Anaerobic digestion of industrial and domestic wastewaters is an effective way of alleviating pollution problems. The treatment of vinasse, a residue of ethanol fermentation, and brewery/soft drink wastewaters was investigated by IPT for several years. This paper presents data and discusses the technical and economical feasibility of treating these wastewaters using UASB reactors.
With vinasse, it is possible to operate industrial plants with organic loading rates exceeding 15 kg COD m−3 day−l, removing 95% of the initial BOD. The produced gas can be used as a substitute for diesel oil in vehicles and also to produce steam, replacing bagasse. The pay-back period of the capital investment is estimated at around 4 to 5 years.
For brewery/soft drink wastewaters, it is possible to operate UASB reactors with a HRT of 6 hours, removing more than 90% of the initial BOD. The reactor showed a good capacity to handle temperature shocks.
Capital investments for both cases are presented in terms of total investment per kg of COD and m3 of reactor installed.