A lot has been going on at Nashville’s Central Biosolids Facility over the past 10+ years. There have been multiple projects resulting in seemingly never-ending construction. These projects have required unit processes to be taken out of service for extended periods of time, temporary flow paths, massive debris removal from existing tanks, contractors and engineers onsite all the time asking for things and getting in the way, not to mention the increased solids loading from a growing Nashville and an optimized Central Water Reclamation Facility (WRF). Metro Water Services (MWS) has been pushing the Biosolids Facility to its limits, often operating with essentially no redundancy. With optimization improvements complete and implementation of an updated biosolids master plan on the horizon, this presentation is an opportunity for all attendees to benefit from MWS’ experience dealing with increased loading, aging equipment, and other day-to-day challenges that were drivers for the upcoming facility expansion. Presentation will include: •A brief overview of the unit processes at the Central Biosolids Facility; mixed sludge and scum screening, dissolved air flotation thickeners, thickened sludge screening, anaerobic digestion, centrifuge thickening, and rotary drum dryers that produce Class A exceptional quality pellets that are beneficially used (sold) as a soil amendment (fertilizer). •A timeline of the multiple projects/improvements that have occurred over the past 10 years including their drivers, results, and lessons learned. Example: the facility experienced a catastrophic failure of a gas-holder cover in 2014. New fixed covers on all 4 primary digesters, internal draft tube mixers, passive overflow/standpipe digester outlets, and larger transfer pumps were implemented to address factors leading to the failure (poor mixing, rapid volume expansion, etc.). The final digester was recently completed, and efficiency/capacity has reached an all-time high. Photos of the failed cover, the improvements, and current operating data will be included in the presentation. •The addition of a sludge screening facility upstream of the Biosolids Facility in 2018, a relatively small project, has resulted in a tremendous improvement to the reliability of all downstream solids handling processes. •Optimization of the Central WRF liquid stream processes from 2022-2024 has resulted in improved solids capture in the primary settling tanks, consistent waste activated sludge pumping, and an overall reduction in final effluent suspended solids. Improved liquid stream treatment combined with a growing Nashville has resulted in all-time high solids loading to the Biosolids Facility. However, the increased loading is conveyed in a much more consistent manner, enabling more stable operation of solids handling processes and the need for fewer adjustments. Data showing the improved stability will be presented. The O&M staff has done an incredible job minimizing downtime of their aging rotary drum dyers, but both dryers are needed to process current peak loads to the facility. The addition of a 3rd dryer and other improvements recommended in a recently completed biosolids masterplan will be discussed at the conclusion of the presentation, if selected.