BACTERIOLOGICAL CONTAMINATION OF WASTEWATER, VEGETABLES, AND ASSOCIATED HEALTH RISKS IN MAIDUGURI, NIGERIA
Ali Galadima , Ikusemoran Mayomi and Zainab Chellube
Volume 13 Issue 2
Abstract
This study evaluated the bacteriological quality of River Ngadda wastewater and its effects on the safety and chemical composition of vegetables irrigated with the water in Maiduguri, Nigeria. Wastewater samples were collected aseptically from three sections of the river (upper, middle, and lower courses) and analyzed for total coliforms and pathogenic bacteria using standard microbiological techniques. A controlled farm experiment was conducted in which spinach (Spinacia oleracea) and okra (Abelmoschus esculentus) were irrigated with either River Ngadda wastewater or clean borehole water. Harvested vegetables were analyzed for elemental composition using atomic absorption spectrophotometry. Results showed extremely high total coliform counts across all river sections (159 × 10³–260 × 10³ CFU/100 mL), exceeding World Health Organization guidelines for safe irrigation by several orders of magnitude. Pathogenic bacteria including Escherichia coli, Salmonella spp., Staphylococcus aureus, Bacillus spp., and Klebsiella spp. were detected, indicating widespread fecal contamination. Vegetables irrigated with wastewater exhibited higher microbial contamination and altered nutrient profiles compared to controls. Wastewater irrigation increased the accumulation of sodium, magnesium, chloride, and phosphate, with okra showing greater sensitivity to nutrient imbalance than spinach. Trace levels of heavy metals, including cadmium and chromium, were detected in wastewater-irrigated crops, though concentrations remained below international safety limits. The findings demonstrate that untreated River Ngadda wastewater is unsuitable for irrigating edible crops due to significant microbiological hazards and potential long-term chemical risks. The study highlights the need for wastewater treatment, improved waste management, safe irrigation practices, and continuous monitoring to protect public health and ensure food Keywords: Wastewater Irrigation, Microbial Contamination, Foodborne Pathogens, E. coli, Salmonella, Public health, Urban Agriculture.
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