微生物电解池从剩余污泥热碱水解液中回收鸟粪石

Struvite recovery from excess sludge with alkaline thermal hydrolysis using microbial electrolysis cell

通过鸟粪石的形式回收城市污水处理厂剩余污泥中的氮磷,不仅可减少对环境的污染,而且可以实现氮磷的资源化。利用微生物电解池(microbial electrolysis cell,MEC)开展了回收剩余污泥热碱水解液中鸟粪石的研究,实验结果表明,剩余污泥通过热碱水解促进了磷酸盐的释放,经MEC处理后可形成鸟粪石沉淀。扫描电镜-能谱分析(SEM-EDS)结果表明,阴极沉淀物为斜方晶,主要成分为N、O、P、Mg,符合鸟粪石的成分组成及晶体特征。双室MEC的鸟粪石生成速率远大于单室MEC的,双室MEC对磷酸盐的去除率最高可达77%,而单室MEC对磷酸盐去除率最高为56%。在双室MEC中,随着外加电压的升高,鸟粪石的生成速率增大,当外加电压为0.95 V时,鸟粪石生成速率为0.37 g/(m2·h);当外加电压为1.15 V时,鸟粪石生成速率为0.61 g/(m2·h)。微生物电解池为剩余污泥中鸟粪石的回收提供了一种新的处理方法。

Recovery of nitrogen and phosphate from the excess sludge from municipal wastewater treatment plants via struvite precipitation could not only reduce environmental pollution but also effectively utilize of the N and P resources. Here,struvite recovery from the excess sludge by alkaline thermal treatment was investigated using microbial electrolysis cell（ MEC） technology. The experimental results showed that the phosphate released from the excess sludge could be enhanced via alkaline thermal treatment. Struvite precipitation may have taken place in the MEC. The SEM-EDS analysis on the surface of the MEC cathode showed that the precipitate was composed of N,O,P and Mg with an orthorhombic structure,which was consistent with the characteristics of the struvite. The production rate of struvite in the dual-chamber MEC was higher than that in the single-chamber MEC. The maximum phosphate removal could reach 77% in the dual-chamber MEC,while it was only 56% in the single-chamber MEC. The production rate of struvite in the dual-chamber MEC,increased with an increase in the applied voltage. The production rate of struvite was 0. 37 g /（ m^2·h） at an applied voltage of 0. 95 V,and rose to 0. 61 g /（ m^2·h） at 1. 15 V. Our results demonstrated that the MEC could be a promising method for struvite recovery from the excess sludge.