Experimental study on detoxification of aged landfill leachate by coagulation process

4 kinds of coagulants were applied to treat aged landfill leachate, the influences of pH value and coagulants dosage on treatment effect were studied, and the biotoxicity and biodegradability of the landfill leachate before and after the treatment were estimated by photobacteria method and oxygen uptake rate method. The results showed that, ferric chloride and aluminum sulfate had good effects on aged landfill leachate treatment. When the pH values of the two coagulants were 4.0 and 5.0, the dosage were 1.0 g/L and 2.0 g/L, the removal rate of UV254 reached 70.0% and 61.7%, the removal rate of COD reached 44.7% and 48.3%, respectively. After the coagulation treatment by ferric chloride and aluminum sulfate, the relative luminosity of the water sample increased from 1.9% to 27.2% and 19.1%, the toxicity was decreased to a certain degree; furthermore, the oxygen uptake rate increased by 2.65 and 3.04 times respectively, which indicated that the biodegradability of the leachate was improved.