BIONATURE

This study evaluated the biodegradation potential of surfactants in selected commercial liquid detergents using water samples and a river water die-away test. Six liquid detergents (LB Wash ‘N’ Wax, Classic Hand Wash, Morning Fresh, Mama Lemon, Newday Fresh and Lily Fresh) and sodium dodecyl sulphate (SDS) standard were examined. Total viable heterotrophic bacterial counts, detergent-utilising bacterial counts, bacterial isolates, pH, chemical oxygen demand (COD), sulphate, nitrate and percentage surfactant remaining were assessed for 28 days. The total viable heterotrophic bacterial counts recorded for River Niger water and tap water were 1.57 x 10^6 and 3.4 x 10^5 cfu/ml, respectively. Detergent-utilising bacterial counts were higher in river water than in tap water, ranging from 3.0 x 10^4 to 1.04 x 10^6 cfu/ml and from 5.0 x 10^2 to 9.3 x 10^3 cfu/ml, respectively. The corresponding percentages were 1.9-66.2% and 0.1-2.7%. The bacterial genera associated with detergent utilisation included Escherichia, Pseudomonas, Staphylococcus, Bacillus, Salmonella, Flavobacterium, Enterobacter and Citrobacter, with Pseudomonas spp. showing the highest frequency of isolation (28.57%). During the die-away test, pH generally increased, whereas COD, sulphate, nitrate and surfactant concentrations decreased. By day 28, COD values declined to 25-45 mg/L, and surfactant remaining ranged from 10.00 to 50.00%. Total viable counts generally increased up to day 20 before declining. These findings indicate variable biodegradation among the detergent formulations and suggest that indigenous river water bacteria contributed to detergent constituent utilisation under the test conditions.