摘要：

混凝沉淀在垃圾渗滤液的深度处理工艺中是非常必要的预处理环节。传统的混凝工艺处理垃圾渗滤液普遍存在水资源回收率低、污染物去除率低、絮凝体松散等缺点。基于收缩脱水絮体致密化理论，提出了垃圾渗滤液的延时搅拌造粒工艺，通过长时间高强度的机械搅拌实现悬浮物的均一化。研究结果表明，在pH=12、搅拌强度为1 500 r/min、PAC和PAM投加量分别为3 000 mg/L和60 mg/L的最佳条件下，SS、浊度、COD的去除率分别可达92.33%、99.92%、35.84%。通过图像粒子测算系统测得最佳条件下絮凝体d ₅₀为3.76 mm，沉速为20.08 mm/s，与常规混凝相比，沉速提升约60%。基于絮体沉速、投影面积、有效粒径等数据，计算得到三维分形维数为2.890 9，有效密度为0.087 6 g/cm³。延时搅拌造粒生成的絮体沉速快、密度大，混凝后的上清液回收率可由常规混凝的45%提升至85%。

关键词: 垃圾渗滤液, 延时搅拌造粒, 分形维数, 有效密度

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 d ₅₀ 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%.

Key words: landfill leachate, delayed stirring pelleting coagulation, fractal dimension, effective density

中图分类号: 

• X703.1