Title page for ETD etd-12182000-114810

Type of Document Master's Thesis
Author Bivins, Jason Lee
URN etd-12182000-114810
Title Changes in Dewatering Properties Between the Thermophilic and Mesophilic Stages in TPAD Systems
Degree Master of Science
Department Environmental Engineering
Advisory Committee
Advisor Name Title
Novak, John T. Committee Chair
Love, Nancy G. Committee Member
Randall, Clifford W. Committee Member
  • conditioning
  • biopolymer
  • dewatering
  • digestion
  • anaerobic
  • mesophilic
  • thermophilic
Date of Defense 2000-11-27
Availability unrestricted
Temperature-phased anaerobic digestion (TPAD) has become increasingly appealing in recent years due to the pathogen destruction capabilities of the system. However, there has also been concern about the dewatering properties of the sludges created by these systems. A laboratory study was conducted at Virginia Tech to determine the effect of thermophilic solids retention time (SRT) on sludge dewatering properties, to characterize system parameters associated with dewatering, and to understand the mechanisms causing changes in dewatering properties between the thermophilic and mesophilic phases. The study showed that while anaerobic digestion caused dewatering properties to deteriorate, sludges varied little with thermophilic SRT. Acidogenesis was essentially complete after 1.5 days. Subsequent mesophilic digestion resulted in little change to dewatering properties and modest reductions in conditioning doses, but substantial reductions in biopolymer (protein + polysaccharides) occurred. It appears that thermophilic anaerobic digestion creates or releases colloidal materials that cause dewatering to be poor and subsequent mesophilic digestion for 15 days does little to improve sludge properties of TPAD systems.
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