Process for purifying, in particular, domestic waste water in a biological sewage treatment plant

摘要

The invention relates to a process for purifying, in particular, domestic waste water (effluent) in a biological sewage treatment plant having at least one activated sludge tank (10) and one secondary clarification tank (12), using a preferred additive which, even at peak loads, ensures that maximum values of carbon compounds and nitrogen compounds in the clarified waste water are complied with. It is provided that the waste water (14) is fed to the activated sludge tank (10) in the vicinity of the ground (22), the biologically purified waste water (28) is removed from the surface (64) of the activated sludge tank and the waste water (14) in the activated sludge tank (10) is conducted essentially free from vertical turbulence. It is particularly advantageous to treat the waste water (14) in the activated sludge tank (10) in the presence of silicate mineral dust, an alkali basalt having a mean grain size in the range of 15 mu m having a high fines content below 7 mu m being used. The dusty natural basalt has a sharp-edged angular shape and a bulk density in the range of 1.16 g/cm<3> and a compacted density in the range of 1.53 g/cm<3>. The BET surface area should be approximately 6 m<2>/g; the content of alkali metals and alkaline earth metals together should be at least 25% and of alkali metals alone at least 4%. The softening point should be above 800@C. A favourable sink behaviour in activated sludge tanks (10) is achieved when the density of the solid natural basalt is at least 2.9 g/cm<3>. <IMAGE>