Pretreatment of nonbiodegradable landfill leachate by air stripping coupled with agitation as ammonia stripping and coagulation–flocculation processes

A combination process has developed as a pretreatment of non biodegradable leachate. The processes consist of air stripping coupled with agitation as a modified of ammonia stripping followed by coagulation–flocculation processes. The main aims of these processes are reducing a concentration of NH3-N and organic matter as well as enhancing the biodegradability of landfill leachate. Ammonia stripped by the airflow rate of 10 L min−1 at pH 11 for 3 h, while the agitation process applied to air stripping effluent for 2 h at the pH of 11.5 in 150 s−1 gradient velocity. NH3-N was removed at 96 % as removal ratio by the modified ammonia stripping in 5 h stripping time. Ferric sulfate, poly ferric sulfate and aluminum poly chloride was tested as a coagulant material in the coagulation process. Chemical oxygen demand (COD), suspended solids (SS), turbidity as well as the sludge ratios were discovered for each material operated under optimum condition of pH and dosage. The overall removal of NH3-N, COD, biochemical oxygen demand, total organic carbon, and SS obtained by these processes were 96.5, 71.5, 56.5, 48.5, and 96.5 %, respectively, at the corresponding biodegradable ratio was modified from 0.20 to 0.31.