(248d) Alternative Energy through Optimization of Methane Formation by Anaerobic Digesters in Municipal Wastewater Treatment Plants

The operating parameters of anaerobic digesters were optimized to maximize biogas production at the Hilliard Fletcher Wastewater Treatment Plant in Tuscaloosa, Alabama. This process makes use of a renewable resource, municipal waste and wastewater, to produce relatively clean biogas. Currently, most of the produced biogas is burned to heat the anaerobic digesters. However, optimization of this process could result in additional production of biogas which can be converted to electricity and increasing the overall energy efficiency of this and similar water treatment facilities.

Current research focuses on the four distinct steps of the batch anaerobic digestion process as well as determining the affect of operating parameters on gas production. Parameters of interest include pH, temperature, alkalinity, and volatile fatty acid concentration. Our observations show that pH plays a very important role in determining the quality of biogas produced. Contrary to the literature values of 6.5 ? 7.5, the optimum pH range during batch trials has been 5.6 ? 6.4. During this range, biogas composed of 64 mol % methane was formed, exceeding the highest methane content seen in plant gas samples. Additional results will be given for batch sensitivity trials and implementation of recommended operating parameters in a continuous laboratory scale system. Comparisons will be made with operation at the full scale facility.