Full Description

The State of Connecticut Department of Environmental Protection's enactment of the Water Treatment Wastewater (WTW) General Permit (GP) challenges operations personnel and design engineers to develop alternative methods of treatment and/or disposal of water treatment residuals. The South Central Connecticut Regional Water Authority (Authority) and the BHC Company (BHC), two of the largest water utilities in Connecticut, currently face complex residuals management issues in light of new and changing regulations. Regulatory, performance, and operational issues include the following: iron and manganese concentrations in the groundwater discharges in excess of WTW GP limits; water quality impacts of recycle streams from residuals treatment processes; the influence of a coastal climate on the freeze-thaw dewatering process; and, solids carry over in lagoon decant during cold temperature conditions. Over the past 10 years, several residuals management alternatives have been evaluated on either a full scale or pilot scale basis at the Authority's largest two WTPs that include the use of freeze-thaw lagoons, gravity thickening, mechanical dewatering, discharge of residuals to the sanitary sewer, and trucking of liquid residuals to wastewater treatment plants. Based on these evaluations, improvements are currently under construction at two of the Authority's treatment plants that include the installation of polymer feed systems and gravity thickeners for thickening and storage of residuals and loading stations for trucking of thickened liquid residuals off-site for disposal. The residuals improvements will provide operational flexibility, facilitate groundwater discharge compliance, and eliminate a recycle stream at one of the facilities that potentially impacts treated water quality. Various strategies have been identified to address the regulatory issues associated with the current residuals treatment practices at the other four facilities that include operation modifications to optimize existing practices, hauling of liquid or thickened residuals off-site for disposal, and on-site treatment.

Product Details

Published: 01/01/1999 ISBN(s): 1583210016 Number of Pages: 16File Size: 1 file , 510 KB