Experimental investigation of the efficiency of coffee husks in a bioretention model for stormwater treatment

ABSTRACT Urbanization exacerbates stormwater treatment and management challenges due to increased runoff volume and pollutant loads. Contrary to conventional management infrastructure, bioretention uses filter media and some organic additives for removing stormwater pollutants. Coffee husk is a promising and versatile by-product whose performance has not been investigated. This study experimentally investigates the utilization of coffee husks for stormwater pretreatment. The potentiality was investigated in a bioretention model consisting of four columns: J (control with typical sand filter), M, N, and P (with different depths of coffee husks). The physical, chemical, and biological parameters, such as total suspended solids, total coliforms, faecal coliforms, chlorides, sulphates, turbidity, and colour were evaluated in raw and treated stormwater samples at intervals 0, 5 10, 20, and 30 days of bioretention treatment. The results showed that all columns had diverse efficiencies, with Column P showing the most notable improvement to meet the NEMA discharge limits. The Column P, which had the highest depth of coffee husks, exhibited 82.78% efficiency in enhancing stormwater quality for all the parameters, except colour. The results indicated that its design and filter media configuration is most efficient and can be used as a sustainable approach in stormwater pretreatment and management.