Abstract:

Leachate nanofiltration concentrate is still a concerning issue to be addressed in the municipal solid waste field. A close-loop hybrid process based on tight ultrafiltration membrane and gypsum crystallization technologies is promising in the treatment of leachate nanofiltration concentrate, while the derived gypsum sludge requires reasonable disposal or resource utilization. In this study, gypsum whisker was prepared by atmospheric acidification method with derived gypsum sludge as raw material. The effects of HCl concentration, reactant concentration, temperature and reaction time on gypsum whisker products were investigated by means of uniform design experiment and single factor experiment. The results showed that the optimal reaction conditions for preparing gypsum whisker were as follows: HCl concentration of 7mol/L, reactant concentration of 0.09g/mL, temperature of 55℃ and reaction time of 65min. The gypsum whisker product prepared under this condition had uniform appearance and a length-diameter ratio up to 137, which met the requirements of professional standard. The crystallization kinetics of gypsum whisker was further explored and the process accorded with the first-order kinetic equation. It was feasible to recycle the reaction substrate. This study provided technical reference for the resource utilization of derived gypsum sludge from a close-loop treatment of leachate nanofiltration concentrate.

Key words: leachate nanofiltration concentrate, gypsum sludge, atmospheric acidification method, gypsum whisker, crystallization kinetics

摘要：

垃圾渗滤液纳滤浓缩液处理是垃圾处理领域的一个难点和热点，基于致密超滤膜分离和石膏结晶技术的组合工艺可以实现其闭环处理，但运行过程中产生的石膏污泥需要合理的处置或资源利用。本文以闭环处理工艺的副产石膏污泥作为原料，采用常压酸化法制备石膏晶须。通过均匀设计实验与单因素实验结合的方法，考察了盐酸浓度、反应物浓度、温度、反应时间等因素对石膏晶须产品的影响。结果表明，石膏晶须制备的最佳反应条件为：盐酸浓度7mol/L、反应物浓度0.09g/mL、温度55℃、反应时间65min。在该条件下制备得到的石膏晶须产品外观均匀，长径比达到137，符合行业标准要求。还进一步探究了石膏晶须结晶动力学，其过程符合一级动力学关系式。反应底液循环利用具有可行性，为渗滤液纳滤浓缩液闭环处理的副产石膏资源利用提供了技术参考。

关键词: 渗滤液纳滤浓缩液, 石膏污泥, 常压酸化法, 石膏晶须, 结晶动力学