Biodegradation of abattoir wastewater using indigenous bacterial strains

Abstract

An abattoir is an approved and authorised area meant for the slaughtering, processing and preservation of meat products for human use. Bioremediation potentials of indigenous bacterial strains from abattoir wastewater located in Minna metropolis, Nigeria were examined. Wastewater was collected and serially diluted, plated on nutrient agar for bacterial isolation using pour plate isolation method. The isolates were identified based on their cultural, biochemical, and molecular characteristics. The isolates identified were Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus and Staphylococcus aureus. The isolates were cultured on Mineral Salt media for 7 days and were screened for their biodegradation potential using UV-VIS spectrophotometric analysis. Results revealed 94%, 90%, 82%, 75%, and 73% biodegradation rates for Bacillus subtilis, Pseudomonas aeruginosa, Bacillus cereus, Escherichia coli, Staphylococcus aureus and Bacillus subtilis respectively. Bacillus subtilis and Pseudomonas aeruginosa were used singly and in combination for bioremediation of the wastewater. Changes in the physicochemical parameters were evaluated. Bacillus subtilis exhibited great potential in reduction of most parameters after 28 days of inoculation and treatment. The BOD of sterile wastewater was reduced from 259.00 mg/L to 75.12 mg/L, COD 173.08 mg/L to 64.59 mg/L, nitrate 16.09 mg/L to 5.39 mg/L, phosphate 1.73 mg/L to 0.61 mg/L, ammonia 4.86 mg/L to 2.43 mg/L and pH 6.41 to 5.22. Pseudomonas aeruginosa reduced BOD from 259.00 mg/L to 97.12 mg/L, COD 173.08 mg/L to 71.79 mg/L, nitrate 16.09 mg/L to 5.13 mg/L, phosphate 1.73 mg/L to 0.37 mg/L, ammonia 4.86 mg/L to 1.44 mg/L; pH reduced from 6.41 to 5.64. The combination efficacy was observed in the reduction of BOD from 259.00 mg/L to 58.82 mg/L, COD 173.08 mg/L to 56.39 mg/L, nitrate 16.09 mg/L to 2.49 mg/L, phosphate 1.73 mg/L to 0.24 mg/L ammonia 4.86 mg/L to 0.84 mg/L and pH 6.41 to 5.64. The results revealed significant difference (p) amongst the parameters during the period of biodegradation. The results indicated that Bacillus subtilis and Pseudomonas aeruginosa are promising microorganisms for industrial applications such as bioremediation of abattoir wastewater.