Kinetics of nitrogen removal from sanitary landfill leachate.

Leachates from municipal landfill 'Lublinek' in Lodz city (Poland) were treated in two-sludge sequence batch reactor systems (type ND). The external carbon source--sodium acetate was used in denitrification. Two versions were tested--with and without supernatant recirculation from D-SBR to N-SBR. The 99% removal of inorganic nitrogen compounds was achieved in both versions. Due to recirculation, the buffering (by means of sodium bicarbonate) was not necessary. Kinetic models for nitrification and denitrification processes were proposed. Kinetic parameters of the models were estimated by the optimization method. The experimental results of both nitrification steps (oxidation of ammonia to nitrites and nitrites to nitrates) were best fitted with the interactive limitation model of nitrogen compounds and oxygen. The denitrification process was limited only by the concentration of nitrogen compounds.