用工业废碱水处理反渗透法高含盐排放浓水

反渗透处理装置排放的浓水含盐量很高，如果不经处理直接排放势必对周围环境造成污染和水的浪费，氧化铝生产工艺废水中含有大量的碳酸钠、苛性碱等碱类物质，pH值达到13左右，回水量约2000m^3／h，用这些废水和反渗透浓水混合进行软化处理，降低浓水中的钙镁离子含量，并对难去除的硫酸盐进行稀释降低浓度，回用到蒸发循环水系统作为补充用水、氧化铝生产部分工艺用水、设备冷却用水，达到浓水回收再利用的目的。该方案实施后效果十分显著，回收反渗透浓水约60m^3／h，减少污水系统补充新水，降低生产用水费用约每年176万元。

TREATMENT OF RO DISCHARGING WATER AT HIGH SALINITY WITH SPENT ALKALINE LIQUOR

The wastewater from the production of aluminium oxide contains a great deal of sodium carbonate,sodium hydroxide etc. alkaline substances with pH as high as 14 and reflux water of 2000m^3/h; these wastewater is mixed with RO concentrated water for carrying out softening treatment to lower the content of calcium and magnesium ions in concentrated water; meanwhile, sulfate, which is difficult to be removed, is dilute to lower concentration, then it is reused to the cyclical water system for evaporation as make-up water, partial processing water for aluminium oxide production and cooling water for equipment, attaining the purpose of reuse of concentrated water. After implemented, the scheme showed very marked benefit.