Influence of chlorides and sulphates on quality of biological wastewater treatment using enzyme preparations

Abstract

Abstract The biological treatment method is widely used in Lithuania due to its high efficiency, low cost and suitability for treating various types of wastewater. After technological processes various mineral substances, such as chlorides and sulphates, get into water bodies. These substances are not removed from wastewater by the biological treatment method. The purpose of this study is to determine the concentrations of chlorides and sulphates, investigate the influence of enzyme preparations upon quality and energy consumption and assess energy changes in the trophic food chain during biological treatment. To analyse the mineral salt influence of the biooxidation process a series of laboratory tests was carried out: biochemical oxygen consumption (BOD), activated sludge concentration and other indexes. It is found experimentally that a 400 mg/1 concentration of chlorides disarranges the activity of microorganisms, and at a 700 mg/1 concentration active sludge is no longer suitable for biological treat...