Design and evaluation of a scalable decentralised greywater treatment technology for reuse, towards climate and WASH resilient urban communities

Abstract

In the context of water scarcity and the post-COVID-19 pandemic, treating greywater from handwashing stations for reuse is essential and climate-resilient. This study evaluated sand and gravel filters with passive chlorination for greywater treatment. Greywater from a standalone handwashing station at Ejisu, Ghana, was collected as influent. Influent and filtrates were analysed for physico-chemical and microbial quality using American Public Health Association (APHA) and HACH protocols. Setups I and II, utilising sand media, effectively improved the physico-chemical quality and pathogen removal. Significant differences in filtrate quality were observed for BOD 5 , nitrate, turbidity, and COD removal (p < 0.05) across all treatment setups. Post-treatment analysis revealed phosphate concentrations in the filtrates of Setups I, II, and the control were all within regulatory limits. Filter run time was estimated as 44 days for Setup I, 45 days for Setup II, and 53 days for the control (Setup III). A paired-sample t-test indicated a significant difference in flow rates and filter run times across all treatment setups. Treated water from Setup I was the most suitable for handwashing, highlighting the effectiveness of low-cost greywater treatment technologies and the importance of media selection and system design. Its simplicity makes it ideal for schools, healthcare facilities, informal settlements, and during WASH emergencies. To scale-up the technology, modular designs, locally sourced materials, and community training for operation and maintenance should be prioritised. • The study designed and appraised three filters for greywater treatment. • Setups I and II had roughing filters and sand, and setup III had gravel at different depths. • Filtrate from setups I and II had better physico-chemical and microbial quality. • Significant differences were observed for BOD 5 , nitrate, turbidity, and COD removal. • Filtrate quality from setup I was most suitable for handwashing.