should be simple, compact and inexpensive so that the overall anaerobic system still remains economically attractive. Several post treatment options have been studied for the treatment of anaerobic effluent such as, biological, phisico-chemical (coagulation flocculation) or advanced oxidation processes (AOPs). These post treatment options may be very efficient but, large area requirement, high dose and cost of chemicals used, large sludge volume generation, high initial investment makes these technologies unaffordable especially for developing countries. Therefore, there is a need to develop post treatment process for anaerobic effluent keeping in view of total investment including capital cost, operation and maintenance cost and land requirement.

[005] High-rate anaerobic reactors especially up-flow anaerobic sludge blanket (UASB) has been used since last few decades for treating industrial wastewater as well as domestic sewage. However, the efficiency of UASB reactor is quite low for the treatment of low strength wastewaters (LSWs) due to less biogas production leading to poor mixing. Occasionally, the UASB reactor effluent contains residual organic matter, high pathogen content and low dissolve oxygen. Therefore, post treatment of UASB effluent is required to meet the discharge standard.

OBJECTIVE

[006] The prime objective of the present invention is to provide a novel Anaerobic-Aerobic Biofilm Technology for the treatment of low strength wastewater.

[007] Another object of the invention is treatment of low strength wastewater and to produce the treated effluent of reusable quality.

SUMMARY OF THE INVENTION

[008] The present disclosure relates to an integrated up-flow anaerobic sludge blanket (UASB) process (100) including: providing a Screen and Grit chamber (102) ahead of raw wastewater sump to remove inert material; receiving by a sewage sump (104) the raw wastewater, and pumping it to UASB Reactor (106), the UASB reactor (106) configured for treating wastewater; receiving a bio-tower (108) treated effluent from the UASB reactor (106); settling by a tube settler (110) biologically sludge from the Bio-tower (108); chlorinating and de-nitrificating by a Chlorine Contact Tank (CCT) (112) of the treated sewage; removing by a Pressure Sand filter (114) traces of suspended solids, turbidity & odor; removing by a Dual Media Filter (116) suspended solids, turbidity and some part of colour and odour from treated sewage; and storing in a storage tank (118) the treated wastewater.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[009] Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings of the exemplary embodiments and wherein:
Fig. 1: A process and instrumentation diagram associated with components of an up-flow anaerobic sludge blanket (UASB) process 100 in accordance with an embodiment of the present disclosure
Fig 2: A schematic of the up-flow anaerobic sludge blanket (UASB) process 100

[0010] The figure(s) depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENT INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS

[0011] The present invention, now be described more specifically with reference to the following specification.

[0012] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.

[0013] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.

[0014] Upflow anaerobic sludge blanket technology, normally referred to as UASB, has proven effective for the treatment of medium strength wastewaters (MSWs) and high strength wastewaters (HSWs). The potential of UASB reactor is not restricted for the treatment of MSWs and HSWs. The UASB reactor can also be useful for low strength wastewater (LSW) treatment. However, despite several advantages many research have pointed out that UASB reactors have some inherent limitations especially for the treatment of LSW (LSWs are those which contains COD concentration below 2,000 mg/L). Sewage can be considered as an example of low strength complex wastewater which also contains significant fraction of suspended solids (SS).

[0015] The presence of SS in wastewater affects the UASB process adversely as degradation of particulate matter is difficult as compared to soluble organic matter. The presence of SS also decreases sludge activity due to adsorption and entrapment on granular surface of sludge biomass, thereby inhibiting granulation process in UASB reactor. Thus, the efficiency of the UASB system is limited as it has low SS removal capability mainly for the treatment of LSWs. The diffusion rate of substrate to anaerobic biomass is also lower in this condition.

[0016] Previous investigation showed that mixing is important to improve reactor efficiency. During the treatment of MSWs and HSWs, gas production inside the UASB reactor provides good mixing. Well mixed conditioned lead to higher dispersion thus resulting in limited plug-flow behavior of the sludge bed. Turbulence of sludge bed is enhanced under this condition due to collision of the gas bubbles with the granules which is not achieved during the treatment of LSW as low volume of biogas is produced.

[0017] In an UASB reactor, low mixing may cause channeling of wastewater through the bed and therefore a poor wastewater–sludge contact, which results in low treatment efficiencies. Dilute complex wastewaters provides low mass transfer between wastewater and biomass due to the presence of considerable amount of particulate matters. Therefore, sufficient mixing is essential in order to eliminate mass transfer limitations in microbial aggregates. Moreover, the effluent of UASB reactor does not comply with the effluent discharge standards established by various environmental agencies. Therefore, the effluent of UASB requires further treatment (post treatment) in order to remove remaining organics.

[0018] Fig. 1 illustrates a process and instrumentation diagram associated with components of an integrated up-flow anaerobic sludge blanket (UASB) process 100 in accordance with an embodiment of the present disclosure. In an example, the integrated UASB process 100 is associated with the following components:

- Screen & Grit Chamber 102
- Sewage Sump 104
- UASB Reactor 106
- Bio Tower 108
- Tube Settler 110
- Chlorine Contact Tank (CCT) 112
- Pressure Sand Filter 114
- Dual Media Filter 116
- Treated Sewage Storage Tank 118

[0019] Fig. 2 illustrates a schematic of the integrated up-flow anaerobic sludge blanket (UASB) process 100. In an example, Screen and Grit chamber 102 has been provided ahead of the raw wastewater sump to remove the inert material. The Screen chamber 102 shall be provided with manually cleaned inclined Bar screen. The quality and quantity of raw wastewaters may fluctuate. Raw wastewater / sewage sump 104 has been provided for receiving the raw wastewater and pumping it to the UASB Reactor 106.

[0020] The integrated UASB reactor 106 consists of mainly feed distribution network at the bottom, Sludge blanket at mid height of the reactor and the gas, liquid, solid separator (GLSS) at the top of the reactor. In the UASB process 100, the bacteria responsible for digestion are present in the form of sludge blanket. The bacteria grow and reside as bacterial flocs suspended in the up- flow effluent stream. The bacteria consume organic content of wastewater and metabolize it to produce biogas and biomass. A feeding and distribution system is provided in the UASB reactor 106 for the waste water to be treated to the bottom of the UASB reactor 106; moving the waste water upwards through a layer of biomass sludge.

[0021] The UASB reactor 106 operates in the mesophillic range of temperature, i.e. 28° - 40°C. The pH inside the UASB reactor 106 is usually kept around 7.2 while proper ratio of volatile acid and alkalinity is maintained. Biogas generated is collected at the top (collection system) of the UASB reactor 106 and send to the flare stack. In an example, the UASB reactor 106 contains a gas liquid solid separation system to separate generated biogas from the sludge biomass and the treated liquid. The anaerobically digested effluent is collected from the network of gutters and launders and taken to the aeration tank for further treatment. The excess sludge from the bottom of the UASB reactor 106 is periodically taken out and sent to the sludge handling facility. The treated effluent from the UASB reactor 106 is then taken to the Bio-tower 108.

[0022] In an example, the UASB reactor 106 includes a modified reactor geometry, different from conventional reactors, wherein the modified reactor geometry provides an internal mixing. Further, the modified reactor geometry includes a slanted baffle placed in the bottom of the UASB reactor 106. The baffle is a rigid plate, which is fixed between two opposite vertical walls. The baffle is introduced having an angle of 5.7 degree with the vertical wall bottom and a top. The slanted baffle in the UASB reactor 106 enhance the mixing of the incoming liquid with the active sludge biomass. In an example, the hydraulic retention time of the UASB reactor is 8 hours or less.

[0023] For the post treatment of UASB effluent, the developed Bio-tower 108 as biofilm reactor is relatively simple treatment units. In an example, the bio-tower 108 is a square or rectangular structure full of media over which the process flow is distributed, or “trickled”. The media is used as a surface on which to grow a biological mass which will contain and support a population of microorganisms which perform the actual treatment that takes place in the Bio-tower 108. The media is designed to provide the desired characteristics of ventilation, durability, and surface area. The new plastic media used in the Bio-tower 108 provides much greater surface area per unit of volume.

[0024] The Tube Settler 110 in the form of square Hopper tank has been provided for settlement of biologically sludge from the Bio-tower 108. The tank shall be provided with PVC Tube Dek for improving the Settling Area. The settled sludge at the bottom of the settling tank will be taken on Sludge Drying Beds. This sludge being fully mineralized is suitable for sun drying on sand drying beds.

[0025] In an example, the integrated UASB process 100 includes a lamella clarifier to remove suspended solids coming out from the bio-tower 108. The treated sewage will further be subjected to chlorination for de-nitrification of the treated sewage in the Chlorine Contact Tank (CCT) 112. Chlorine solution will be added to the treated Sewage. Chlorine dose will be adjusted to maintain the residual chlorine concentration of 0.5-1.0 ppm.

[0026] The Pressure Sand filter 114 has been provided for removal of traces of suspended solids, turbidity & odor. The Pressure Sand Filter 114 shall be a cylindrical mild steel pressure vessel with dished ends. Anthracite & filter sand has been provided as the filtering media.

[0027] The Dual Media Filter 116 is used for removal of suspended solids, turbidity and some part of colour and odour from treated sewage. It contains anthracite along with fine sand reinforced by marbled and gravels. During the filtration cycle the largest particles are strained out by the anthracite then the sand traps the rest of the particulate matter though a combination of adhesion and straining. Since the particles in the biologically treated water are filtered out at various depths in the dual media filter 116, the filter 116 does not clog as quickly as all of the particles were caught by the top layer.

[0028] A storage tank 118 has been provided to store the treated wastewater. It is a covered reservoir to cater for fluctuations in demand.

[0029] In an example, the UASB process 100 has been developed for the treatment of low strength wastewater; comprises of an anaerobic reactor followed by a novel biofilm technology which has been developed for the post treatment of anaerobic effluent; requires 60% less power as compare the aerobic system; generates an effluent having BOD of <15 ppm and COD of <30 ppm; generates a effluent having DO concentration <2.2 ppm; generates a effluent which can be used in high end industrial as well as domestic application.

[0030] It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims.