Diagnosis of treatment efficiency in industrial wastewater treatment plants: a case study at a refinery ETP.

Many industries employ the activated sludge process for biological removal of pollutants present in wastewater. Yet, treatment plants do notfunction at optimum potential. The biological component of such systems remains a black box, and reasons responsible for poor performance have not been identified. We have used genomic and physiological tools to understand the process and propose that analysis of catabolic signatures and nutrient levels, are crucial parameters in assessing and monitoring the performance of an effluent treatment plant. In this study, we use activated sludge collected from a refinery running at a capacity of 8 million metric tonnes of wastewater as a model. The presence of hydroxylases, oxygenases, and dioxygenases in the biomass was demonstrated by polymerase chain reaction and sequence analysis of aromatic-ring hydroxylating dioxygenase clones extracted from the metagenome, suggests the presence of hitherto unreported enzymes. The actual degradative state of the biomass was demonstrated by respirometric analysis using 11 substrates expected in refinery wastewater. Nutrient-levels required for the microbial population were estimated by on-site analysis. Diagnosis of the degradative potential of activated sludge can be carried out by incorporating these tools in regular monitoring procedures and can setthe rules for improving the efficiency of treatment