HE Zhong, WANG Zhi-liang, YANG Shao-gui, SUN Cheng
After having been pretreated in turn with coagulation-sedimentation, sand filter and granular activated carbon (GAC), the water of Yangtse River was treated with nanofiltration(NF) and reverse osmosis(RO), respectively. The results indicate that the pretreatments are very important for later treatment reliability since they can remove most turbidity and some pollutants. Under the optimum pressure 0.4 MPa of NF which has been determined in pilot study, the water production quantity and the recovery rate are 250 L/h and 24%, respectively, the removal ratio of SO42-, Cl-, NO3- and total hardness is 91.7%, 85.4%, 85.2% and 89.3%, respectively. Concentrated water reflux can achieve both high recovery rate and removal rate. Additionally, both RO and NF can remove 95.7% of organic contaminants (benzene, trichloroethylene, ethylbenzene, m-xylene, chlorobenzene, nitrobenzene) and also can greatly control disinfection by-products (DBPs) with most elimination rate over 63.7%. Compared with RO, the operation cost of NF is low, and the effluent of NF can be used as drinking water as it contains favorable mineral substances.
