an official journal of: published by:
Editor in Chief: RAFFAELLO COSSU


  • Charles B. Niwagaba - Department of Civil and Environmental Engineering, Makerere University, Uganda
  • Ajak Ezekiel Ayii - Department of Civil and Environmental Engineering, Makerere University, Uganda
  • Ambrose O. Kibuuka - Department of Civil and Environmental Engineering, Makerere University, Uganda
  • Raffaella Pomi - Department of Civil, Building and Environmental Engineering, Faculty of Civil and Industrial Engineering, University of Roma “La Sapienza”, Italy

DOI 10.31025/2611-4135/2019.13824

Released under CC BY-NC-ND

Copyright: © 2019 CISA Publisher

Editorial History

  • Received: 06 Apr 2019
  • Accepted: 30 May 2019
  • Available online: 28 Jun 2019


Sludge from the drinking water treatment plant at Ggaba III, located in Kampala (Uganda), was tested to evaluate the feasibility of two valorization routes, for building material and Solid Recovered Fuel (SRF) production. The aim of the research was to divert the huge amount of sludge produced every year, approximately equal to 2,140 metric tons of TSS/year, from landfilling. The average high heating value of the sludge was 8.44 MJ/kg TS, corresponding to the lower value of the interval of variation typically reported for other biosolids (8.0-23 MJ/kg). Different bricks were prepared at sludge to clay ratios of 0, 0.05, 0.1, 0.3 and 0.5 by weight. For each mixture composition, bricks of nominal size 215 x 102.5x 65mm were prepared by hand and fired for 6hrs in a Hoffman kiln at temperatures: 850°C, 900°C, 950°C, 1000°C and 1050°C. The bricks produced with a sludge to clay ratio of 0.1 fired at temperatures of ≥980°C met the compressive strength of 3N/mm2 for common bricks according to Ugandan Standard (US) 102:1995. These results suggest that water treatment sludge at Ggaba is more suitable for the production of common bricks than using it as an energy source. Given the encouraging results that make the studied valorization route applicable in an emerging economy country as Uganda, further investigations are required to assess the leaching behaviour and stability of the mechanical properties over time.


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