Greywater characterization and handling practices among urban households in Ghana: the case of three communities in Kumasi Metropolis.

Greywater management in Ghana receives little or no attention although untreated greywater is associated with environmental and public health risks. This paper assesses greywater characteristics and handling practices among urban households in three selected communities in Kumasi, the second largest city of Ghana. The study involved in-depth surveys (interviews and observations) with 90 households, and collection of 18 greywater samples from nine greywater sources for laboratory analysis. Average greywater generation is 43.36 ± 17 litres per capita per day, equivalent to 36% of average water consumption. Greywater is untreated before disposal (≈99%), and disposal is mainly (89%) into drains and onto streets. Biochemical oxygen demand (BOD) and chemical oxygen demand (COD) levels are high but give very low BOD/COD ratios (0.20 ± 0.07) indicating a very low biodegradability potential. Nutrient levels are high: 12 times (P) and 30 times (N) in excess of standard discharge limits. Other contaminants detected are heavy metals (Fe, Pb, Zn and Cd), microbes (total coliforms, Escherichia coli and Salmonella spp.), and organic micropollutants - benzalkonium chloride, parabens (methyl and propyl), sodium benzoate and hypochlorite - and details of the levels are discussed in the paper. Greywater reuse could be useful for biomass production, but it also presents a challenge and threat to natural biological processes and water sources.