焦化尾水资源化回用集成工艺中试

A pilot test of integrated process for resource reuse of coking tailwater

为实现焦化尾水的资源化回用,开发了以预处理、压力-电驱动膜组合及双极膜电渗析技术为核心的集成工艺,并进行了中试研究。集成工艺中,化学软化和臭氧-双氧水复合氧化工艺用于去除原水中的硬度和反渗透浓水中的难降解有机物,纳滤工艺完成了一价离子与高价离子的分离,电渗析和双极膜电渗析工艺实现了焦化尾水的近零排放和酸碱资源再生。化学软化工艺对原水的硬度去除率可达64.2%;臭氧-双氧水复合氧化工艺对反渗透浓水的COD去除率可达35.0%;纳滤工艺的脱盐率可达30.2%,对氯离子、硫酸根、硬度和TOC去除率分别可达-6.8%、97.3%、78.4%和87.4%;双极膜电渗析工艺可得浓度均为2 mol/L以上的酸和碱,能耗为4.0 kW·h/kg。该集成工艺的水回用率大于90%,酸碱可短程循环利用。

To achieve the resource reuse of coking tail water,an integrated process,incorporating pretreatment,pressure-and electrically-driven membrane coupled process,and bipolar membrane electrodialysis,has been devised and piloted.In the integrated process,chemical softening and ozone-hydrogen peroxide composite oxidation process removed hardness and organics.The nanofiltration process separated ions.The electrodialysis and bipolar membrane electrodialysis processes achieve near-zero discharge and acid-base recycling.The chemical softening process can remove up to 64.2%of the hardness in raw water.The ozone-hydrogen peroxide composite oxidation process can remove up to 35.0%of the COD in reverse osmosis concentrated water.The nanofiltration process can achieve a desalination rate of 30.2%,with removal rates of chlorine ions,sulfate radicals,hardness,and TOC of-6.8%,97.3%,78.4%,and 87.4%,respectively.The bipolar membrane electrodialysis process can obtain acids and bases with concentrations above 2 mol/L,with an energy consumption of 4.0 kW·h/kg.The water reuse rate of this integrated process exceeds 90%.Acids and bases can be recycled in a short-term cycle.