Process and apparatus for decreasing the pollutant content of waste water

摘要

The invention relates to a process for decreasing the pollutant content of waste water (effluent) which has already been pretreated. In order to specify a process and an apparatus for carrying it out by which the pollutant content of phosphorus compounds and nitrogen compounds and organic substances of a previously pretreated waste water can be decreased in a simple manner to values which permit problem-free discharge into municipal sewage treatment plants, it is proposed that the waste water proceeds through a multiplicity of purification stages in each of which it is applied from the top, distributed over a large surface, onto a packing formed of biomass, perculates between the packing particles by the action of gravity and drains off at the bottom in order to enter, if required, into the next purification stage, that to achieve an aerobic fermentation, an airstream is conducted through the packing of each purification stage from bottom to top, that a sump is formed downstream of the last purification stage, in which sump solids settle as sludge, that the purified waste water is conducted away above the sludge zone and that the biomass, after its extensive fermentation, is cyclically exchanged for fresh biomass.