Anaerobic treatment of brewery wastewater and the effects of enzyme addition

Anaerobic treatment is becoming increasingly important to reduce costs of industrial wastewater disposal. However, there is a limited understanding of anaerobic technology due to the vast differences in wastewater streams and the variability in any biological process. This thesis focuses on the application of anaerobic treatment of brewery wastewater for organics and solids reduction. A pilot-scale EGSB anaerobic reactor containing aggregated biomass was used to study the effects of temperature on COD removal efficiency. The pilot reactor was able to tolerate temperatures between 60 and 120 °F, a full ten degrees both lower and higher than literature predicted. The biomass actually appeared to acclimate to the temperature extremes. The second portion of this research was an investigation of the potential application of commercial enzymes to improve anaerobic digestion of concentrated brewery solids. In batch tests, bacterial protease at concentrations above 30 ppm was found to significantly reduce the solids content over a period of ten days. Bench-scale anaerobic digesters were then used to test the enzyme in a more realistic setting. The protease at a concentration of 100 ppm was found to be unsuccessful at significantly reducing solids in the continuous digesters. However, proteases may be useful in assisting the digester in a quicker start-up and recovery from process upsets --Abstract, page iii