IMPROVED DEWATERING AND INCINERATION FACILITIES AT THE FIELD'S POINT WWTF

In 1995, PBS&J was retained by the Narragansett Bay Commission to study and design improvements to the dewatering and incineration facilities at the Field's Point Wastewater Treatment Facility. In the process of designing the various facilities, several unique evaluations were undertaken, including the following:Dewatering evaluation: The project began with a conventional comparison of dewatering technologies, between belt filter presses and centrifuges. Once the initial selection of centrifuges was made, the process proceeded to an in depth evaluation of centrifuge technology and manufacturers. The evaluation included the following steps:Two centrifuge pilot testsAn evaluation of technical information from the manufacturersUser contact of various centrifuge installationsRecommendation of procurement strategy to the NBCDevelopment of a request for proposalsEvaluation of proposal submittalsSelection of centrifuge manufacturerAir pollution control evaluations: The existing incinerator meets all existing air pollution regulations. However, the NBC decided to take a proactive approach and evaluate potential future regulations. In addition, there were potential improvements which could improve the operation of the existing incinerator. The evaluations included the following:An evaluation of potential future regulationsComparison of technologiesCost comparison for both current and future needsEvaluation of alternatives, keeping in mind potential future requirementsSelection of appropriate air pollution control equipment.The selected dewatering and air pollution control technologies were implemented into a two phase design of new facilities. The new dewatering facilities (Phase I) will include liquid sludge storage, high speed centrifuges, high solids pumps, combined dry and liquid polymer system, backup lime stabilization and truck loading systems, and packed tower odor control. Steps were taken in the design to improve operation and reduce costs.The new incineration facilities (Phase II) will include a wet electrostatic precipitator for particulate removal, flue gas recirculation for nitrogen oxide removal and improved performance, as well as overfire air systems for improved incinerator performance.Each phase will have state-of-the-art control systems to function with the plants existing distributed control system. Ultimately, the new facilities will allow for improved maintenance and performance of an aging dewatering and incineration system.