TREATMENT OF WASTE WATER

摘要

An activated sludge tank for treating waste water, e.g. municipal sewage, has a biofilter (31) located in the first 50 % of the length of the tank, spaced from the inlet end (25) by a first activated sludge zone, and occupying less than 40 % of the length of the tank. All the water passes through the biofilter. A second activated sludge zone (26), which is aerated, is located on the outlet end side of the biofilter (31). In the tank the activated sludge has typically an average concentration in the range of 1 to 6 g/L, and the biofilter has a biomass concentration of at least 10 g/L. The presence of the biofilter (31) increases the removal of micro-organic components such as steroid oestrogens.