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article · Microbiology Research International

Comparative effects of selected indigenous bacterial treatments on the physicochemical characteristics of abattoir wastewater in Port Harcourt, Nigeria

In plain language

Untreated abattoir wastewater presents considerable environmental and health risks due to elevated organic matter, nutrients, and microbial contamination. An evaluation of wastewater from abattoirs in Port Harcourt, Nigeria, assessed the potential of indigenous bacterial strains to improve water quality over a 21-day laboratory period. Fifteen bacterial isolates spanning ten probable taxa were identified, including Bacillus, Pseudomonas, and various enteric bacteria. Among tested single strains, Pseudomonas sp. displayed the highest growth response and achieved the greatest reduction in total dissolved solids at 26.7%. A mixed consortium of probable enteric bacteria delivered the highest reductions in electrical conductivity, biochemical oxygen demand, nitrate, and phosphate. However, because this consortium contained probable pathogens such as Escherichia coli, Klebsiella sp., and Salmonella sp., its real-world environmental application is restricted, highlighting Pseudomonas sp. and Bacillus sp. as safer candidates for further treatment research.

Key takeaways

  • Pseudomonas sp. achieved the highest reduction in total dissolved solids at 26.7% over 21 days.
  • A bacterial consortium produced the greatest decreases in nitrate, phosphate, biochemical oxygen demand, and electrical conductivity.
  • The tested bacterial consortium contained probable pathogens, restricting its suitability for environmental deployment.
  • Pseudomonas sp. and Bacillus sp. were identified as the most viable indigenous isolates for continuing wastewater treatment investigations.

Why it matters

Abattoir effluent contains hazardous nutrients, dissolved solids, and microbial pathogens that can contaminate local water systems. By testing local bacteria to break down these contaminants, this work reveals how native microbes alter wastewater chemistry while demonstrating why treatment performance must be balanced against the safety risks of deploying potentially pathogenic bacterial strains.

Commercialisation angle

This research is at an early laboratory stage, focused on biological wastewater treatment options for abattoir operators and municipal effluent managers. While showing that indigenous Pseudomonas sp. and Bacillus sp. can reduce specific contaminants, practical use requires developing non-pathogenic formulations and scaling tests beyond laboratory conditions before commercial deployment can be considered.

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Abstract

Abattoir wastewater contains high concentrations of organic matter, nutrients, dissolved solids, and diverse microorganisms that may pose environmental and public health risks when discharged without adequate treatment. This study evaluated the bacteriological characteristics of abattoir wastewater and comparatively assessed the effects of selected indigenous bacterial isolates on its physicochemical characteristics. Wastewater samples were collected from selected abattoirs in Port Harcourt, Rivers State, Nigeria. Standard microbiological techniques were used for bacterial enumeration, isolation, characterization, and identification. The growth potential of the bacterial isolates in wastewater-supplemented mineral salt medium was assessed using optical density measurements. Selected Pseudomonas sp. and Bacillus sp. isolates, together with a separately formulated consortium of probable enteric bacteria, were evaluated under laboratory conditions for 21 days, with physicochemical parameters monitored at seven-day intervals. Mean total heterotrophic bacterial counts ranged from 6.33 × 106 to 1.60 × 107 CFU/mL, total coliform counts from 2.63 × 105 to 5.00 × 105 CFU/mL, and total faecal coliform counts from 5.00 × 103 to 1.73 × 104 CFU/mL. Total Pseudomonas counts ranged from 0 to 1.37 × 104 CFU/mL, Salmonella-Shigella counts from 8.33 × 103 to 2.80 × 104 CFU/mL, and total staphylococcal counts from 1.00 × 103 to 1.33 × 103 CFU/mL. Fifteen bacterial isolates representing ten probable bacterial taxa, including Bacillus, Pseudomonas, Escherichia, Klebsiella, Salmonella, Shigella, Staphylococcus, Serratia, Chromobacterium, and Micrococcus, were recovered. Pseudomonas sp. exhibited the highest growth response in the mineral salt medium (OD550 = 1.678). After 21 days of treatment, the consortium produced the greatest reductions in electrical conductivity, biochemical oxygen demand, nitrate, and phosphate, with reductions of 2.9%, 5.4%, 19.7%, and 31.5%, respectively, whereas Pseudomonas sp. produced the greatest reduction in total dissolved solids (26.7%). Temperature remained relatively stable throughout the treatment period, whereas pH showed a moderate increase. The findings demonstrate differential effects of the selected bacterial treatments on the physicochemical characteristics of abattoir wastewater. Although the consortium produced greater reductions in several parameters, its inclusion of probable Escherichia coli, Klebsiella sp., and Salmonella sp. limits its suitability for environmental application. The study highlights the potential of appropriately characterized indigenous bacterial isolates, particularly Pseudomonas sp. and Bacillus sp., for further laboratory-scale investigation of abattoir wastewater treatment and emphasizes the need to evaluate microbiological safety alongside treatment performance.

Research topics

  • Fecal contamination and water quality
  • Water Quality and Pollution Assessment
  • Microbial Community Ecology and Physiology

Sustainable Development Goals

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DOI: 10.5281/zenodo.22640599

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