ABSTRACT
The composition of municipal wastewater varies very little geographically. An average composition encompassing all major components can therefore be indicated. A number of available treatment methods can be combined to reduce the concentrations in municipal wastewater of organic matter [biochemical oxygen demand (BOD5)], phosphorus, and nitrogen. Using a suitable combination of methods, it is possible to meet all realistic effluent standards. In industrialized countries, the treatment of municipal wastewater today is generally a combination of mechanical-biological treatment with nitrification and denitrification and chemical precipitation. By the combination of these treatment steps, it is possible to reduce the BOD5 and total nitrogen to about 10 mg/L and the phosphorus concentration to 1.5 mg/L or even lower. By the use of additional steps, it is of course possible to reduce the effluent concentrations further. Even a complete recycling of wastewater is possible by the combination of nine treatment steps.
