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Effects of Sludge Properties on the Thickening and Dewatering of Waste Activated Sludge
Author(s) -
Merlo Rion P.,
Trussell R. Shane,
Hermanowicz Slawomir W.,
Jenkins David
Publication year - 2007
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143007x183925
Subject(s) - activated sludge , thickening , dewatering , waste management , sewage sludge , wastewater , environmental science , sewage treatment , chemistry , pulp and paper industry , geology , geotechnical engineering , engineering
The thickening and dewatering of waste activated sludge, from a pilot‐scale submerged membrane bioreactor and two bench‐scale, complete‐mix activated sludge reactors (high‐shear and low‐shear aeration) treating the same municipal primary effluent, were investigated. Solids settling and compaction were measured using the diluted sludge volume index (DSVI) analysis and a batch centrifugation analysis, respectively. Elevated levels of filamentous microorganisms resulted in higher DSVI values and lower centrifuged pellet concentration. Elevated levels of nocardioform bacteria resulted in lower solids float concentrations, and higher colloidal material reduced solids recovery in batch flotation experiments. Sludge filterability, measured as time‐to‐filter, was shown to be a function of extracelluar polymeric substances and colloidal material, where higher levels of either reduced sludge filterability. Additional research is necessary to confirm these results using full‐ or demonstration‐scale thickening and dewatering units.