One Great View

April 30, 2007

About the author: Tim Gregorski is editorial director for Water & Wastes Digest. He can be reached at 847/391-1011 or by e-mail at [email protected]

NAME: Lakeview Water Treatment Plant

LOCATION: Region of Peel, Ontario, Canada

PLANT SIZE: 244 mgd—96 mgd specifically from expansion of Lakeview Plant

INFRASTRUCTURE: Expansion of Lakeview Water Treatment Plant has added almost 40% more treatment capacity due to installation of ultrafiltration (UF) membranes. Despite significant expansion, the plant footprint increased less than 7%. UF membranes added redundant treatment capacity in the short-term; however, long-term plans include additional expansion to allow treatment capacity to reach 303 mgd.

In 2000, seven people died and hundreds become ill in Walkerton, Ontario, after drinking water contaminated with E. coli and campylobacter bacteria. This tragedy sent shockwaves not only through local communities and the Canadian government, but also the drinking water industry.

In 2002, the Ontario government created the Ontario Safe Drinking Water Act to strengthen drinking water safety in the province by converting quality objectives into legally binding standards that govern the treatment and distribution of drinking water.

Forward now to 2007, and to the Lakeview Water Treatment Plant, arguably the most advanced and largest water treatment facility in Canada.

There is no doubt technological advancements in the water treatment industry are due in part to the Walkerton tragedy and have helped improve drinking water safety around the globe.

First of its kind

Located along the shores of Lake Ontario, the Lakeview Water Treatment Plant’s intake is located relatively close to the outfall of one of the area’s wastewater treatment plants. Because of this and recreational use in the area, the water quality fluctuates.

In order to treat the inconsistencies in water quality, the expansion of the Lakeview plant was not only designed as the world’s largest immersed membrane UF plant, but also as the first large-scale water treatment plant to combine ozone and biologically activated carbon (BAC) pretreatment with immersed membranes.

According to engineers from CH2M Hill, this solution provides consistently high drinking water quality, while also being treated in a small plant footprint at significant cost savings.

A number of pilot tests were conducted to examine various treatment options, and it became evident that a unique treatment method was needed to effectively treat the wildly fluctuating water quality. As a result, engineers opted for the ozone and BAC pretreatment method followed by membrane filtration.

The Region of Peel settled on the ZeeWeed UF membranes, manufactured by GE Water & Process Technologies. The region opted to take advantage of these particular membranes not only for their performance, but also because of the ability to add future membrane treatment capacity to the current expansion, while concurrently reducing future expansion costs.

Looking ahead, the Region of Peel worked with CH2M Hill to develop an alternative design that increased plant capacity 39% (from 70 to 96 mgd) with only a small increase in footprint. This increase of treatment capacity serves as a basis for future expansions within the plant, which is expected to reach 303 mgd by 2013.

The treatment process

The treatment process starts by adding chlorine at the plant intake to control zebra mussels. The water is then prescreened and pumped to a feed header that can supply either the original treatment plant or the expansion portion.

Water destined for the treatment train in the expansion plant is treated with a caustic to adjust the pH to a level acceptable for the biologically activated carbon treatment process as well as to help minimize corrosion in the distribution system. Ozone is added to inactivate Cryptosporidium and oxidize organic compounds that cause taste and odor problems. Sodium bisulfate is then added to the ozone-contacted water prior to the biologically activated carbon treatment process.

After ozonation, the water travels by gravity to deep-bed activated carbon filters for removal of organics and additional taste and odor control as well as turbidity removal. From this point, the water flows to the membrane filtration tanks to remove any remaining particles and pathogens.

Chlorine and fluoride are added to the water before it flows into the plant’s 6.7 million gal reservoir. Finally, a new high-lift pumping station sends the water from the reservoir throughout the distribution system.

Community benefits

The treatment technologies and monitoring protocols at the Lakeview Water Treatment Plant are among the strictest in the industry, which ultimately benefits the local citizens.

“Water is an essential service, but most people take it for granted,” said Kathy Sims, technical analyst for public education and outreach in the Region of Peel’s Public Works office. “Most people don’t think about the technology and processes used to treat water; that’s why some private water companies can scare them into questioning the safety of their water. The region’s outreach program is designed to educate people about what we do to make sure that their water is clean and safe.”

About the Author

Tim Gregorski