Research On Short-flow UF Water Purification Technology And Application In Design Of Water Plants

Currently,ultrafiltration membrane(UF)technology as the core of the third generation of water purification technology,has been increasingly widely used in the field of municipal water purification,in which submerged External-Pressure UF is most widely used.Generally,submerged UF includes long process and short process forms.At present,most of the UF water plants process in the form of a long process which is based on purely alternative sand filtration,very little short process applications.We need some research on short process UF technology in order to test the purification effect,applicability,economic and other aspects.In this paper,a upgrading project about a surface water plant in North China for the study,proposed UF process through analysis of the raw water quality and comparison of the different treatment processes,optimize the parameters through research on the long and short forms.The research provides a strong support for the feasibility and economy of short-flow UF applications in North China.The raw water flows from Yellow River through the reservoir with the characteristics of low temperature and turbidity in winter,high levels of alga and organics in the summer and fall.The existing conventional process has been difficult to deal with,Along with the growing raw water pollution and the improving of drinking water health standards,the emergency on water quality occurs occasionally.For raw water characteristics,proposed O3-GAC and UF upgrade program,after the comprehensive comparison,we choosed the UF program which has the features of lower investment,better treatment effect and lower energy consumption.With respect to feasibility,the test showes that submerged UF system has a good turbidity removal from turbidity,the guaranteed rate of turbidity ? 0.1 NTU is up to 100%.With submerged UF,the efficiency of algae and microbial removal is very good,however,the limited removal of organics and aluminum,the highest removal rate of CODMn is 39.12%,the lowest was 13.82%.Short and long process UF has almost the same removal of turbidity,algae and microorganisms,but they are all significantly better than conventional treatment process.In terms of removal of organic matter and metal ions,UF has no obvious advantage for conventional treatment processes.With respect to operation,the suitable emptied cycle is 5 h,the suitable dosage of coagulant is 6~10 mg/L,the suitable flux is 30 and 35 L/(m2·h)in North China for short-flow UF system.The combination of NaCl O\NaOH\HCl can recover the flux of membrane with the rate above 97%.With respect to economy,the integrated power consumption is 0.089~0.0161 kWh/m3,the coagulant cost is 0.0356~0.0396 Yuan/m3,the direct operating cost is 0.156~0.188 Yuan/m3,the retrieve rate of water is up to 89.98%~94.32%,while the flux is between 25 and 45 L/(m2·h).