INNOVATIVE APPROACHES FOR TREATMENT OF RETURN LIQUORS FROM ANAEROBIC DIGESTION

This paper provides a review of newer approaches for the management of reject water from anaerobic digestion (also referred to as either centrate or filtrate), with the focus being on side-stream biologically based systems. The increased use of dewatering after anaerobic digestion coupled with increasingly stringent effluent quality in terms of ammonia and total nitrogen has lead to a groundswell of research in the area of reject water treatment. A number of innovative treatment approaches have been developed in recent years that specifically target the reject water stream, some of which are physical/chemical in nature and others are biologically based. It is the latter group of processes, which include bioaugmentation (e.g. InNitri and BABE processes), nitritation (e.g. SHARON process) and anammox (combined SHARON/Anammox process, OLAND, CANON, STRASS), which has garnered the greatest interest due mainly to its potential cost effectiveness. This paper provides a review of these treatment approaches as well as estimates of the capital and operating costs of these processes that have been developed by others.