Biological denitrification of wastewater is a widespread technology for nitrogen removal from wastewater. Activated sludge technology is dominating over biofilm processes in practice. Recirculation and alternating processes are used to the same degree. The typical effluent quality that can be achieved on a long-term average is 4–10 mg/l of total nitrogen. Under certain circumstances effluent concentrations of 2–3 mg N/l can be obtained. Soluble organic nitrogen and nitrate are the dominating compounds in the effluent. Of these two, the soluble organic nitrogen content is difficult to control.
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© IWA Publishing 1991