重金属螯合剂TMT-15处理高含汞气田废水

选用重金属螯合剂TMT-15处理高含汞气田废水(COD=1 560 mg/L,SS=210 mg/L,pH=2.5~3.0,汞质量浓度为340 mg/L),考察了TMT-15投加量,废水pH,与氢氧化物、硫化物联用等因素对汞去除效果的影响,分析了TMT-15与汞的螯合产物的稳定性。实验结果表明:TMT-15能与汞强力螯合并沉淀,投加量低,pH适用范围广;絮凝剂聚合硫酸铝与TMT-15的联用可提高除汞效果,但作用有限;TMT-15与氢氧化物联用时的汞的去除效果提升显著,在氢氧化钠、三聚硫氰酸、汞元素的摩尔比为0.5:0.5:1和废水pH为3.0的条件下,汞去除率可达99.99%,剩余汞浓度低于GB 8978—1996中规定的汞排放浓度;螫合产物具有很高的热稳定性,且在较高浓度的酸碱环境中溶解率低,对环境造成二次污染的风险小。

Treatment of Gas Field Wastewater with High Mercury Concentration Using Heavy Metal Chelator TMT-15

The gas filed wastewater with high mercury concentration （COD=1 560 mg/L,SS=210 mg/L,pH=2.5-3.0,ρ（Hg）=340 mg/L）was treated using heavy metal chelator TMT-15. The factors affecting mercury removal were studied,such as TMT-15 dosage,wastewater pH,hydroxide,sulfide and so on,and the stability of the chelation product was analyzed. The experimental results show that：TMT-15 can chelate and precipitate with mercury under low dosage and wide pH range;The combination of flocculant PAS and TMT-15 has limited effect on mercury removal;When TMT-15 is used with hydroxide,the mercury removal rate is increased significantly;Under the conditions of mole ratio of sodium to trithiocyanuric acid to mercury 0.5∶0.5∶1 and wastewater pH 3.0,the mercury removal rate reaches 99.99%,and the residual mercury concentration is below the mercury emission standard of GB 8978-1996;The chelation product has high thermal stability and low dissolution rate in high-concentration acid/base environment,which indicates that it has low risk of secondary environmental pollution.