ANAEROBIC-DIGESTION OF WASTEWATERS WITH HIGH-STRENGTH SULFATES

The treatment of wastewaters anaerobically offers a number of signific ant advantages over aerobic treatment. However, presently anaerobic tr eatment is associated with a number of operational difficulties. One s uch difficulty is the inhibition of anaerobic bacteria by toxic materi als. The inhibition of anaerobic bacteria by methanogenesis by hydroge n sulphide, a major end product of sulphate reduction which is produce d when wastewaters containing high levels of sulphates are subjected t o anaerobic digestion has been widely reported in literature. This has , therefore, hindered the application of this economical treatment met hod 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 hig h strength sulphates, a system of two phase anaerobic digestion was in vestigated. 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 w ith high levels of sulphates, which were previously considered unsuita ble for anaerobic treatment.