Achieving Low Effluent Total Nitrogen Concentration

Full scale performance data and special surveys have been done to evaluate effluent total nitrogen performance in state of the art biological nitrogen removal facilities, and the removal of individual nitrogen species during treatment. Long term removal of ammonia N and particulate effluent nitrogen can be reliably done to effluent concentrations of less than 0.20 mg/L. Effluent nitrate and nitrite N provide a greater contribution to effluent total N and concentrations of less than 1.0 mg/L of oxidized N are possible. Tertiary denitrification filters with external carbon addition produce minimum effluent oxidized N. The effluent soluble organic nitrogen is the largest contributor to effluent total nitrogen and its concentration can be quite variable from site to site. Adding external carbon for denitrification and solids separation increases the greenhouse gas (GHG) emissions from nitrogen treatment to achieve low effluent total nitrogen concentrations. At high levels of nitrogen removal, the GHG production/N removed ratio increase by orders of magnitude.