Upgrading Wastewater Facilities with Membrane Microfilters to Comply with NYC Watershed Rules and Regulations a case Study: Hobart, NY

In 2002, the Hobart Wastewater Treatment Plant (WWTP) selected hollow fiber microfiltration as the primary component of a tertiary treatment upgrade. The purpose of the upgrade was to ensure plant compliance with New York City (NYC) Department of Environmental Protection (DEP) Watershed Rules and Regulations. The 180,000 gpd WWTP discharges effluent directly into the West Branch Delaware River, which ultimately feeds the Cannonsville Reservoir, one of six NYC reservoirs in the Catskill/Delaware watershed. The Village of Hobart was required and funded under provisions in the DEP 1997 Memorandum of Agreement to further treat its extended aeration activated sludge effluent to meet monthly average State Pollution Discharge Elimination System (SPDES) permit limits for CBODM5 (25 mg/l), SS (10 mg/l), P (0.5 mg/l), N (8.2 mg/l as NH3), and fecal coliform (200 coliforms/100 ml). The plant was subsequently upgraded with tertiary treatment, which included coagulation/flocculation, multi-media filtration, hollow fiber microfiltration (MF), and low-pressure ultra-violet (UV) disinfection.The microfiltration system (Pall Aria™ AP-Series) is comprised of two primary 20-module membrane skids each designed conservatively at a flux rate of less than 23.3 gal/ft2/day (gfd) per DEP specifications. Each skid can independently accommodate maximum plant flow for full redundancy. A third auxiliary 7-module membrane skid processes backwash from the media filters and the primary MF system for greater overall recovery. The membrane system provides an absolute barrier for cryptosporidium and coliforms that could potentially pass through the multimedia filters. Downstream, the UV system further ensures the elimination of microbial contamination and the discharge of high quality effluent into the receiving body. After more than 5 years online, the plant has consistently met its SPDES permit requirements.This paper looks at the Hobart WWTP as a case study in the application of membrane microfiltration to a NYC Watershed Wastewater Treatment Plant upgrade as well as the effectiveness and reliability of a membrane filtration system as designed per NYC Watershed Rules and Regulations.