Biotechnological advancement of nitrogen and phosphorus removal from city sewage

Abstract

The present report discusses the theoretical basi s of nitrogen removal from wastewater, based on the processes of ammonification, nitrification, denitrification, and on a more recent direction called ANAMMOX-technology. The necessary conditions for this processes are considered. Biological phosphorus removal from wastewater through the proper use of microorganisms under different environmental conditions is noted. In this paper the recent advances of process design and operational optimization for nutrients removal are reviewed. Increasing volatile fatty acids is the main direction for higher efficiency of biological removal phosphorus. Products fermentation of primary sludge or feeding in anaerobic and anoxic zones is used for increase of volatile fatty acids. An important factor in increasing the degree of wastewater treatment with simultaneus lowering of energy costs is preliminary contact of initial sewage to circulating active silt in the conditions of aeration. It has been suggested to use a step feed denitrification and technology with cycling zones for lowering the energy consumption. Anaerobic, anoxic and oxic zones were designed and constructed in a single reactor. Although the volume of the reactor was limited and the capability of the process in th is reactor was reliable, it has a very good efficiency for removing phosphorus from raw wastewater. The high MLSS of activated sludge, fixed microorganisms and application membrane techology are used for significan tly increase of the capacity of plants while reducing their volume.