Environmental sustainability of municipal wastewater treatment through struvite precipitation: Influence of operational parameters

The environmental sustainability of wastewater treatment through phosphate (P) and ammonia (N) chemical precipitation (struvite) was examined using the life cycle assessment methodology. Thermally activated (calcined) cryptocrystalline magnesite used towards struvite formation four process parameters (contact time, dosage, initial pH temperature) were studied. Raising wastewater’s temperature to promote stripping found be environmentally unsound. Magnesite dosage contact time identified as hotspots, but not pH. In terms relevance, when ReCiPe 2016 impact method, human health damage category mostly affected, followed by resource availability, while ecosystems affected a much lesser extent. Environmental impacts grossly attributed South Africa’s fossil fuel-dependent energy mix, suggesting that renewable could largely improve system’s performance. optimal conditions, from perspective, 0.2 g L?1 feed 10 min mixing, at ambient (total footprint 60.9 ?Pt per treated L wastewater). To N removal efficacy, which is desirable in real-world applications, higher dosages mixing durations are required, albeit expense (e.g. 180 16 sharply rises 1.87 mPt L?1). net approach revealed avoided on midpoint categories freshwater marine eutrophication outweigh corresponding process. Results suggest low act fast, efficient, friendly pre-treatment step practically remove P reduce wastewater. On other hand, with durations, promising secondary method an overall footprint. Overall, results complement existing body knowledge techno-economic performance such systems provide insight decision- policy-makers sustainably scale up process, village- or industrial-level, rural Africa, Lesotho, further afield.