Sludge treatment in hot climate

This thesis introduces the various sewage sludge treatment and disposaltechnologies in arid hot climate region in Egypt where the volume ofsludge is increasing and the potential is falling due to stringent qualityenvironmental requirements that can not be met. The sludge is lessrecycled to agriculture and has to be dumped on arid land.The techniques available in Egypt for this purpose make sludge disposalmuch more expensive. The thesis also plots the development of some ofthe current technology of sludge treatment in hot climate region.Many methods of sludge treatment were discussed carefully to select themost suitable methods for the Egyptian environmental.Thickening process was used for periods of 4 to 6 hours to raise the solidscontent form (0.5-2) % to (2-6)0/0 after thickening.Use of single stage high rate anaerobic digester instead of the two stageprocess was recommended to avoid economical increase in implementingthe second process as the efficiencies of both processes are quite similar.Results showed that a detention time of 20 days was considered suitable asper technical and economical aspects for use in sludge treatment process.This study addressed the development of sludge dewatering systemspecially in cities were no adequate land area is available for constructingconventional drying beds. Coagulants were added after withdrawal ofthickened sludge. Samples were tested with different coagulants dose so asto achieve maximum dewatering conditions. Different vacuum ratesapplication were also investigated using rates of25, 30, and 35 kN/m2.Tests were also conducted using mechanical dewatering (Hdyromats) toevaluate the effect of its presence at the bottom of drying beds on the long