CT Consultants was selected by the Village of Carrollton to perform general planning and design of improvements to expand the Village’s Wastewater Treatment plant. Capacity expansion and treatment upgrades were necessary due to the facility operating near or above the permitted capacity during several months of the year. Additionally, the Village wanted to address the poor performance of the plant’s secondary treatment unit processes and influences of wet weather events.
CT Consultants evaluated several alternatives including an oxidation ditch process, sequencing batch reactors, and membrane bioreactors (MBR). The Village selected the expansion of the biological process from its average daily flow capacity of 0.5 MGD to 0.75 MGD to accommodate past and presently identified increased loadings by using a state of the art MBR process. While the life-cycle cost of the MBR is marginally higher, there were several benefits which included: site preservation for other improvements at the WWTP; cleaner effluent which has environmental benefits potential for reuse, and resistance to tighter future discharge limits; a feasible treatment alternative for I/I treatment which exceeds the plant’s normal treatment capacity and flow equalization capacity; and minimizing plant staffing.