Gongye shui chuli (Jan 2024)
Treatment characteristics of the delayed stirring pelleting coagulation of landfill leachate
Abstract
Coagulation sedimentation is a critical pretreatment step in the advanced treatment of landfill leachate. Traditional coagulation processes for treating landfill leachate have drawbacks such as low water recovery,loose flocs,and low pollutant removal efficiency. A delayed stirring pelleting coagulation process of landfill leachate was put forwarded based on the theory of mechanical syneresis. Through long periods of high-intensity mechanical agitation,it could homogenize suspended solids. The results showed that the removal efficiency of SS,turbidity,and COD could reach 92.33%,99.92%,and 35.84% under optimal conditions of pH=12,stirring strength of 1 500 r/min,PAC and PAM dosage of 3 000 mg/L and 60 mg/L. The image particle measurement system revealed that under optimal conditions,the d50 of floc was 3.76 mm and the sedimentation velocity was 20.08 mm/s,which was approximately 60% higher than that of conventional coagulation. According to the floc sedimentation rate,projection area and effective particle size,the three-dimensional fractal dimension was 2.890 9 and the effective density was 0.087 6 g/cm3. It was found that the floc produced by delayed stirring pelleting coagulation had fast sedimentation speed and high density,and the supernatant recovery rate after floc could increase from 45% conventional coagulation to 85%.
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