Gao Ming, Wang Menglu, Wu Chuanfu, Wang Xiaona, Yang Yufei, Liu Shu, Shimaoka Takayuki, Wang Qunhui
Department of Environmental Science and Engineering, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing Key Laboratory on Resource-oriented Treatment of Industrial Pollutants 30 Xueyuan Road, Haidian District Beijing 100083 PR China
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences Beijing 100012 PR China.
RSC Adv. 2020 Jul 15;10(44):26397-26406. doi: 10.1039/d0ra03113e. eCollection 2020 Jul 9.
Municipal solid waste incineration fly ash (referred to as the fly ash) presents an important environmental problem in China today, but strategies for its treatment have yet to be widely studied and implemented. The currently available methods for the dechlorination of fly ash are not sufficient, given the amounts of fly ash produced each year. To increase the reuse fraction of fly ash as raw material for cement production, we propose an improved dechlorination method. Specifically, fly ash was leached with the hydrolysate of municipal solid waste leachate (HMSWL) to remove the water-insoluble chlorine. Three-step HMSWL leaching removed 94.3% of the total chlorine in fly ash, much more than the 82.7% that was removed through three-step ultrapure water (UW) leaching. X-ray diffraction indicated that three-step UW leaching could remove Cl mainly in the forms of KCl, NaCl, CaClOH and AlOCl, whereas three-step HMSWL leaching could further remove more water-insoluble Cl in the forms of AlOCl. In addition, the experimental results further suggested that the low pH of HMSWL (4.9) contributed little to the water-insoluble Cl removal, whereas the displacement of organic acid radicals (especially by the butyrate radical) was the major cause of water-insoluble Cl removal. Therefore, HMSWL rich in butyrate radical could be an ideal water substitute for fly ash dechlorination.
城市固体废弃物焚烧飞灰（以下简称飞灰）是当前中国面临的一个重要环境问题，但其处理策略尚未得到广泛研究和实施。鉴于每年产生的飞灰量，现有的飞灰脱氯方法并不充分。为了提高飞灰作为水泥生产原料的再利用比例，我们提出了一种改进的脱氯方法。具体而言，用城市固体废弃物渗滤液水解产物（HMSWL）对飞灰进行浸出，以去除水不溶性氯。三步HMSWL浸出法去除了飞灰中94.3%的总氯，远高于三步超纯水（UW）浸出法去除的82.7%。X射线衍射表明，三步UW浸出法主要去除以KCl、NaCl、CaClOH和AlOCl形式存在的Cl，而三步HMSWL浸出法能进一步去除更多以AlOCl形式存在的水不溶性Cl。此外，实验结果还表明，HMSWL的低pH值（4.9）对水不溶性Cl的去除贡献不大，而有机酸根（尤其是丁酸根）的置换是水不溶性Cl去除的主要原因。因此，富含丁酸根的HMSWL可能是飞灰脱氯的理想水替代物。
