Anaerobic pilot-scale treatment of a tetrachloethylene-rich synthetic effluent with morphological study of granules

A laboratory scale study was conducted to study the biodegradation of tetrachloroethylene (PCE) in Anaerobic Hybrid Reactor (AHR). The acclimatization study revealed that more than 99.85% of PCE can be removed at influent PCE and COD concentration of 50 mg/l and 2000 mg/l respectively at 24 hours of hydraulic retention time (HRT). Distribution of granules in the sludge bed dictated that the granules of larger diameter (> 2mm) were found to mainly be concentrated at the lower active zones while smaller sized granules (< 0.5-2 mm) were at the top and middle zones of the sludge bed. Scanning electron microscope (SEM) study of the granules demonstrated predominance of Methanosarcina and Methanothrix types of bacterial species on the surface of granules.