Challenge

New Brunswick, New Jersey, one of the state’s oldest industrialized cities with roots dating back to 1730, needed to replace pressure filters at its 18 million gallons per day (MGD) surface water treatment plant. The existing plant supplies an average of about 12.5 MGD to residents of New Brunswick, Milltown and Franklin.

Built in 1916 with two clarifiers followed by eight gravity filters, the plant was upgraded with eight pressure filters in 1935 to expand capacity to 18 MGD. By 2002, the pressure filters reached the end of their useful life.

Based on an evaluation by engineering consultant Hatch Mott MacDonald (HMM), the city chose membrane filtration due to superior particle and pathogen removal, ease of integration and operation, and future expandability.

Solution

HMM and the city evaluated membrane filtration pilot systems from three manufacturers, with the Memcor® CS submerged membrane system ultimately selected for its smaller footprint, ability to handle changing feed water conditions such as winter temperatures and relatively low maintenance requirements.

In addition to the submerged membranes, the system included: clarified feed pumps; filtrate pumps; backwash supply pumps; clean-in-place (CIP) pumps, tank and chemical metering pumps; self-cleaning strainers; air scour blowers; compressed air system; all valves related to the membrane system; service access platform, and CIP waste transfer and neutralization pumps.

Results

In October 2006, the city broke ground on the $22 million plant upgrade. Membrane installation began in July 2008 and the submerged membrane system started up a month later. Since then, it 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.

Now the largest surface water membrane plant in New Jersey, the plant includes four membrane treatment trains, each with a capacity of 2.67 MGD, for a total membrane capacity of 10.7 MGD. Coupled with the existing gravity filtration systems, the submerged membrane system expanded capacity to 20.7 MGD, thus allowing operators to take one train offline without disrupting plant operations. The membrane system is designed for future expansion to 24 MGD, along with ability to convert existing gravity filters to granular activated carbon for taste and odor control.