Title of Invention

AN IMPROVED ANAEROBIC REACTOR USEFUL FOR TREATMENT OF BIODEGRADABLE WASTEWATER

Abstract

An improved anaerobic reactor useful for treatment of biodegradable wastewater characterized by hopper bottom collection and equalization reactor (1) with an inlet (1) provided at minimum 0.25 m above the support media in reactor (2), the said reactor (1) is connected to a reactor (3) through bottom and set of inclined tubes (2) having inclination angle of minimum 45° to the horizontal, the said hopper bottom reactor (3) is connected to hopper bottom reactor (2) packed with inert conventional support media through bottom, outlet (5) has been provided in reactor (2) at the level of the said support media which in turn is connected to conventional gas trapping system (6), outlets (7) are also provided to the said reactors at the top for the collection of gas and a sludge removal valve (8) is provided to the bottom of the said reactor.

Full Text

The present invention relates to an improved Anaerobic Reactor useful for Treatment of Biodegradable Wastewater Anaerobic biological treatment system is conventionally adopted for the treatment of strong & medium strength biodegradable wastewaters due to its cost-effectiveness. Anaerobic process has several merits mentioned hereunder: » High efficiency of wastewater treatment t Low production of excess biological sludge • Low nutrient requirements « No external oxygen requirement • Production of biogas having appreciable fuel value Since the volatile solids present in the wastewater are converted to high energy level compounds e.g.- methane, carbon dioxide and water in anaerobic treatment, quantity of sludge production is very low as compared to aerobic process thereby reducing the cost of disposal. Methane produced has a definite economic value as fuel, and can be used as a source of energy for generation of both heat and power. The stabilized sludge in anaerobic systems can be free from strong or foul odours. It can be used for land application as ultimate disposal because the digested sludge contains plant nutrients. Pathogens are also destroyed to a high degree during the anaerobic process. Among notable disadvantages, the process has low synthesis/reaction rate hence require long start up periods and recovery from upset conditions is difficult. Special attention is, therefore, warranted towards, controlling the factors that affect process adversely; important among them being environmental factors such as temperature, pH and concentration of toxic substances. The conventional anaerobic reactor systems in practice are divided into two major categories: • Suspended growth system (SGS) • Attached growth system (AGS) The anaerobic reactor systems that are conventionally adopted are: • Anaerobic lagoons • Anaerobic activated sludge • Anaerobic filters • Anaerobic contact process • Up flow Anaerobic Sludge Blanket(UASB) reactor • Expanded bed and fluidized bed reactor Each type of system has its advantages but is also associated with certain drawbacks. Suspended growth anaerobic reactor such as UASB or moving bed reactors are susceptible to hydraulic overloading which may result in biomass washout. It is less suitable for organic overloading and has the lowest degree of contact between wastewater and biomass. Problem such as channeling (short circuiting), hampered sludge mixing, clogging etc. are associated with attached growth systems. Anaerobic reactors used for the biological treatment of wastewater face problems due to presence of suspended solids in raw effluent. The efficiency of reactors get impaired, due to high concentration of suspended solids in the influent wastewater. In an anaerobic filter, the inert support media is provided, in the form of packing, to support the attachment of biomass. When the wastewater passes through this packed media, suspended solids present in the wastewater may develop progressive clogging of the packed bed and preferential hydraulic pathways may be created. In an Up flow Anaerobic Sludge Blanket Reactor (UASB), which operates entirely as a suspended growth system, availability of sludge, with good settling properties is the most critical parameter. The operational stability and efficient performance of UASB system is basically dependent, on the cultivation of granular and flocculated sludge with good satiability and high methanogenic activity. However, low hydraulic retention time (HRT), with high flow velocity, causes loss of biomass from reactor and imparts shorter contact time between substrate and microorganisms resulting in decreased removal efficiency of organics. Fixed Film Fixed Bed (FFFB) reactor systems are observed to be ideally suited for treating majority of wastewaters that respond to biological degradation due to following advantages • Recycle of effluent or solids to the reactor is not essential as biological solids are retained in the reactor and are not lost with the effluent » Greater resistance to periodic hydraulic or organic overload » Relatively rapid restart due to attached biomass and the reactor can be emptied and filled to remove excess solids or toxic materials » Smaller reactor volume because of higher specific surface area of the medium • Flexibility of operation : The reactor can operate as a digester, since removal of media is possible The FFFB reactor systems are also associated with following drawbacks • Clogging of packed media due to suspended solids in raw effluent • Short circuiting of wastewater flow, through the packed media, due to clogging • Inadequate mixing and therefore loss of reactor volume due to dead spaces The main object of the present invention is to develop an anaerobic reactor system utilizing the basic principles of FFFB system, which reduces the possibilities of washout of biomass leading to suspended biomass production, reduces the chocking of media due to removal of suspended solids and, ensures better contact between biomass and wastewater to be treated. "Ihis reactor configuration integrates inclined tube settlers, with a FFFB reactor, which imparts pretreatment to incoming wastewater by reducing suspended particulate load carried along with wastewater. This partial treatment, reducing suspended solids concentration, prevents the clogging problem of media, and then ensures longer working span of the rector system. Availability of maximum area for fixed film formation with minimum floor area requirement, ease of collection of biogas generated in the system and requirements of minimum pumping energy are some of the major considerations incorporated in the development. The system has been designed to achieve better contact probability between wastewater and biomass so that the configuration will contribute to high efficiency even at lower detention times. Fig 1 & 2 of the drawing accompanying this specification shows sectional elevation of the reactor. Accordingly the present invention provides an improved anaerobic reactor useful for treatment of biodegradable wastewater characterized by hopper bottom collection and equalization reactor (1) with an inlet (1) provided at minimum 0.25 m above the support. media in reactor (2), the said reactor (1) is connected to a reactor (3) through bottom and set of inclined tubes (2) having inclination angle of minimum 45° to the horizontal, the said hopper bottom reactor (3) is connected to hopper bottom reactor (2) packed with inert conventional support media through bottom, outlet: ([5) has been provided in reactor (2) at the level of the said support media which in turn is connected to conventional gas trapping system (6), outlets (7) are also provided to the said reactors at the top for the collection of gas and a sludge removal valve (8) is provided to the bottom of the said reactor (1). In a preferred embodiment of the invention, raw wastewater after equalization is pumped to the inlet chamber of reactor 1. This is the first chamber in the three chamber reactor and the wastewater enters into the reactor from the top of this chamber. This reactor 1 is connected to the reactor (3) through inclined tubes. Hopper bottom is provided at the bottom of the chamber for collection of sludge. The function of reactor 1 is to provide partial equalization for incoming wastewater before entering the inclined tube modules from the bottom of reactor (1). In another embodiment of invention the wastewater enters the inclined tubes from reactor (1). The tube modules, supported on the side supports (corbels) provided on the side walls, cover the entire plan area of the middle reactor. It consists of PVC tubes fitted at an angle of 45 to 60 degrees to horizontal. These inclined tubes run throughout the middle chamber connecting first and third chambers. The suspended solids are arrested in tubes due to differential in velocities of wastewater and solids. The clarified wastewater moves upward in the tubes and the separated solids descend down, in to the hopper, provided at bottom of reactor ( 1). The sludge so formed can be flushed out of the reactor as and when needed. In still another embodiment of the invention the partially treated wastewater with minimum concentration of suspended solids from the tubes gets collected in the reactor (3). The function of this chamber is to collect pretreated wastewater and feed it to the media chamber uniformly. ;In yet another embodiment of the invention wastewater enters reactor (2) from the bottom of reactor (3). The reactor (2), provided for biological treatment, is sandwiched between first and third reactor and is filled with inert porous media e.g. refractory bricks. Reactor (2) provides unnecessary surface area for the formation of bibful on the porous media surface and outside tube (surface. Wastewater gets contacted with this biomass for mistreatment during its upward flow in the reactor. Hoppers at reactor 1, 2 & 3, provided at the bottom of respective tanks, concentrate the sludge for effective dislodging operation. The hoppers are provided with side slope of 45 to 50 degrees. This provision helps in providing smooth and trouble free operation of the reactor. In yet another embodiment of the invention, the free space above the liquid level in all the reactors forms biogas collection reactor and collects the biogas produced during the anaerobic degradation of organic matter. A trap is provided at the outlet of the reactor to separate the treated wastewater from the gas before its collection. The invention will now be described with the help of the accompanying drawings. The device Shown in the drawings is an illustration of the embodiment of the invention. Fig. 2 of the drawing is a perspective view of one embodiment of the invention. Sewage enters at the top of the reactor (1) and rises up under hydrostatic pressure through inclined tubes (2) into reactor (3). While passing through inclined tubes the suspended solids are arrested in the tubes. This partially treated effluent is collected into the reactor (3). This partially treated wastewater then passes to reactor (2) from the bottom connection (4), so that it comes in contact with the packed medium and with outer surfaces of the tubes under the upward flow conditions. Bibful developed and retained on the outside surfaces of the tubes and the packed porous media, provides fixed film for biological treatment in this anaerobic reactor system. In this stage the bacteria are retained in the medium and are not washed off in the effluent, so that mean cell residence time (6c) of the order of 100 days can be achieved. Treated effluent flows out of the reactor from the top (5) of the reactor (2). Water seals are provided to the influent as well as effluent pipes so as to restrict the entry of air. This treated effluent enters the trap (6) at the top and flows out. Gas produced during the anaerobic degradation of wastewater is collected in the gas collection network (7), provided at the top of reactors 2 & 3. This collected gas, after reaching the pressure more than atmospheric pressure, rises through the nozzles provided at the top(7) and get collected. Suspended solids separated from the raw effluent collected in hopper bottom in reactor (1) and can be withdrawn through a valve (8). The main advantages of the invention are * Removal of suspended solids from the raw wastewater, before reaching to the biological treatment in a fixed film system, so that probability of clogging of reactor is reduced * Due to reduced clogging of the reactor the wastewater has better contact with biomass in fixed film, leading to higher efficiency of treatment » Treatment efficiency is high even with lower detention times for medium strength wastewaters * The flow pattern in the reactor is uniform as the turbulence and eddies generated at the inlet are dampened in reactor (l) » The system satisfactorily withstands fluctuating organic loads and can recover from shock loads within a reasonable period of time, yet yielding consistent quality of effluent. We Claim: 1. An improved anaerobic leactor useful for treatment of biodegradable wastewater characterized by hopper bottom collection and equalization reactor (1) with an inlet (1) provided at minimum 0.25 m above the support media in reactor (2), the said reactor (1) is connected to a leador (3) through bottom and set of inclined tubes (2) having inclination angle of minimum 45° to the horizontal, the said hopper bottom reactor (3) is connected to hopper bottom reactor (2) packed with inert conventional support media through bottom, outlet (5) has been provided in reactor (2) at the level of the said support media which in turn is connected to conventional gas trapping system (6), outlets (7) are also provided to the said reactors at the top for the collection of gas and a sludge removal valve (8) is provided to the bottom of the said reactor (I). 2. An improved anaerobic reactor as claimed in claim 1, wherein the inclined tubes made of PVC material are placed between rectors 1&3 have an angle of 45° to 60 " 3. An improved anaerobic reactor as claimed in claim 1&2 wherein the support medium in reactor (2) comprises bricks or other inert porous material. 4. The reactor claimed in claims 1 to 3 wherein the side slope of hopper is 15 to 50 degrees. An improved anaerobic lector useful for treatment of biodegradable wastewater substantially is herein described with reference to the drawing accompanying the specification..

Documents:

208-del-2000-abstract.pdf

208-del-2000-claims.pdf

208-del-2000-correspondence-others.pdf

208-del-2000-correspondence-po.pdf

208-del-2000-description (complete).pdf

208-del-2000-form-1.pdf

208-del-2000-form-19.pdf

208-del-2000-form-2.pdf

208-del-2000-form-3.pdf