Experimental Study On NF Membrane Purifying Polluted Groundwater

Groundwater is important drinking water resources in city and town in our country.In recent years ,groundwater has been polluted more and more serious .What is more ,the pollution of groundwater appears complex and multi-component.Nanofiltration membrane purifying polluted groundwater was advanced in firsttime in China.To two different characters of ground water-shallow and deepgroundwater,with preperment of GAC,QS and MS ,NF membrane processes were studied.The reason of membrane fouling was analysed ,and effective cleaning ways were obtained too .In the end ,analysed the feasibility of the project.Real groundwater was the study object in the experiment.The groundwater was carried from Shanghai's suburbs:Changning,Baoshan ,Minhang and Songjiang.For shallow groundwater,GAC-NF can effectively remove turbidity.organic matter, inorganic matter and bacteria. GC/MS result made know that the number of organic matter in permeate had been decreased greatly.The membrane permeate can accord with the standard of drinking purifying water.The theory of GAC removing NOW was analysed ,and the biology stabilization of NF permeate was execellentFor deep groundwater ,QS-NF process and MS-NF process were studied mostly to find the removal to iron and manganese.As a result ,QS-NF process can remove iron effectively ,but the removal of manganese was not ideal .MS-NF process had a good removal to iron and manganese. Compare to variation of the membrane flux in three different pretrements ,found that the membrane flux of GAC-NF process descended most quickly.How operating press operating time and influent temperater to influence NF membrane was studied .With the help of solve-diffuse model ,explain operating press how to change membrane flux and separating character .The removal of ion reduced with the operating press increasing,and this opinion was reverse to others" conclusion.In experiment,membrane flux descended and the removal reduced with operating time increasing.Then the rules of operating time effecting membrane werepost displayed.How the influent temperater to influence membrane was analysised with solve-diffuse model and Arrhenius equation.Membrane fouling was the mostly reason to restrict the abroad application of membrane.Membrane inside and membrane flux salt concentration modle was gained. The modle of salt concentration polarization gene effecting membrane flux was constructed .Membrane flux changed with time in index.Scanning Electron Microscope to membrane face and FT-IR to membrane filthy analysing can concluded that the pollution of membrane was salt .mostly CaCO₃ and CaSO₄ · 2H₂O .Comparing to severals cleaning measures,found that acid and alkali by turns cleaning membrane can acquire ideal effect .The membrane character can resume about 90%.But it needs to exchange new membrane after a long using period.Integrating above experiment results,NF membrane purifying polluted groundwater is feasible in technology.Bases on accounting,building a 50m³/d NF membrane drinking water plant in groundwater as resource,total investment need about 357 million yuan ,and making water cost is about 58.5 yuan/t.It is far lower than market price of barrel of water whose price is about 317 yuan/t.