Suitability of UASB Reactor System in Tropical Developing Countries like India

Tropical countries such as India have a lot of scope for anaerobic wastewater treatment due to the fact that for most part of the year temperature remains above 200C. This led to growing interest in developing new or modifying existing anaerobic wastewater treatment technologies. Maharashtra pollution control board (MPCB) has defined consent limits about the quality of wastewater from the industries under section 26 of the Water (Prevention and Control of Pollution) Act 1974. This made the treatment of effluent water from various industries mandatory. Having a lot of advantages such as less energy and very small sludge formation as compared to conventional wastewater treatment methods, anaerobic treatment is the obvious choice nowadays. The detailed advantages of anaerobic treatment over conventional methods are deeply covered in this paper. There are many types of anaerobic wastewater treatment processes depending on their application. A simple septic tank method has been used since ancient times. Since then there have been significant advances in reactor design. These include anaerobic fluidized bed (AFB), anaerobic fixed bed, sequencing batch reactor (SBR), upflow anaerobic sludge blanket (UASB), expanded granular sludge blanket (EGSB), etc. Among these UASB technology is the most widely used trend in recent years. UASB offers a continuous operation with large loading rates in short retention time. Gas generated in the form of methane can be used for energy generation. This paper reviews all the designs of UASB reactor and their suitability for application in tropical and subtropical regions. More emphasis is given on the applications of UASB in various industries. An attempt has been made to resolve most of the existing challenges in design as well as operation of UASB by reviewing recent work in this area. This will help in optimizing the current UASB technology.