Effects of sludge properties on the thickening and dewatering of waste activated sludge
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Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor
Published on: October 15, 2015
Rion P Merlo1, R Shane Trussell, Slawomir W Hermanowicz
1Brown and Caldwell, Walnut Creek, California 94596, USA. rmerlo@brwncald.com
Abstract:
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.
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