کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4482214 1316851 2012 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Compression dewatering of municipal activated sludge: Effects of salt and pH
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فرآیندهای سطح زمین
پیش نمایش صفحه اول مقاله
Compression dewatering of municipal activated sludge: Effects of salt and pH
چکیده انگلیسی

Even after mechanical dewatering, activated sludge contains a large amount of water. Due to its composition and biological nature this material is usually highly compressible and known to be difficult to dewater. In the present work, two treatments (salt addition and pH modification) are proposed to highlight some aspects which could explain the poor dewaterability of activated sludge. Dewatering tests are carried out in a pressure-driven device in order to well examine both, filtration and compression stages. Physico-chemical parameters, such as surface charge, hydrophobicity, extracellular polymeric substances (EPS) content and filtrate turbidity are measured on the tested sludge, for a better analysis of dewatering results.The dewatering ability of the sludge is widely linked to the cohesion of the flocculated matrix and the presence of fine particles. Both treatments alter the flocculated matrix and release fine particles. The release of fine particles tends to clog both, the filter cake and the filter medium. Consequently, the filtration rate decreases due to higher resistances to the flow. On another hand, the polymeric matrix breakdown enables to release some water trapped within the floc to the bulk liquid phase and thus facilitates its removal, which tends to decrease the moisture content of the filter-cake. It also impacts the compression dewatering step. The more destroyed structures lead to less elastic cakes and thus a slower primary consolidation stage. At the opposite, the mobility of the broken aggregates within the filter-cake does not seem to be improved by size reduction (the kinetics of the secondary consolidation stage are not significantly modified).


► The dewaterability depends on flocs cohesion and the presence of fine particles.
► Both salinity and pH conditions alter flocs cohesion and release fine particles.
► The release of fine particles leads to clogging phenomena.
► Flocs breakdown enables to decrease the moisture content of the filter-cake.
► Flocs breakdown leads to a slower primary consolidation stage.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Water Research - Volume 46, Issue 14, 15 September 2012, Pages 4448–4456
نویسندگان
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