Because of these impacts on finished water quality and the anticipated new regulations for handling waste filter washwater, the Commission has investigated alternatives to better handie these flows and improve finished water quality. Based on successful pilot testing at another facility, one alternative is to treat the waste filter washwater and decanted settling basin supernatant with microfiltration, and to use the microfiltered water as potable water or to recycle this water to the head of the WTP. The concentrated solids from the microfiltration unit would be discharged to the Residuals Treatment Facility or the lagoon. This paper presents the results of pilot testing microfiltration for this application and a preliminary engineering evaluation of alternative plans.
Microfiltration for treatment of waste filter washwater at water treatment plant
The North Jersey District Water Supply Commission (Commission) serves about 2 million consumers from its 210 mgd water treatment plant (WTP) in Wanaque, New Jersey, about 25 miles northwest of Manhattan. Raw water is obtained primarily from the adj acent Wanaque Reservoir, and the nearby Pompton and Ramapo Rivers. The Wanaque WTP provides conventional treatment with chiorine as primary disinfection. Waste filter washwater and supernatant from cleaning the settling basins is recycled to the head of the WTP after passing through a holding/equalization basin. Settling basin sludge flows to either the Residuals Treatment Facility or a sludge lagoon. The lagoon also accepts decant water from sludge dewatering. Lagoon supernatant is recycled to the reservoir. Occasionally, the recycle flows disrupt the operation the WTP and impact finished water quality.