Evaluation of Biodegradability and Environmental Fate of Synthetic Detergents in Receiving Waters in Kano State

The widespread use of synthetic laundry detergents in households and commercial laundries has contributed to the contamination of receiving water bodies with surfactants, phosphates, and associated auxiliary compounds. This study evaluates the biodegradability and environmental fate of surfactants from synthetic detergents in selected water bodies in Kano State, North West Nigeria. Effluent samples were collected from residential drainage points, informal laundry sites along river banks, and receiving streams over a six-week period. Linear alkylbenzene sulphonate, the primary anionic surfactant in most Nigerian laundry products, was quantified using the methylene blue active substances spectrophotometric method. Phosphate levels were determined by the ascorbic acid method. Biodegradation experiments were conducted in laboratory microcosms using river water inocula to simulate in-situ degradation under aerobic conditions, monitoring surfactant disappearance over 28 days. Results show that linear alkylbenzene sulphonate biodegrades by approximately 78 percent under aerobic conditions within 28 days, but natural attenuation in receiving rivers is inhibited during dry season by reduced flow and dissolved oxygen. Phosphate levels at several sampling points indicated hypereutrophic conditions during the dry season. The study recommends the promotion of phosphate-free and biodegradable detergent formulations, consumer education, and regulation of detergent phosphate content by the Standards Organisation of Nigeria. Keywords: synthetic detergents, surfactants, biodegradability, Kano State, water pollution