Zhao, Y.Q.Y.Q.Zhao2011-09-232011-09-23Taylor & F2006-01Separation Science and Technology0149-6395 print1520-5754 onlinehttp://hdl.handle.net/10197/3174This research assessed the use of gypsum (CaSO4.2H2O) as a skeleton builder for sludge dewatering since polymer conditioning of sludge affected only the rate of water release, not the extent of dewatering. The use of gypsum as a physical conditioner, in association with a polymer, could improve sludge filterability. More significantly, gypsum serves as a skeleton builder, forming a permeable and rigid lattice structure that can remain porous under high positive pressure during the compression step after the cake growth of the filtration, thereby maintaining the size of the micro-passages through which water is expressed. Experiments using a high pressure cell apparatus showed that a further decrease of two to seven percent of the equilibrium moisture content of the sludge cake was achieved, for sludge thicknesses for dewatering of 1 to 10 cm, by the addition of gypsum with 60% of the original sludge solids when compared to the single polymer conditioning. The importance of the addition of gypsum in alum sludge dewatering is not only the improvement in the extent of dewatering, but also the potential application of transforming dewatered alum sludge from ‘waste’ for landfill to useful ‘fertilizer’ or to be used as filter medium/adsorbent for wastewater treatment engineering.201186 bytesapplication/pdfenThis is an electronic version of an article published in Separation Science and Technology, 41 (12): 2785-2794 available online at: http://www.tandfonline.com/doi/abs/10.1080/01496390600785558Alum sludgeConstructed wetlandsDewateringDisposalGypsumSkeleton builderWater treatment plant residualsConstructed wetlandsGypsumSewage sludge--ConditioningJournal Article41122785279410.1080/01496390600785558https://creativecommons.org/licenses/by-nc-sa/1.0/