An overview of the current literature-based knowledge regarding faecal sludge (FS) treatment along with the results and conclusions from own field research are presented. Issues for further faecal sludge treatment studies are also addressed. The article focuses firstly on the characteristics of the various types of faecal sludge. A set of variables is proposed for minimum faecal sludge determination and faecal sludge treatment plant (FSTP) design and control. Priority treatment options particularly relevant to developing and newly industrialising countries are listed. They include solids-liquid separation by settling/thickening processes, sludge dewatering and drying in drying lagoons or drying beds, stabilisation ponds, and co-composting with refuse or other bulking/organic material of high carbon content. The results of in-depth monitoring of a faecal sludge treatment plant in Accra, Ghana, are reported. The plant receives septage and public toilet sludge and comprises solids-liquid separation by settling/thickening followed by a series of four ponds for the treatment of the liquid fraction. The four ponds in series all function as anaerobic ponds. Facultative pond conditions do not develop. This appears to be due to the suppression of algal growth through high levels of ammonia (NH3). Final effluent BOD is 300 mg/l as against 2,000 mg/l in the raw sludge mixture and 1,600 mg/l in the sedimentation tank effluent.

Waste stabilisation ponds are a widely accepted and proven technology to treat wastewater. It is often stipulated (and also practised) that the design of ponds for faecal sludges (FS), septage in particular, should follow the same principles as for wastewater. Field research conducted by SANDEC and its partners at the Water Research Institute in Ghana, and information gathered from the scarce literature on FS treatment, however, has shown that design principles should be taken into consideration, which are specific to the treatment of FS. These principles depend on the type of FS to be treated and on the type of pond system envisaged. Issues dealt with in this article are the handling of FS solids; the role of anaerobic ponds in FS treatment; the anaerobic degradability of septage; and ammonia (NH3–N) toxicity.

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Developing nations like Ghana, cannot afford to adopt a “wait to see” policy with their water environment. We must develop and/or strengthen infrastructure needed to maintain a healthy environment. In our eagerness to industrialize, care must be taken not to repeat mistakes of industrialized nations. Water quality monitoring activities should be streamlined and properly coordinated to develop good pollution control measures. We must research into and provide pollution control alternatives suitable for our particular environment.