城市污水含砂特征及不同沉砂池除砂效率研究

Characteristics of Grit Distribution in Municipal Wastewater and Grit Removal Efficiency of Different Grit Chambers

为明确我国城市污水含砂特征,向除砂工艺优化设计提供参考,采集了6座不同城市污水处理厂的沉砂池进出水,分析了砂粒分布特征,并计算了沉砂池的除砂率。结果表明,城市污水含砂量介于1.28~80.96 mg/L之间,粒径>212μm的砂粒(粗砂)占22.25%~74.14%;各污水厂进水含砂量及粒径分布特征均存在明显差异。各污水厂使用中的曝气沉砂池或旋流沉砂池实测除砂目标粒径介于150~212μm之间,加权平均除砂率介于9.16%~52.02%之间。降低旋流沉砂池表面负荷至60 m/h以下,或者延长曝气沉砂池停留时间至10 min以上,可以将沉砂池除砂精度提升至150μm以下,并可有效提升沉砂池加权平均除砂率。

This paper collected the wastewater samples from the inlet and outlet of grit chambers in six different municipal wastewater treatment plants,analyzed the distribution characteristics of grit particles,and calculated the grit removal efficiency of the grit chambers,so as to investigate the characteristics of grit distribution in domestic municipal wastewater and provide reference for optimizing the design of grit removal process.The grit concentration in municipal wastewater ranged from 1.28 mg/L to 80.96 mg/L,and the grit with particle size greater than 212μm(coarse grit)accounted for 22.25%to 74.14%.There were obvious differences in the distribution of grit concentration and particle size in the influent of each wastewater treatment plant.The measured target grit removal diameter of the aerated grit chambers and the vortex grit chambers in each plant was between 150μm and 212μm,and the weighted average grit removal rate ranged from 9.16%to 52.02%.The target grit removal diameter of these chambers could be improved to less than 150μm,and the weighted average grit removal rate could be significantly increased by reducing the surface load of the vortex grit chambers to less than 60 m/h or extending the residence time of the aerated grit chambers to more than 10 min.