EN
The anaerobic-anoxic process has been proposed as an alternative to conventional anaerobic-aerobic process for biological phosphorus removal. In this process, phosphate-accumulating bacteria utilize nitrate or nitrite as an electron acceptor instead of oxygen, so phosphorus and nitrogen are removed simultaneously by one group of heterotrophic microorganisms. Advantages of this process are the possibility of saving COD and energy as well as reduction of sludge production. The paper reviews literature on the application of the denitrifying phosphorus removal process for treating municipal wastewater, analyses methods for determining the fraction of denitrifying phosphorus-accumulating organisms in P-removing sludge, and characterizes problems with bacteria isolation and identification.