A systematic literature review on potential of ablution greywater reuse: current insights, challenges, and future prospects

An astounding 3.6 million mosques worldwide utilize 22.5 million \({\text{m}}^{3}\) of water for ablution. Treating and recycling ablution greywater (AGW) conserves significant water crucial for water-scarce regions. AGW recycling is extensively studied in the Muslim world but a comprehensive systematic literature review (SLR) synthesizing their outcomes is lacking. This study provides overviews and discussion on the actual status, challenges, and prospects of AGW reuse. This study presents an SLR on AGW reuse, analysing 1085 papers from 2000 to 2024, with 34 articles meeting inclusion criteria. Examined for quantity, quality, AGW characteristics, and recycling methods. AGW recycling has risen in the past decade due to water scarcity. Despite fewer pollutants, AGW still requires specific, less intensive treatment. AGW meets various countries’ guidelines, with pH, TDS, BOD, COD, E.C, E. coli, and faecal coliforms levels at 7.35, 525.8 mg/litre, 78.87 mg/litre, 122.4 mg/litre, 909.57 μS \({\text{cm}}^{-1}\), 110 CFU/100 ml, and 670.96 MPN/100 ml, respectively. Further research is necessary to address technology, finance, regulations, and community acceptance for the versatile application of greywater recycling. This research highlights a gap in determining cost-effective AGW recycling, focussing on treatment methods, cost efficiency, social acceptance, and environmental concerns, offering researchers an opportunity to explore optimal solutions.