Abstract:

The concentrated liquid behind a landfill leachate membrane is a type of high-concentration organic wastewater generated during the leachate membrane treatment of landfills. It has a complex composition and is difficult to process via biodegradation. Because of its high chemical oxygen demand (COD), high ammonia nitrogen, high salt content, and other characteristics, the salt cannot crystallize and precipitate smoothly after reaching the saturated state, making it difficult to execute the follow-up mechanical vapor recompression process. To execute the follow-up treatment process smoothly, ferric chloride, aluminum chloride hexahydrate, polyaluminum chloride, and polyaluminum ferric chloride were used as coagulants; polyacrylamide was used as a coagulant aid; and the removal rate of COD was used as an evaluation parameter to coagulate the post-membrane concentrated liquid of a waste treatment plant in Jinan, and the optimal operating conditions were obtained. Results show that ferric chloride is the best coagulant. When FeCl₃ dosage was 0.64 g/L, polyacrylamide dosage was 4 mg/L, and pH was 6, the removal rate of COD was the highest (80.6%).

Key words: landfill leachate, DT effluent, coagulation, pretreatment