Title page for ETD etd-08142012-145531


Type of Document Master's Thesis
Author Bishnoi, Pallavi
Author's Email Address imvrpals@gmail.com
URN etd-08142012-145531
Title Effects of Thermal Hydrolysis Pre-Treatment on Anaerobic Digestion of Sludge
Degree Master of Science
Department Civil Engineering
Advisory Committee
Advisor Name Title
Novak, John T. Committee Chair
Boardman, Gregory D. Committee Member
Pruden-Bagchi, Amy Jill Committee Member
Keywords
  • cambi
  • odor
  • thermal hydrolysis
  • biosolids
  • anaerobic digestion
  • solids removal
Date of Defense 2012-07-31
Availability unrestricted
Abstract
The increased demand for advanced techniques in anaerobic digestion over the last few years has led to the employment of various pre-treatment methods prior to anaerobic digestion to increase gas production. These pre-treatment methods alter the physical and chemical properties of sludge in order to make it more readily degradable by anaerobic digestion. The thermal hydrolysis process has been used in several treatment plants around the world, but none currently operate in the US. Thermal hydrolysis causes cell walls to rupture under the effect of high temperature and high pressure and results in highly solubilized product which is readily biodegradable. The performance of the process was evaluated for a treatment plant located in Dallas, TX. The performance assessment was based on various characteristics including pH, solids removal, COD removal and gas production. The study was conducted in two phases to investigate the effect of change in mesophilic temperature (37oC and 42oC) and the effect of solids retention time (SRT) (15 days and 20 days). Thermally hydrolyzed combined (1:1) primary and waste activated sludge was fed to a Thermal Hydrolysis (TH) anaerobic digester and its performance was compared to a conventional mesophilic anaerobic digester receiving non pre-treated sludge. The thermal hydrolysis pre-treatment was found to be more effective as compared to the conventional anaerobic digester. The efficiency of the process varied slightly with increase in temperature but the change in SRT was seen to have a greater impact on the digester’s performance. The pre-treatment technique was observed to deliver the best results at a 20 day SRT.
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