Abstract: 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^-]/[SO₄^2-]=5.2 and 4.1,respectively. In order to improve the efficiency of inorganic salt separation,the feeding materials should be[Cl^-]/[SO₄^2-]<<5.2 or >>4.1. 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^-]/[SO₄^2-]=1.2,the nano-produced water is[Cl^-]/[SO₄^2-]=13.6>>4.1,nano-produced concentrated water is[Cl^-]/[SO₄^2-]=0.3<< 5.2,SO₄^2- interception rate 90.3,and Cl^- interception rate -7.2%. When the influent is[Cl^-]/[SO₄^2-]=3.0,the nano-produced water is[Cl^-]/[SO₄^2-]=45.8>>4.1,nano concentrated water is[Cl^-]/[SO₄^2-]=0.8<<5.2,SO₄^2- 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.

Key words: high salt wastewater, zero liquid discharge, nano-filtration membrane, evaporation and crystallization, inorganic salt separation

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^-]/[SO₄^2-]分别为5.2和4.1，为提升分盐效率，应使进料[Cl^-]/[SO₄^2-]<<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^-]/[SO₄^2-]=1.2时，纳滤产水[Cl^-]/[SO₄^2-]=13.6>>4.1，纳滤浓水[Cl^-]/[SO₄^2-]=0.3<<5.2，SO₄^2-截留率为90.3%，Cl^-截留率为-7.2%；当进水[Cl^-]/[SO₄^2-]=3.0时，纳滤产水[Cl^-]/[SO₄^2-]=45.8>>4.1，纳滤浓水[Cl^-]/[SO₄^2-]=0.8<<5.2，SO₄^2-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。

关键词: 高盐废水, 零排放, 纳滤膜, 蒸发结晶, 分盐

CLC Number: 

• X703.1