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 treatment. Also, we investigated the effect of a ferment preparation “Roebic” on effluence of sewage treatment. In a tank with an enzyme the total amount of energy after treatment increases by 5–30 %. It is determined by calculating the accumulation of energy in an active‐sludge system that an enzyme preparation increases the energy levels of the system.
Highlights
The problems of the protection of water bodies are closely related to treatment of wastewater discharged to them, municipal wastewater treatment facilities in most towns of Lithuania cannot ensure the quality of treatment
The biological treatment method is widely used in Lithuania due to its high efficiency, low cost and suitability for treating various types of wastewater
The purpose of this study is to determine the concentrations of chlorides and sulphates, investigate the influence of an enzyme preparation upon quality and energy consumption and assess energy changes in the trophic food chain during biological treatment
Summary
The problems of the protection of water bodies are closely related to treatment of wastewater discharged to them, municipal wastewater treatment facilities in most towns of Lithuania cannot ensure the quality of treatment. The biological treatment method is widely used in Lithuania due to its high efficiency, low cost and suitability for treating various types of wastewater. Biochemical wastewater treatment processes are most regulated in active-sludge facilities. Biochemical wastewater treatment processes are very complex and depend on a number of factors, including the chemical composition and concentration of organic matter in wastewater, water temperature and pH, and the content of toxic substances in water [1]. 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. Chlorides get into water both with domestic and industrial wastewater because chlorine and chlorine compounds are used for rendering wastewater harmless [2]. Chlorine compounds are used to destroy pathogenic microorganisms, to remove odours in slaughterhouses and fish-processing enterprises, to salt foodstuffs in food industries, etc
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