Study On Control Of RO Membrane Fouling For Regenerate Wastewater From Iron And Steel Works

Iron and steel works let off much circulate cooling wastewater everyday,it is worth to treat and reuse it as circulate cooling make-up water.Membrane fouling is one of big problem in the application of membrane technology. In order to keep the long-term and stable run effect of membrane parts, it's necessary to analyse the quality of wastewater, to make acceptable pretreatment technology, to find the best parameter.The control of RO membrane fouling for regenerate wastewater from iron and steel works were systematically studied in the paper.In this paper, the quality of wastewater was analyzed.Based on the results of water quality analysis, the wastewater has scaling tendency;suspended substance,oil,Fe,Mn were overproof;and organic matter in the water can cause microorganism pollute.The SF(sand filter)-GAC(granular activates carbon)-MF (microfiltration)-RO(reverse osmosis)system was adopted to treat the wastewater.The optimum dosing amount of PAC,HCl,NaClO were determined from the angle of decreasing suspended substance and colloid. The result showed that the optimum dosing amount of medicament which made the perfect coagulate, the average turbidity is 0.2NTU,silt density index (SDI) is less than 3, which could meet the requirements of RO feed. The dosage of PAC is 15mg/L;the dosage of NaClO is 6 mg/L.If continued dosing PAM, turbidness and SDI of the wasterwater were increasing,the reason of the phenomenon is colloid stabilization.So stopping dosing PAM was suggested.Through the variation of CODMn with the dosage of O3,the dosage of O3 was defined as 1.5mg/L.The writer made an overall observation on the effectiveness of O3-GAC process of removing colourity,CODMn,UV254,oil,Fe,Mn. The result showed that O3-GAC filters have high removal efficiency of such contaminant which could meet the requirements of RO feed. The remove rate of colourity is 70%; the remove rate of CODMn is 67%; the remove rate of oil is 87.5%; the remove rate of Fe2+ is 85.7%; the remove rate of Mn2+ is 62.5%. The strong oxidizing action of the O3 can broke the unsaturated bond, open benzene ring, transform macromolecule to micromolecule, then through the adsorption of the GAC to remove the pollutant.To test the dependability of adding scale inhibitor technology, the experiment of scale inhibitor was conducted.The result showed that RO membrane was scaling fast. It is proved that the scale inhibitor can not inhibit scale effectively.So it is necessary to change scale inhibitor. In the end,the special membrane cleaning method is presented.