International Journal of
Water Resources and Environmental Engineering

  • Abbreviation: Int. J. Water Res. Environ. Eng.
  • Language: English
  • ISSN: 2141-6613
  • DOI: 10.5897/IJWREE
  • Start Year: 2009
  • Published Articles: 284

Full Length Research Paper

Wastewater treatment strategies of selected Zimbabwean food industries

Manhokwe, S.
  • Manhokwe, S.
  • Department of Food Science and Nutrition, 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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Mareesa, W.
  • Mareesa, W.
  • Department of Food Science and Nutrition, Midlands State University, P. Bag 9055, Gweru, Zimbabwe.
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Marume, P.
  • Marume, P.
  • Department of Food Science and Nutrition, Midlands State University, P. Bag 9055, Gweru, Zimbabwe.
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  •  Received: 22 May 2015
  •  Accepted: 01 February 2016
  •  Published: 31 May 2018

Abstract

This survey aimed at identifying the current practices and experiences of industrial wastewater treatment in Zimbabwe. In this study, questionnaires were used to assess various companies located in Gweru Kwekwe, Bulawayo and Harare. The information collected identified a gap in the treatment of wastewater from food processing industries in Zimbabwe. Current results indicate that about 86% of the food processing industries surveyed have primary treatment facilities. Few companies have proper secondary treatment facilities. Wastewater was characterised for selected effluents. Electrical conductivity (EC) of the wastewater was also recorded to be lower in most of the samples where dairy effluent showed highest EC by a value of 953 μS/cm. Total dissolved solids (TDS) were observed to be higher in dairy effluent as compared with other effluents. Total suspended solids (TSS) of cereal beverage effluent were higher with a value of 90 mg/L. The highest chemical oxygen demand (COD) values were recorded in potato processing effluent (690 mg/L O2) followed by meat processing effluent (485 mg/L O2). These values however are above the value recommended in S.I.6 of 2007 of 60 mg/L. It was noted that more than 80% of the wastewater comes from production processes and a substantial amount (53%) coming from raw material processing. This study indicates that regular inspections are done to enforce the wastewater legislation. Of all the companies studied, 73% of the companies were disposing their industrial effluent directly into the municipal sewer lines. Without the proper treatment facilities, the disposal of polluted effluent into the public sewer poses health and environmental consequences to the community. It can be concluded from the current data that there is a serious need to establish secondary treatment systems to remove organic load from food processing effluent and reduce pollution.
 
Key words: Wastewater, food processing, pollution, treatment, legislation, disposal.