Development of Sludge Bed in Upflow Anaerobic Reactors Treating Combined Industrial Effluent

In this study the effect of development of sludge bed on the efficiency of Upflow Anaerobic Sludge Blanket (UASB) and Upflow Anaerobic Sludge Filter (UASF) reactors, operating at HRTs 3 to 12 h and sludge age of 30, 60, 90, 0 and 150 days was investigated. The effect of temperature on the granulation of UASB sludge was more pronounced as compared to the attached microbial growth in the UASF. For UASB reactor, average concentrations of VSS and TS increased steadily up to sludge age of 120 days, beyond which VSS and TS contents decreased significantly due to sludge liquidation. For UASF reactor, average concentration of VSS increased steadily even beyond day 120, whereas average TS content increased from day 30 to day 60 and it decreased after 60 to day 90, mainly attributed to the expansion in the sludge height due to fluidization of the bed. XRD analysis of the UASF sludge showed the presence of expanding clays revealing its additional absorption capability. Fuoraphyllite and Albite precipitation in reaction with Calcium and Phosphate related to excellular polymers of the microbial shell structure, showed the extended growth of microorganisms during sludge granulation in the UASB reactor.