兰炭废水全过程零排放处理技术与应用

Zero discharge treatment technology for semi-coking wastewater and application

为解决兰炭废水处理难度大、废水中毒性污染物脱除率低、处理费用高等问题,迫切需要开发低成本、高稳定性全流程零排放处理技术。通过预处理除油去除废水中油类,强化脱酚蒸氨处理实现高效酚氨资源的回收,处理出水COD稳定达到≤6000 mg/L、氨氮达到50~100 mg/L。通过强化生化处理技术,废水中的COD、氨氮、总氰可稳定达到120~150 mg/L、5 mg/L、0.2 mg/L以下。采用高效臭氧催化氧化+MBR处理工艺,处理出水COD可稳定达到≤40 mg/L。强化脱盐预处理、多级别梯度脱盐及分盐处理集成,实现废水产水率≥90%。浓水经过纳滤分盐,纳滤淡水经过浓缩进行双极膜电渗析处理,实现10%~15%酸溶液、碱溶液的回收。纳滤浓水通过短程复分解与结晶处理工艺,在加入碳酸氢铵的条件下,制取高品质的硫酸铵(氮含量≥21%)和碳酸钠(纯度约97%)盐品,高效回收废水中有价资源,真正实现废水低成本零排放处理。

There exist problems in treating with semi-coking wastewater,such as difficult to treat,low removal rate of toxic pollutants in wastewater,and high treatment cost.It is necessary to develop treatment technologies with low cost,high stability and whole process zero emission.Oil substances in wastewater are removed by pretreatment,and the high-efficiency recovery of phenol-ammonia resource is realized through an enhanced phenol-removing and ammonia-evaporating treatment.The contents of COD and ammoniacal nitrogen in the treated effluent are less than 6000 mg·L^(-1)and 50-100 mg·L^(-1),respectively.Through strengthening the biochemical treatment technology,the contents of COD,ammoniacal nitrogen and total cyanide in wastewater can reach below 120-150 mg·L^(-1),5 mg·L^(-1)and 0.2 mg·L^(-1),respectively.The content of COD in the treated effluent can stably be less than 40 mg·L^(-1)after using high-efficient ozone catalytic oxidation+MBR process.Enhanced desalination pretreatment,multi-grade gradient desalination and salt splitting treatment are integrated to realize a water yield of more than 90%from wastewater.About 10%-15%of acid solution and alkali solution is recovered after the concentrated water has been separated by nanofiltration,and the fresh water has been concentrated by bipolar membrane electrodialysis.High-quality ammonium sulfate(nitrogen content≥21%)and sodium carbonate(a purity of about 97%)salts are obtained from concentrated nanofiltration water by short-range double decomposition and crystallization processes with the addition of ammonium bicarbonate.High-efficient recovery of valuable resources in wastewater achieves low-cost zero-discharge wastewater treatment.