resumo
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 NH4+ 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. (C) 2021 Elsevier Ltd. All rights reserved.
categoria
Engineering, Environmental; Environmental Sciences
autores
Oliveira, V; Dias-Ferreira, C; Gonzalez-Garcia, I; Labrincha, J; Horta, C; Garcia-Gonzalez, MC
nossos autores
João António Labrincha Baptista
Professor Catedrático
Verónica Oliveira
Estudante de doutoramentoagradecimentos
Veronica Oliveira has been funded through FCT Fundacao para a Ciencia e para a Tecnologia by POCH - Programa Operacional Capital Humano within ESF - European Social Fund and by Portuguese national funds from MCTES (SFRH/BD/115312/2016). This work was supported by projects 0340-SYMBIOSIS-3-E and 0745-SYMBIOSIS-II-3-E, co-funded by FEDER Fundo Europeu de Desenvolvimento Regional through Interreg V-A Espana-Portugal (POC-TEP) 2014-2020 and project PID2019-106148RR-C41 (REVAL 2.0). Isabel Gonzalez-Garcia was supported by a grant from the National Research Agency (AEI) training program of research staff under the grant number BES-2017-082327.