Enviromental engineering - Essay Example

Chemical or biological processes can help specific sources of phosphorus as from wastewater treatment plants (Henze & Van Loosdrecht 155). Biological nutrient removal processes in the treatment of waste waters lead to environmental, operational and economic benefit. For this purpose, stricter rules are being implemented for removing phosphorus from waste water. The different nutrient removal processes are chemical, physical and biological. Various biological methods are available for removing both nitrogen and phosphorus.

The process of biological nutrient removal or BNR is based on a chain of biochemical reactions that convert nitrogen to another form. The main changes are nitrification and denitrification. “Nitrification is the conversion of ammonium, NH4+ to nitrite, NO2-, and finally to nitrate, NO3-“ (PWTB A-4). Denitrification is the process by which, without dissolved oxygen bacteria use nitrate as a terminal electron acceptor and convert it to nitrogen gas. Denitrification occurs rapidly when an external substrate like wastewater or methanol is present for bacterial growth.

Denitrification takes place slowly in the event of bacteria using nitrate in the absence of an external substance source. This is also termed as endogenous-level denitrification. The denitrification rates at endogenous level depend on sludge age and the active mass fraction of denitrifying bacteria (PWTB A-4). The effectiveness of the biological nutrient removal system is impacted by the “characteristics of the waste water influent to each zone of the process” (PWTB A-13). Both biological nitrogen removal and biological phosphorus removal can be carried out successfully only in the presence of adequate biodegradable organic substrate.

The efficiency of the biological phosphorus removal process differs according to the specific organic compound available in the anaerobic zone. There is reduced efficiency of nitrogen