Experiences and potential of anaerobic wastewater treatment in tropical regions

In this article an overview is given on the experience with anaerobic treatment of domestic wastewater in the tropics, with emphasis on the situation in India. Some design criteria and their impact on the costs of UASB reactors are discussed. The operational results of a number of full-scale reactors are presented. The applicability of the UASB, in combination with different post-treatment units to comply with a variety of effluent standards is compared with other systems. From the available data it is concluded that, if nitrogen removal is not required, a UASB system, followed by a polishing pond, is a relatively simple, affordable, and manageable wastewater treatment system. Trickling filters may follow UASB treatment if effluent standards require removal of TKN. The inclusion of UASB reactors in wastewater treatment schemes allowing for total nitrogen removal still needs further study.