OVERVIEW OF CHALLENGES IN PROVIDING ANAEROBIC WASTEWATER TREATMENT

The advantages of anaerobic treatment of wastewater are well known and the process has a long history of use for domestic wastewater treatment. Early systems consisting of solids capture/fermentation tanks often followed by soil application were the early choice of wastewater treatment systems. However, these systems were abandoned with the development of stricter effluent standards. Nonetheless, researchers continued to investigate the use of anaerobic processes for municipal wastewater treatment. Major progress was made with the development of the newer generation of high rate anaerobic reactor configurations, most notably the UASB process over 30 years ago. A key factor in the performance of any of the newer high rate anaerobic reactors treating sewage is temperature. It was the general consensus of most researchers and practitioners, that anaerobic treatment processes are only applicable to sewage treatment in warmer climates. This is somewhat fortuitous in that much of the tropical world is without any basic sanitation, and therefore anaerobic technology, being relatively simple and inexpensive, is most applicable for tropical areas. This led to several demonstration and full scale projects with promising results. More recently the role of anaerobic sewage treatment is being recognized for its role in sustainability. An anaerobic reactor as a core unit coupled to pre- and post-treatment systems to promote recovery of nutrients and polishing of effluent improves the sustainability of treatment systems. Related to sustainability is the recognition of the role of anaerobic treatment in decentralized wastewater treatment.