World’s largest low-pressure membrane system to be built in Canada
The region of Peel, one of Canada’s fastest growing municipalities will soon be home to the world’s largest low-pressure, ultrafiltration (UF) membrane drinking water facility. Located in southern Ontario, the region of Peel is preparing to expand its existing plant to meet the water needs of the rapidly increasing population and to ensure adequate water supplies for the area’s burgeoning businesses.
Upon completion of the expansion, Lakeview Water Treatment Plant (LWTP) will be the largest low-pressure, UF membrane plant in the world with a summer capacity of more than 80 mgd and a cold water (36°F) capacity of 69 mgd. Daily water treatment capacity of the plant will rise from the current 148 mgd to 216 mgd.
The objectives of the expansion stated that the plant should remain within the existing footprint, produce the highest quality drinking water at a reasonable cost and provide sufficient capacity to serve the region’s future needs.
Because a conventional water treatment system would not permit the LWTP to expand according to the specified criteria, the region began exploring alternative technologies. Working with engineering and design firm CH2M Hill, the region invited three leading membrane UF suppliers to participate in a comprehensive pilot program to test the suitability and performance of their products for the expansion. Factors such as reliability, longevity, cost, service, particulate removal and pathogens removal were all considered.
At the conclusion of the pilot study, the region of Peel decided to implement an innovative, multibarrier system at the LWTP incorporating ozonation, biologically active carbon (BAC) contactors and ZENON ZeeWeed hollow-fiber UF membranes.
“The ZENON ZeeWeed 1000 UF membranes represent the best available technology and the best long-term investment for Peel’s application,” said Mitch Zamojc, commissioner of public works for the region of Peel.
Ozone and BAC will provide pretreatment for the raw water prior to UF. This pretreatment process will reduce turbidity and dissolved organic carbon (DOC) as well as provide taste and odor control. Overall, the pretreatment will benefit the system with more consistent permeate quality, reduced energy costs, lower chemical consumption and a reduced risk of membrane damage.
“The ozone and BAC pretreatment will deliver a consistent quality feed water to the membranes with turbidity below 2.0 NTU, 95% of the time with total suspended solids below 5.0 mg/L (maximum of 40 mg/L) and DOC ranging from 1.0–5.0 mg/L,” said Mark Schiller, director of water and wastewater treatment for the region of Peel.
The LWTP expansion, scheduled for completion in 2006, will add 12 membrane process trains. Each train will consist of a 1,942 cu ft process tank that can hold up to seven ZeeWeed membrane cassettes. Eleven of the trains will operate at all times, with the twelfth train operating on demand.
The UF membrane cassettes are immersed directly into the membrane tanks and draw water into the fibers using a slight vacuum. The membranes form a physical barrier to particles, preventing suspended solids, turbidity, algae and pathogens such as Giardia and Cryptosporidium from passing into the permeate.
The operation of the system is highly automated and fibers can be easily cleaned with a clean-in-place backpulsing process that forces nonchlorinated permeate water back through the membranes. This dislodges any particles that may adhere to the membranes. Intermittent aeration of the membranes is also used to scour debris from the fibers. With regular maintenance and inspections, each membrane cassette will provide years of efficient and cost-effective operation.
Aside from the high quality drinking water that the new Lakeview expansion will produce, there are other benefits to the technology incorporated in the expansion. The compact size and greater efficiency offered by the newer technology, has spared Lakeview from expanding outside of its existing footprint. This means that a parcel of public land to the east of the plant currently used for baseball diamonds and parkland, can remain as the community’s recreational space.