Low-cost multi-stage filtration enhanced by coagulation-flocculation in upflow gravel filtration

Drinking Water Engineering and Science

J. T.Visscher¹  L. C.Rietveld¹  L. D.Sánchez¹  L. M.Marin¹ 

DOI  :  10.5194/dwes-5-73-2012

学科分类：工程和技术（综合）

来源: Copernicus Publications

【 摘 要 】

This paper assesses the operational and design aspects of coagulation andflocculation in upflow gravel filters (CF-UGF) in a multi-stage filtration(MSF) plant. This study shows that CF-UGF units improve the performance ofMSF considerably, when the system operates with turbidity above 30 NTU. Itstrongly reduces the load of particulate material before the water enters inthe slow sand filters (SSF) and therewith avoids short filter runs andprevents early interruption in SSF operations. The removal efficiency ofturbidity in the CF-UGF with coagulant was between 85 and 96%, whereasthe average efficiency without coagulant dosing was 46% (range:21–76%). Operating with coagulant also improves the removal efficiencyfor total coliforms, E-coli and HPC. No reduction was observed in the microbialactivity of the SSF, no obstruction of the SSF bed was demonstrated and SSFruns were maintained between 50 and 70 days for a maximum head loss of 0.70 m.The most important advantage is the flexibility of the system to operatewith and without coagulant according to the influent turbidity. It was onlynecessary for 20% of the time to operate with the coagulant. The CF-UGFunit represented 7% of total construction costs and the O&M cost forthe use of coagulant represented only 0.3%.

【 授权许可】

Unknown