Date of Award
Doctor of Philosophy
Civil, Construction, and Environmental Engineering
Timothy G. Ellis
Research demonstrated three different bioreactors to evaluate use of tire rubber as biofilm attachment media in bioreactors for wastewater treatment: aerobic biofilter, anoxic bioreactor, and a hybrid anaerobic static granular bed reactor (SGBR). In addition, owing to the results from non-toxicity to microorganism and good surface area for biofilm attachment, size distribution, chemical composition, scanning electron microscopy, and whole effluent toxicity analyses verify the potential of TDRP (tire derived rubber particles) usage for biofilm attachment media. The trickling filter system using chunk rubber (average diameter of approximately 3 cm) achieved 79.6-90.1% COD removal efficiency at organic loading rates ranging from 0.12 kg COD/m3∙d to 0.34 kg COD/m3∙d. The hybrid SGBR and anoxic TDRP filter filled with fine rubber particles (average particle diameter of approximately 0.2 mm) achieved 90-97% of COD removal and above 97% of nitrogen removal, respectively at various hydraulic retention times of 48 to 20 h. The utility of TDRP media in multiple biofiltration applications was demonstrated by the performances of three TDRP biofilm media systems and analysis of TDRP characteristics. The biofilter system filled with TDRP filter media was utilized to treat the odorous gas contaminant, hydrogen sulfide. This bioreactor system achieved over 94% removal efficiency at 20-90 ppm of inflow H2S concentration while operating in 20-67 seconds of EBRTs, indicating that overall effective operation was performed at mass loading rates of H2S ranging from 19.6 to 28.5 g H2S/ m3 /hour. It was apparent by the effectiveness of the system’s performance that this system had the capability to hydrogen sulfide. Performance between the hybrid SGBR with the addition of TDRP and SGBR reactors was compared to validate the ability of TDRP media as a substitute for granules. Both systems showed similar high COD removal efficiencies (over 95%) at hydraulic retention times of 48 to 12 hours and resulting organic loading rates of 1 kg/m3/d to 4 kg/m3/d. The applicability of TDRP media to the bioreactor was also shown by the differences in performance between reactors with and without TDRP addition in the same granular sludge volume. An on-site pilot-scale SGBR system was evaluated for treating slaughterhouse wastewater from a food plant in Iowa to provide treatability and compared to other high-rate anaerobic systems and critical elements for commercialization. High organic removal efficiency (over 95% of TSS and VSS removal) was obtained due to the consistent treatability of SGBR system during operation at HRTs of 48, 36, 30, 24, and 20 hours. An effective backwash procedure was performed to waste a portion of the accumulated solids in the system. This procedure limited the increase in hydraulic head loss and maintained the system stability. COD removal efficiencies greater than 95% were achieved at organic loading rates ranging from 0.77 kg/m3/d to 12.76 kg/m3/d. This performance was consistently better than other high-rate anaerobic systems treating slaughterhouse wastewater.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu
June 1, 2013
Park, Jaeyoung, "Evaluation of tire derived rubber particles as biofilter media and scale-up and design considerations for the Static Granular Bed Reactor (SGBR)" (2008). Retrospective Theses and Dissertations. 92.