African Journal of
Biotechnology

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12487

Full Length Research Paper

A two-stage decentralised system combining high rate activated sludge (HRAS) with alternating charcoal filters (ACF) for treating small community sewage to reusable standards for agriculture

Irene Nansubuga
  • Irene Nansubuga
  • LabMET, Faculty of Biosciences engineering, University of Ghent, Coupure Links 653, 9000 Ghent, Belgium; National Water and Sewerage corporation, Plot 39, Jinja Road, P.O. Box 7053, Kampala, Uganda.
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Francis Meerburg
  • Francis Meerburg
  • LabMET, Faculty of Biosciences engineering, University of Ghent, Coupure Links 653, 9000 Ghent, Belgium.
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Noble Banadda
  • Noble Banadda
  • Department of Agricultural and Bio-Systems Engineering, Makerere University, P.O. 7062, Kampala, Uganda.
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Korneel Rabaey
  • Korneel Rabaey
  • LabMET, Faculty of Biosciences engineering, University of Ghent, Coupure Links 653, 9000 Ghent, Belgium.
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Willy Verstraete*
  • Willy Verstraete*
  • LabMET, Faculty of Biosciences engineering, University of Ghent, Coupure Links 653, 9000 Ghent, Belgium.
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  •  Received: 14 October 2014
  •  Accepted: 10 February 2015
  •  Published: 18 February 2015

Abstract

 

Water scarcity increasingly drives wastewater recovery. Campaigns towards re-use of wastewater are not very common in Africa among other factors, due to a lack of efficient and cost-effective technology to treat wastewater to re-usable standards. In this study, two treatment systems, a high rate activated sludge (HRAS) system and alternating charcoal filters (ACF) are combined and used to treat wastewater to standards fit for reuse in agriculture. The charcoal can upon saturation be dried and used as fuel. Two different ACF lines were used in parallel after the HRAS: ACF1 with a residence time of 2.5 h and ACF2 with residence time of 5 h. Results show no significant difference (α = 0.05) in the performance of the two filter lines, hence ACF1 with a higher flow rate was considered as optimal. The HRAS effectively removed up to 65% of total suspended solids (TSS) and 59% of chemical oxygen demand (COD), while ACF1 removed up to 70% TSS and 58% COD. The combined treatment system of HRAS and ACF1 effectively decreased TSS and COD on average by 89 and 83%, respectively. Total ammonium nitrogen (TAN) and total phosphates (TP) were largely retained in the effluent with average removal percentages of 19.5 and 27.5%, respectively, encouraging reuse for plant growth.

 

Key words: A-stage, sustainable wastewater treatment, resource recovery, developing countries, water reuse, nutrient management, agriculture.

Copyright © 2024 Author(s) retain the copyright of this article.

This article is published under the terms of the Creative Commons Attribution License 4.0

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