Physicochemical and Microbial Quality of the Asa River, Ilorin, Southwestern Nigeria

Abstract

This study assessed the physicochemical and microbiological quality of water samples from a segment of the Asa River in Ilorin, Nigeria, over an eight-week period. Water samples were analysed using the multiple tube fermentation technique and spread plate method, with microbial identification performed via standard microbiological procedures. Physicochemical parameters included pH (7.47–8.95), temperature (22.9–28.2°C), biological oxygen demand (BOD) (6.40–9.10 mg/L), total suspended solids, total dissolved solids, dissolved oxygen, and total solids. Microbial analysis revealed total heterotrophic counts ranging from 2.70–7.25 × 104 cfu/mL, total coliform counts from 1.45–6.05 × 104 cfu/mL, and faecal coliform counts from 1.45–3.40 × 104 cfu/mL. Identified bacterial species included Streptococcus sp., Escherichia coli, Shigella sp., Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, and Vibrio cholerae. Antibiotic susceptibility tests against eight common antibiotics showed multiple resistance, particularly in Klebsiella pneumoniae. Fungal isolates included Aspergillus niger, Rhizopus stolonifer, Aspergillus fumigatus, and Penicillium sp. The presence of antibiotic-resistant microorganisms indicates significant contamination of the Asa River, posing a public health risk if used for domestic purposes.