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A novel approach for nutrients recovery from municipal waste as biofertilizers by combining electrodialytic and gas permeable membrane technologies
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Orientador(es)
Resumo(s)
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.
Descrição
Palavras-chave
Phosphorus Nitrogen Struvite Nutrient recycling Waste valorization Seawate