New Brunswick, one of the country’s oldest industrialized cities, owns and operates a water system that serves a population of approximately 60,000, in addition to water delivered on a wholesale basis to two adjoining municipalities.
The City’s water treatment plant was built in 1916 with two clarifiers followed by eight gravity filters. Eight pressure filters were added in 1935, but by 2002 the pressure filters had reached the end of their useful life and required replacement.
A conventional surface water treatment facility, the plant had a design capacity of 20 million gallons per day (MGD), including raw water pumping, chemical pretreatment, flocculation, sedimentation, filtration and disinfection.
The City engaged Mott MacDonald to evaluate alternatives for replacement of the pressure filters, as well as to increase plant capacity.
We recommended a membrane filtration with enough capacity to replace the pressure filters and expansion capabilities sufficient to replace the gravity filters. We conducted pilot testing of alternative membrane systems, leading to the selection of an immersed membrane system.
Mott MacDonald was engaged to prepare the detailed design, including the following:
- New building to house the membrane system and associated pumps, chemical feed systems, backwash facilities and residuals handling facilities
- Complete replacement of the plant’s high-lift pumping system with a new 24 MGD system
- Complete renovation of the existing pressure filter building to house the new pumping system, electrical service, and distribution equipment for the entire plant
Construction for the upgraded plant began in 2006, and the submerged membrane system began operating in 2008.
New Brunswick now has the largest membrane water treatment plant in New Jersey. The system offers superior particle and pathogen removal, ease of integration and operation, a relatively small footprint, and relatively low maintenance requirements.
According to Water & Wastes Digest, “Since startup, the submerged membrane system has provided exceptional treated water quality along with operational flexibility, especially during periods of high water turbidity and iron. The open tank design allows the operator to visually inspect the performance of the system, particularly during integrity testing. What’s more, system performance has exceeded the expectations based on the previous pilot testing.”
The magazine also points out that the membrane system offers guaranteed compliance with the Interim Enhanced Surface Water Treatment Rule.
In addition to providing increased capacity to meet current demand, the renovated water treatment plant is equipped to handle increased demand in the future:
- Three membrane trains provide an initial capacity of 8 MGD. By adding membrane modules to the tanks, capacity can be expanded to 12 MGD.
- The plant is designed to accommodate three more trains, allowing an ultimate capacity of 24 MGD.
- The design allows for gravity filters to be converted in the future to granular activated carbon “polishing” filters, which would work in series with, and downstream from, the membrane filters.