Characterization of performance and monitoring of the upflow anaerobic sludge blanket reactor

Upflow Anaerobic Sludge Blanket (UASB) reactors have numerous applications for wastewater treatment in the food industry. Anaerobic granules used in UASB reactor systems are aggregates of microbial consortia performing anaerobic degradation (hydrolysis, acetogenesis and methanogenesis) of organic carbon present in waste water. The high microbial density of these granules and the resultant high rate of biological treatment process allow excellent treatment performance in small reactor volumes. The wide range of potential applications coupled with the complexity of the UASB process demonstrate the importance of developing strong engineering and scientific knowledge to achieve stable and controlled performance. This study focused on describing overall performance of an UASB reactor treating a synthetic brewery waste using anaerobic granules. Work included characterization of UASB reactor hydraulics, metabolic performance, monitoring and modeling of UASB reactor performance.; Hydraulics of an UASB reactor was studied using LiCl as tracer and stimulus-response technique to evaluate effects of organic and hydraulic flux on reactor mixing. Three existing flow models were evaluated using the experimental data. Two new models were developed to describe the UASB reactor hydraulics at low and high OLR. UASB reactors represented non-ideal flow reactors for the experimental conditions tested (ranging from 4-10 kgCOD/m{dollar}sp3{dollar}bed-d OLR and 12 hrs-2days HRT). Increased gas production, a result of increased OLR, reduced dead volume and improved reactor mixing at a HRT of 12 hrs.; Substrate utilization kinetic studies were conducted for anaerobic granules collected from the UASB reactor treating a synthetic brewery waste. Mass transfer within liquid boundary layer and within granules and temperature effects on acetate utilization were evaluated. Whole granules, partially disrupted granules and granule flocs, developed by mechanically disrupting granules, were tested. Temperature was varied from 26{dollar}spcirc{lcub}rm C{rcub}{dollar} to 37{dollar}spcirc{lcub}rm C{rcub}.{dollar} Substrate used for mass transfer experiments included acetate, propionate and ethanol. Intrinsic kinetic parameters km and Ks, for acetate, propionate and ethanol, were estimated using granule flocs. The effectiveness factors of whole granules, {dollar}eta,{dollar} were 0.32, 0.41, 0.75, for acetate, propionate and ethanol, respectively.; Microbial conversion of ethanol using anaerobic granules was conducted to examine the fate of substrate, metabolic intermediates, and final products during ethanol degradation. Free energy analysis was performed for 14 major potential reactions. Based on the observation of n-propanol production, the n-propanol pathway was studied using {dollar}sp{lcub}13{rcub}{lcub}rm C{rcub}{dollar}bicarbonate to evaluate the role of CO{dollar}sb2{dollar} in formation of n-propanol during ethanol degradation. Anaerobic granule physical structure and microbial populations were examined using light and Confocol microscopy.; Responses of the trace gases H{dollar}sb2{dollar} and CO and reactor performance during various hydraulic loading rates, organic loading rates and variation in feed composition at pseudo-steady state of an UASB reactor were examined. Unsteady state monitoring experiments were conducted to study the potential use of H{dollar}sb2{dollar} and CO as indicators for the UASB reactor system, to detect onset of unstable conditions (organic overloading) and system failure. Statistical analyses were performed.; A dynamic mathematical model incorporating reactor hydraulics, substrate utilization kinetics and mass transfer within granules was developed for the UASB reactor. Numerical methods were used to solve the model. Sensitivity analyses for model parameters were performed. The model was calibrated using data from the acetate impulse experiment and then evaluated with acetate step increase experiments.