Biological treatability of domestic and industrial wastewaters in a treatment plant

Abstract

Urban development produces wastewaters with flow and/or concentration peaks which prejudice the well functioning of a wastewater plant designed for influent categories characterized by certain domains of composition and concentration. This study aimed to investigate the conventional physico-chemical and biological treatability parameters of the influent and the removal efficiency of the treatment plants: high carbonic loading, chemical oxygen demand (COD), and low biodegradability as BOD5/COD (biochemical oxygen demand/chemical oxygen demand) ratio. The improvement of the biological biodegradability parameters in order to obtain a proper activated sludge was achieved by optimal oxygen and nutrients addition. Molasses addition to correct the BOD5/COD ratio to values ≥ 0.4, determines the increase up to 60-80% of biodegradable organic matter mineralization. COD efficiency removal increases by 1-20% vs. the results obtained for oxygen deficit and/or low biological treatability.