石化行业高含盐废水的分盐零排放中试及应用

Treatment of High Salinity Wastewater to Achieve Zero Liquid Discharge in Petrochemical Industry

采用MCR+浓水RO+NF+DTRO/ED+蒸发结晶的工艺路线,对某石化行业高含盐废水进行分盐零排放中试。结果表明,ED浓水的含盐量在15%~25%之间,DTRO浓水的含盐量在15%~22%之间,两者在浓缩后的TDS方面相差不大,但DTRO产水水质和脱盐率明显高于ED。通过冷冻结晶法分离的硫酸钠结晶盐的品质高于热法分离,而热法分盐的优势是工艺简单、运行可靠性强、投资和运行成本低。系统经过长时间运行,设备稳定可靠,证实工艺路线合理,氯化钠、硫酸钠纯度均达到工业盐要求。

The process of zero hardness membrane chemical reactor( MCR) + reverse osmosis of concentrated water + nanofiltration + disc tube reverse osmosis( DTRO)/electro dialysis( ED) + evaporate and crystallize was applied to treat high salinity wastewater to achieve zero liquid discharge in petrochemical industry. The results showed that,the salt content in ED concentrated water was 15%-25%,and that in DTRO concentrated water was 15%-22%. There was negligible difference between ED and DTRO regarding the concentration of TDS,but the water quality and desalination rate of DTRO were significantly higher than that of ED. The quality of sodium sulfate separated by freezing crystallization was higher than that of thermal separation,although the thermal salt splitting was a simple and reliable operation,with low capital and operating cost. The process was stable and reliable in long-term operation. The product of sodium chloride and sodium sulfate was comparable to the purity of industrial salt.