Process Studies Of Membranes Technique In Treating High-Concentration Brine

Nanofiltration is one of a new membrane separation technologies,its characteristics was between Ultrafiltration and Reverse Osmosis.The molecular weight retention (MWCO) is between100and1000,with characteristics of a selective permeability,reject of divalent ions and through monovalent ions. It is a very wide range of applications, including watertreatment, petrochemical, food processing and other fields.Nanofiltration process of dealing with a relatively high concentration of brine compared with several denitrification methods exited, such as freezing process, barium chloride process, has advantage in environmental protection, green and security et.The subject using the saline that the concentration was self-made, selected the membranes type of HNF40-4040, HNF90-4040from U.S.Hydrancutics company for researching the denitrification process of nanofiltration membrane performance.Two types of membrane text in single-factor,and divided the operating factors that effect membrane separation performance into three kinds,inCluding operating pressure, test temperature, feed concentration.and then choose different conditions for experiment.The results show that the feed concentration,operating pressure and temperature have different effects on the membrane flux, which increase the operating pressure or elevated temperature experiments, the flux will increase; and the higher feed concentration, the more flux small. Significant effect on the rejection factor is the pressure,raise the pressure, retention would imporve; increased feed concentration, the rejection decreased, raising the temperature, rejection rate was fluctuated, slightly deCline.The subject using brine from Huai an salt mine, compared denitrification effect between NF40-4040and NF90-4040membrane. Original water through the nanofiltration membrane NF40-4040treatment, in0.8MPa,1.0MPa,1.2MPa,1.4MPa,1.6MPa pressure conditions, the SO42-concentrations were0.4834%,0.4357%,0.3571%,0.3031%,0.2518%, NF90-4040membrane under the same conditions was0.2301%,0.2023%,0.1482%,0.1045%,0.0948%of the SO42-concentration. Experiment results show that if the pressure conditions in more thanl.0MPa,the water producted both by NF40-4040NF90-4040membrane can be reached denitrification purposes; on the same pressure conditions, NF40-4040membrane chloride rejection rate is lower than NF90-4040, and with more high flux,so,it is more suitable for process requirements.The subject investigate the relationship between the membrane fouling and the membrane flux, results of experiment show that the use of water for cleaning the membrane flux can be restored within a short time, but increase in operating time, its basic Cleaning does not work; use of Cleaning chemicals make the membrane flux is almost completely restored.Through experimental results, the NF40-4040nanofiltration membrane was final selection for designingd process of treat high concentrations of brine,and find the best operating parameters, defined the fouling cycle of membrane.