Sludge accumulation in stabilisation ponds in the Soudano–Sahelian climate of Burkina Faso

ABSTRACT

Sludge accumulation in waste stabilisation ponds based on local conditions is of great interest for successful sludge management, and accurate accumulation data are essential for WSP design based on reasonable data for model development in relation to the effect of climate variability. For this purpose, a series of three ponds treating domestic wastewater in the Soudano–Sahelian climate of Burkina Faso were monitored for sludge accumulation. After five and a half years of operation, the rates of sludge accumulation in the ponds were evaluated at 0.019, 0.009 and 0.007 m³ per capita per year, respectively, for the anaerobic (AP), facultative (FP) and maturation pond (MP). The corresponding rates of accumulation in dry weight (dw) per person per year were calculated to 1.3, 0.43 and 0.26 kg dw per capita per year, respectively, in AP, FP and MP. A coefficient of high biodegradability of sludge was found in the AP. In contrast to the seasonal evolution of sludge accumulation reported in Mediterranean climatic conditions characterised by a succession of winter and summer, in Sahelian climate regions, a continuous digestion of sludge during its accumulation was observed, due to the warmer Sahelian conditions prevailing most of the year.

Keywords:

• Wastewater treatment
• Sludge accumulation rate
• Biosolids
• Waste stabilisation pond
• Burkina Faso

Acknowledgments

The authors would like to thank the International Institute for Water and Environmental Engineering (2iE), Swiss Development Agency, Swiss Federal Institute of Technology Lausanne (EPFL) and International Foundation for Science for their financial support. The authors also wish to acknowledge Professor Fatimata A. Pale and Professor Stewart Oakley for their editorial comments.

Notes

The Third International Congress Smallwat11—Wastewater in Small Communities 25–28 April 2011, Seville, Spain