Faecal sludge management in Accra, Ghana
Faecal sludge management is a major challenge in the Greater Accra Metropolitan Area (GAMA), as in many developing countries around the world. Faecal sludge matter is often not properly handled and treated to meet the applicable environmental standards. In some cases, faecal matter is dumped directly into water bodies, open sea and/or open dump sites, resulting in dire health and environmental consequences.
Witteveen+Bos, acting as sub-contractor to Colan Consult, is responding to the World Bank’s call for tenders to provide ‘consultancy services for update assessment and strategic planning of liquid waste management in the Greater Accra Metropolitan Area’. The project brief estimated that about 90 % of public and household toilets in GAMA use on-site technologies. Effluents from these on-site toilet facilities are collected from septic tanks, holding tanks and pan and pit latrines for subsequent disposal. It was also estimated that over 1,200 m3 of faecal/septic sludge was generated in GAMA every day. However, at the start of the project there was not a single operational faecal/septic sludge or septage treatment plant in GAMA.
Witteveen+Bos conducted the technology review and the technical audit of facilities and sites, and prepared the preliminary engineering design for two innovative and sustainable faecal sludge treatment facilities in Accra. Experts from Witteveen+Bos also assisted with presentations and workshops organised as part of the assignment. Designs were drawn up for a sophisticated combination of physical and biological faecal sludge treatment technologies and reject water treatment. Sludge thickening and dewatering with screw presses will be applied, as well as anaerobic treatment of the faecal sludge using a balloon digester and biogas production and facultative pond systems for reject water. The so-called Pivot process was selected for thermal and greenhouse sludge drying facilities for the treatment of 600 m³/day of sludge at the Nungua site to the east of Accra. The second faecal sludge treatment plant has a design treatment capacity of 1,500 m³/day and will be equipped with an upflow bed filter combined with pivot works to produce biofuel (briquettes).