School of Environmental and Chemical Engineering, Shanghai University, No. 99, Shangda Road, Shanghai 200444, PR China; Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
Sci Total Environ. 2018 Jan 1;610-611:137-146. doi: 10.1016/j.scitotenv.2017.08.038. Epub 2017 Aug 10.
Landfill leachate contains substances that can be potentially recovered as valuable resources. In this study, magnesium in a landfill leachate was recovered as struvite with calcium pretreatment; meanwhile, the leachate volume was reduced by using a submerged forward osmosis (FO) process, thereby enabling significant reduction of further treatment footprint and cost. Without pretreatment, calcium exhibited strong competition for phosphate with magnesium. The pretreatment with a Ca: CO molar ratio of 1:1.4 achieved a relatively low loss rate of Mg (24.1±2.0%) and high Ca removal efficiency (89.5±1.7%). During struvite recovery, 98.6±0.1% of magnesium could be recovered with a significantly lower residual PO-P concentration (<25mgL) under the condition of (Mg+Ca): P molar ratio of 1:1.5 and pH9.5. The obtained struvite had a similar crystal structure and composition (19.3% Mg and 29.8% P) to that of standard struvite. The FO process successfully recovered water from the leachate and reduced its volume by 37%. The configuration of calcium pretreatment - FO - struvite recovery was found to be the optimal arrangement in terms of FO performance. These results have demonstrated the feasibility of magnesium recovery from landfill leachate and the importance of the calcium pretreatment, and will encourage further efforts to assess the value and purity of struvite for commercial use and to develop new methods for resource recovery from leachate.
垃圾渗滤液中含有可回收利用的有价值资源物质。本研究采用钙预处理-淹没式正渗透（FO）工艺回收垃圾渗滤液中的镁，以鸟粪石的形式回收，同时减少渗滤液的体积，从而显著减少进一步处理的占地面积和成本。未经预处理时，钙与镁对磷酸盐具有很强的竞争。采用 Ca:CO 摩尔比为 1:1.4 的预处理方法，镁的损失率相对较低（24.1±2.0%），钙的去除效率较高（89.5±1.7%）。在回收鸟粪石的过程中，在（Mg+Ca）：P 摩尔比为 1:1.5 和 pH9.5 的条件下，可回收 98.6±0.1%的镁，且残余 PO-P 浓度显著降低（<25mgL）。得到的鸟粪石与标准鸟粪石具有相似的晶体结构和组成（19.3%Mg 和 29.8%P）。FO 过程成功地从渗滤液中回收了水，将其体积减少了 37%。钙预处理-FO-鸟粪石回收工艺在 FO 性能方面被证明是最佳的配置。这些结果表明从垃圾渗滤液中回收镁的可行性以及钙预处理的重要性，并将鼓励进一步努力评估鸟粪石的商业价值和纯度，以及开发从渗滤液中回收资源的新方法。
