纳滤膜在高盐废水零排放领域的分盐性能研究

摘要

煤化工高盐废水蒸发结晶的产品主要是NaCl和Na2SO4,通常100℃析出Na2SO4,50℃产出NaCl,二者共饱和时液相[Cl-]/[SO42-]分别为5.2和4.1,为提升分盐效率,应使进料[Cl-]/[SO42-]5.2或4.1,为此拟通过纳滤膜来实现这一目标.通过中试试验验证纳滤膜的分盐性能,结果表明:当进水[Cl-]/[SO42-]=1.2时,纳滤产水[Cl-]/[SO42-]=13.64.1,纳滤浓水[Cl-]/[SO42-]=0.35.2,SO42-截留率为90.3%,Cl-截留率为-7.2%;当进水[Cl-]/[SO42-]=3.0时,纳滤产水[Cl-]/[SO42-]=45.84.1,纳滤浓水[Cl-]/[SO42-]=0.85.2,SO42-截留率为92.2%,Cl-截留率为-4.5%.由此可见,采用纳滤膜进行初步分盐可以大大提升蒸发结晶的分盐效率.%The products from the evaporation and crystallization of high salinity wastewater in coal chemical indus?try are mainly NaCl and Na2SO4. Usually,Na2SO4 is precipitated at 100℃while NaCl produced at 50℃. When both of them are in the co?saturated state ,the liquid phase of [Cl-]/[SO42-]=5.2 and 4.1,respectively. In order to improve the efficiency of inorganic salt separation,the feeding materials should be [Cl-]/[SO42-]5.2 or4.1. It is proposed that the goal can be reached through the nano?filtration membrane. The salt separation performance of nano?filtration membranes is verified by pilot scale tests. The results show that when the influent is [Cl-]/[SO42-]=1.2,the nano?produced water is [Cl-]/[SO42-]=13.64.1,nano?produced concentrated water is [Cl-]/[SO42-]=0.35.2,SO42-interception rate 90.3,and Cl-interception rate-7.2%. When the influent is [Cl-]/[SO42-]=3.0,the nano?produced water is [Cl-]/[SO42-]=45.84.1,nano concentrated water is [Cl-]/[SO42-]=0.85.2,SO42-interception rate is 92.2%,and Cl-interception rate is-4.5%. Thus it can be seen that using nano?filtration membrane for prelimi?nary salt separation can greatly increase the salt separation efficiency of evaporation and crystallization.