African Journal of
Microbiology Research

  • Abbreviation: Afr. J. Microbiol. Res.
  • Language: English
  • ISSN: 1996-0808
  • DOI: 10.5897/AJMR
  • Start Year: 2007
  • Published Articles: 5114

Full Length Research Paper

Optimisation of biological wastewater treatment for yeast processing effluent using cultured bacteria: Application of response surface methodology

Manhokwe S.
  • Manhokwe S.
  • Department of Food Science and Nutrition, Midlands State University, P. Bag 9055, Gweru, Zimbabwe.
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Shoko S.
  • Shoko S.
  • Department of Applied Biosciences and Biotechnology, Midlands State University, P. Bag 9055, Gweru, Zimbabwe.
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Zvidzai C.
  • Zvidzai C.
  • Department of Biotechnology, Chinhoyi University of Technology, P. Bag 7724, Chinhoyi, Zimbabwe.
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  •  Received: 05 July 2019
  •  Accepted: 14 August 2019
  •  Published: 31 August 2019


In the present study, the interactive effects of temperature and cultured bacteria on the performance of a biological treatment system of wastewater from a local yeast producing plant were investigated. The main objective of this study was to optimize the operating parameters that reduce organic load and colour. Biological treatment was conducted using a Central Composite Design (CCD) and optimised using Response Surface Methodology (RSM) on Design Expert 7 software. Two dependent variables namely, Chemical Oxygen Demand (COD) removal and colour reduction were studied. COD removal efficiency of 26% and decolourization efficiency of 44% were recorded for the wastewater treatment. The optimised conditions for the biological treatment were found to be at 16.37 g/l of bacterial powder at 25°C for COD removal and colour reduction. The optimised parameters can be used for biological treatment of yeast plant effluent for removal of organic load and colour.


Key words: Cultured bacteria, wastewater, treatment, response surface methodology