Research Centre for Natural Resources, Environment and Society (CERNAS), Portugal; Materials and Ceramic Engineering Department, CICECO, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
Research Centre for Natural Resources, Environment and Society (CERNAS), Portugal; Departamento de Ciências e Tecnologia (DCeT), Universidade Aberta, Lisboa, Portugal.
Waste Manag. 2021 Apr 15;125:293-302. doi: 10.1016/j.wasman.2021.02.055. Epub 2021 Mar 12.
The recovery of valuable materials from waste fits the principle of circular economy and sustainable use of resources, but contaminants in the waste are still a major obstacle. This works proposes a novel approach to recover high-purity phosphorus (P) and nitrogen (N) from digestate of municipal solid waste based on the combination of two independent membrane processes: electrodialytic (ED) process to extract P, and gas permeable membranes (GPM) for N extraction. A laboratory ED cell was adapted to accommodate a GPM. The length of waste compartment (10 cm; 15 cm), current intensity (50 mA; 75 mA) and operation time (9 days; 12 days) were the variables tested. 81% of P in the waste was successfully extracted to the anolyte when an electric current of 75 mA was applied for 9 days, and 74% of NH was extracted into an acid-trapping solution. The two purified nutrient solutions were subsequently used in the synthesis of a biofertilizer (secondary struvite) through precipitation, achieving an efficiency of 99.5%. The properties of the secondary struvite synthesized using N and P recovered from the waste were similar to secondary struvite formed using synthetic chemicals but the costs were higher due to the need to neutralize the acid-trapping solution, highlighting the need to further tune the process and make it economically more competitive. The high recycling rates of P and N achieved are encouraging and widen the possibility of replacing synthetic fertilizers, manufactured from finite sources, by secondary biofertilizers produced using nutrients extracted from wastes.
从废物中回收有价值的材料符合循环经济和资源可持续利用的原则，但废物中的污染物仍然是一个主要障碍。本研究提出了一种从城市固体废物消化物中回收高纯度磷（P）和氮（N）的新方法，该方法基于两种独立的膜过程的结合：电渗析（ED）过程提取 P，以及透气膜（GPM）提取 N。实验室 ED 电池经过改装以容纳 GPM。测试了废物室的长度（10cm；15cm）、电流强度（50mA；75mA）和操作时间（9 天；12 天）这三个变量。当施加 75mA 的电流 9 天时，废物中有 81%的 P 成功地被提取到阳极电解液中，74%的 NH 被提取到酸捕获溶液中。随后，将这两种纯化的营养溶液用于沉淀合成生物肥料（二次鸟粪石），效率达到 99.5%。使用从废物中回收的 N 和 P 合成的二次鸟粪石的性质与使用合成化学品形成的二次鸟粪石相似，但由于需要中和酸捕获溶液，成本更高，这突出表明需要进一步调整该工艺使其更具经济性竞争力。实现的 P 和 N 的高回收率令人鼓舞，并拓宽了用从废物中提取的营养物质生产的二次生物肥料替代由有限资源制造的合成肥料的可能性。
