This report aims to provide guidelines for the preliminary design of faecal sludge treatment schemes comprising solids-liquid separation and stabilization ponds. The document is based on research undertaken in Ghana.
|Title||Solids separation and pond systems for the treatment of faecal sludges in the tropics : lessons learnt and recommendations for preliminary design|
|Year of Publication||1998|
|Authors||Strauss, M, Heinss, U, Larmie, SA|
|Secondary Title||SANDEC report|
|Publisher||Water and Sanitation in Developing Countries (SANDEC)|
|Place Published||Duebendorf, Switzerland|
|Keywords||ammonia, anaerobic lagoons, design criteria, facultative lagoons, ghana, human excreta, pretreatment, recommendations, research, sanitation, sdiafr, sdisan, sedimentation tanks, septage, sludge dewatering, sludge drying beds, sludge treatment, standards|
This report aims to provide guidelines for the preliminary design of faecal sludge treatment schemes comprising solids-liquid separation and stabilization ponds. The document is based on research undertaken in Ghana. The document examines the results of field research conducted on faecal sludge pretreatment; i.e.: solid-liquid separation in sedimentation/thickening tanks and dewatering/drying beds. Solids-liquid separation in sedimentation units prior to the pond system has been found to contribute to considerable land saving and to simplify pond operation as compared to schemes where solids-liquid separation is integrated in the primary pond. One of the main chapters in this document, covers anaerobic pond technology for high-strength wastes and the results of field investigations conducted with anaerobic ponds. Use of facultative ponds is also described, with particular focus on ammonia toxicity for algae from high ammonium levels in fresh and highly concentrated faecal sludges. Effluents and solids quality standards for faecal sludge treatment plants are discussed and a set of guideline values proposed. The authors recommend schemes comprising anaerobic and facultative ponds and a separate pretreatment stage for solids-liquid separation as a suitable technical option for the treatment of low to medium-strength sludges, such as septage. Guidance on the preliminary design of such schemes is provided. It is suggested that high-strength, fresh and largely undigested sludges, typical of bucket latrines and unsewered public toilets, do not lend themselves to solids-liquid separation and, hence to pond treatment. In addition, high ammonia levels, may inhibit the anaerobic stabilization process either in anaerobic ponds or in digestion tanks.
|Custom 1||341.1, 342|
|Original Publication||Workshop on faecal sludge treatment : Sogakope, Ghana, 3 - 5 December 1997 :|