Energy from Wastewater Sewage Sludge in Lebanon

It is crystal clear that, in addition to clean air, the well-being of our planet also requires that water, wastewater and the resulting biosolids (sludge) need to be managed more seriously, and in a focused, coordinated and cooperative manner. The idea for the creation of this Global Atlas of Excreta, Wastewater Sludge, and Biosolids Management originated at the IWA Biosolids Conference, “Moving Forward Wastewater Biosolids Sustainability: Technical, Managerial, and Public Synergy” held in Moncton, New Brunswick, Canada in June 2007. At this conference representatives of the International Water Association (IWA), Water Environmental Federation (WEF) and European Water Association (EWA) agreed that it would be very useful to produce a current edition of the “Global Atlas of Wastewater Sludge and Biosolids Use and Disposal” which had been published in 1996, with Peter Matthews being the original editor.

INTRODUCTION Dewatering is a physical process integrated in the sludge line of treatment plant. It is aimed at reducing the water content and therefore the sludge volume. In this way, its transportation costs to the final destination point is reduced. On the other hand, the dewatered sludge is easier to handle and the transport process is more convenient than in the case of a sludge with higher water content. The dewatering technique chosen must be consistent with the amount and characteristics of sludges generated and with the biosolid final destination. Water present in the sludge exists in four forms (see figure): free, colloidal, intercellular and capillary. Free water can be separated from sludge by gravity as it is not associated with solids. Chemical conditioning prior to the use of mechanical tools is required in order to remove colloidal and capillary water. For intercellular water removal, the structure containing it must be broken and this can be done through heat treatment.