Planning for Future Biosolids Energy Needs and Costs

This technical analysis summarizes the evaluation of Jones Island Water Reclamation Facility (JIWRF) future energy needs and develops multiple recommendations:What system is recommended if MMSD continues Milorganite (only) production at the JIWRF?What system is recommended if MMSD decides to add the Minergy process at the JIWRF to process a portion of the dried biosolids?How does the potential for landfill biogas influence the above recommendations?The energy requirements at JIWRF and biosolids need to be considered together at JIWRF because the two are intimately connected. The waste heat produced in the turbines during the generation of electricity to power the plant can be used to dry biosolids in the dryers to produce Milorganite, reducing the amount of natural gas that needs to be purchased to operate the dryers. However, energy requirements for sludge drying can change significantly from day to day or week to week while plant electrical requirements remain relatively constant. This energy analysis is based on the development of an hour-by-hour energy balance for the future energy requirements at JIWRF in attempt to better understand the complicated interconnection of the issues discussed above and how they change for different energy alternatives.