Anaerobic digestion of wastewaters with high strength sulphates

The treatment of wastewaters anaerobically offers a number of significant advantages over aerobic treatment. However, presently anaerobic treatment is associated with a number of operational difficulties. One such difficulty is the inhibition of anaerobic bacteria by toxic materials. The inhibition of anaerobic bacteria by methanogenesis by hydrogen sulphide, a major end product of sulphate reduction which is produced when wastewaters containing high levels of sulphates are subjected to anaerobic digestion has been widely reported in literature. This has, therefore, hindered the application of this economical treatment method in the treatment of such strong yet potentially highly degradable industrial effluents. In an attempt to develop a technique for the use of anaerobic digestion in the treatment of wastewaters containing high strength sulphates, a system of two phase anaerobic digestion was investigated. This study demonstrated that when the operating parameters especially pH are carefully controlled, sulphate could be reduced in the acidogenic reactor without adversely affecting the normal process of acidogenesis. Phase separation could thus be said to be capable of successfully removing or reducing bacteria (SRBs) and methanogens. It is hoped that this process could enable wider application of anaerobic digestion to the treatment of industrial effluents especially those with high levels of sulphates, which were previously considered unsuitable for anaerobic treatment.