Physicochemical Analysis and Microbiological Assessment of Tannery Effluent Discharged from Tanneries around Nigeria’s Kano Industrial Estates

Aims: Research study on physicochemical analysis and microbiological assessment of tannery effluent discharged from tanneries around Nigeria’s Kano industrial estate was carried out.

Duration of Study: The study was conducted between September 2015 and December 2016.

Methodology: A total of 10 effluent samples were aseptically collected and analyzed by standard methods. Physicochemical parameters were analyzed. The bacteriological quality of the tannery effluents was analyzed by total aerobic mesophilic count and total coliform count techniques. The isolated bacteria were microscopically and biochemically characterized.

Results: The pH of the analyzed effluents ranged between 6.80 and 7.50 at the temperature range of 25°C to 38°C. The sulphide content ranged between 0.30 mg/l to 0.37 mg/l, with ammonium content ranging from 0.40 mg/l to 0.48 mg/l. The chromium content ranged between 30 mg/l to 83 mg/l. The potassium content ranged between 0.07 mg/l to 0.40 mg/l, with magnesium ranging from 0.40 mg/l to 6.35 mg/l. Phosphorus content ranged from 4.00 mg/l to 4.50 mg/l. The total aerobic mesophilic counts and total coliform counts recorded the presence of Bacillus sp. Pseudomonas sp., Proteus mirabilis, Escherichia coli, Klebsiella sp. and Streptococcus faecalis. The total aerobic counts ranged from 4.40 × 104 to 2.73 × 105 cfu/ml. Samples B, C and G were found to be within the standard given by Federal Environmental Protection Agency. The total coliform counts ranged from 1.46 × 105 to 1.26 × 106 cfu/ml, with highest coliform counts of 1.26 × 106 cfu/ml in sample A, which is relatively higher than the permissible value of the World Health Organization guideline limit for faecal coliform bacteria.

Conclusion: The physicochemical parameters analyzed showed varying conformity and divergence to the standards set by the national and international environmental regulatory bodies. The study showed that contaminants were within statutory limits, with few samples recording hazardous potentials. The effluents could pose little or no environmental risk when let into open waters, but presence of Escherichia coli in the effluent shows the possibility that there may be an outbreak of waterborne diseases soon within the study area.