Simultaneous removal of sulfate and organic matter by anaerobic submerged membrane bioreactor under haloalkaline conditions

SUMMARY Simultaneous Removal of Sulfate and Organic Matter by Anaerobic Submerged Membrane Bioreactor Under Haloalkaline Conditions In this thesis, submerged anaerobic membrane bioreactor was used to simultaneous remove organic matter and sulfate under haloalkaline condition. The enrichment of haloalkaliphilic microorganisms was done from the sediments of Van Lake at different points. The beginning of reactor operation was conducted after the enrichment of mixed culture. The operation of bioreactor was carried out throughout 380 days with eleven periods. Different ratio of COD/SO42- (1-12), hydraulic retention time (HRT) (7-15 day) and organic carbon sources (acetate, ethanol and mixture of ethanol/acetate) were assessed. The performance of reactor was followed in terms of the removal efficiencies of chemical oxygen demand, sulfate and total organic carbon and in parallel to sulfate reduction, the concentration of bisulphur was analysed. Additionally, pHs, alkalinity and conductivity of synthetic wastewater and influent were periodically determined. The influence of different operation conditions on microbial diversity was also determined. Sulfate removal did not occur in the periods when acetate was used as sole carbon resource. Ethanol was good carbon source for sulfate utilization, however, acetate formation from ethanol biotransformation was a limiting factor for COD removal. The simultaneous removal efficiency for both COD and sulfate was 69% when ratio of COD/SO42- of 1, HRT:10 day, the ratio of ethanol/acetate: 1/2. The highest COD removal was determined as 81,70% at period 11 where the ratio of COD/SO42- of 1, HRT:10 day and the ratio of ethanol/acetate:1/4 while the highest sulfate removal was about 70% at period 8 (P8) where the ratio of COD/SO42- of 1, HRT:10 day and the ratio of ethanol/acetate:1/1. Key Words: Submerged anaerobic membrane bioreactor, Electron donor, Sulfate removal, Haloalkaline condition