Title page for ETD etd-06192001-143911


Type of Document Master's Thesis
Author Muller, Christopher Dustin
Author's Email Address cmuller@vt.edu
URN etd-06192001-143911
Title High-Intensity Shear as a Wet Sludge Disintegration Technology and a Mechanism for Floc Structure Analysis
Degree Master of Science
Department Environmental Sciences and Engineering
Advisory Committee
Advisor Name Title
Novak, John T. Committee Chair
Love, Nancy G. Committee Member
Randall, Clifford W. Committee Member
Keywords
  • biodegradation
  • solids reduction
  • floc structure
  • disintegration
  • iron
Date of Defense 2001-05-29
Availability unrestricted
Abstract
By shearing activated sludge using a high shear rotor stator device, bioavailable proteinaceous material can be produced. Operation at elevated temperatures, serves to increase the amount of material that is rendered soluble (<0.45 um) and biodegradable. The storage of sludge under anoxic condition prior to shearing does not appear to enhance solublization of solids, though deflocculation and deterioration of dewaterablility was observed. Anaerobic digestibility appears to be enhanced by the addition of a high shear as shown by increases in gas production and volatile solids destruction. The dewatering properties of activated sludge, measured by capillary suction time, deteriorated with the addition of sheared solids, but reaeration resulted in near complete recovery.

The role of iron and iron chemistry plays a critical role in the activated sludge. Iron apparently selectively removes protein, in particular material ranging in the 1.5 um to 30K size range. The addition of ferric iron was found to increase SVI and decrease zone-settling velocity, when added to reactors with mechanically disintegrated sludges. Similar trends were not observed in reactors dosed with ferrous iron. Preliminary results suggest that the ferric/ferrous redox chemistry may serve to enhance floc structure, as observed by increased settling velocity and shear resistance for sludges dosed with ferrous sulfate.

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