Phytoremediation of laundry wastewater using Pistia stratiotes and recycling of spent plant biomass for sustainable biomethane production

Abstract

This study investigates the decontamination of laundry wastewater (LWW) using Pistia stratiotes via phytoremediation and recyclability of residual macrophyte biomass for enriched bio-CH4 production. Phytoremediation was performed using a hydroponic system. The optimum phytoremediation factors were LWW concentration = 79.4 %, plant density = 4 plants/reactor, and retention time = 12.9 days. This condition offered maximum removal efficiencies of 82.32 ± 3.59 %, 67.19 ± 2.90 %, and 70.34 ± 3.56 % for NH4+, COD, and PO43−, respectively. The residual P. stratiotes biomass (RPSB) was anaerobically co-digested with buffalo dung (BD) at 1:1 (w/w, wet basis) for enriched bio-CH4 production, achieving a maximum cumulative bio-CH4 yield of 696.84 ± 35.82 mL/g-VS. The modified Gompertz kinetic model fitted well to the anaerobic co-digestion experimental data with R2-value = 94.4 %. The integrated phytoremediation/co-digestion scheme succeeded in promoting social well-being through improved water quality, clean energy recovery, and benefiting the environment through carbon footprint emission reduction. These outputs achieved multiple targets of sustainable development goals.