The Largest Ultrafiltration Water Treatment Plant In North America Chooses Immersed Membrane Technology

ZENON's ZeeWeed technology proves to be the perfect fit

The largest ultrafiltration contract awarded in municipal water treatment will use ZENON technology to make history.

The Olivenhain Municipal Water District's (OMWD) new treatment facility represents North America's largest ultrafiltration contract to date. When completed, the primary plant will produce 94,500 cubic meters per day (m3/d) for the district with an additional 13,000 m3/d of permeate being produced from filter backwash in a secondary facility resulting in a 99% recovery.

Perhaps as big a story as the treatment plant itself is the extensive evaluation process that took place to identify the successful company and product to handle these monumental demands.

With the advent of various new approaches to water treatment over the years, Olivenhain's Board of Directors and its consulting engineer, Boyle Engineering, resurrected the old practice of putting each proposed treatment system to the test…head to head. "We needed to make this a proposal process rather than a bidding process", commented Doug Gillingham, Project Manager, Boyle Engineering. "Each company had their own proprietary technology and we felt it was extremely important that we compare "apples to apples".

In an effort to ensure that each treatment system was fairly assessed, the OMWD and Boyle set out to put each pre-qualified system through a rigorous review.

The District went through extensive research comparing the merits of membrane technology versus conventional treatment. "The plant needed to be capable of handling a variety of water qualities. In Southern California we knew a lot about reverse osmosis and had been watching micro- and ultrafiltration emerge as viable alternatives in the water treatment marketplace," said David McCollom, General Manager of Olivenhain. "Some of the decision factors for membrane filtration included the ability to treat water without a lot of chemicals and not having to dispose of a lot of sludge."

The membrane systems go head-to-head

In the first step of the evaluation process each competing company was asked to provide a pilot treatment system to the US Bureau of Reclamation Water Quality Improvement Center (USBR WQIC) in Yuma, Arizona, to be used for field testing. Studies were then conducted to determine the performance capabilities of microfiltration and ultrafiltration membranes on the Colorado River.

Upon completion of the Arizona assessment, each system was transported to San Diego for a true measure of how the technology would stand up against the California requirements. After this final evaluation stage, and some 12 months later, the remaining companies prepared for an on-site interview in order for OMWD and Boyle to get a clear picture of the people and companies involved with each technology.

And then there was one

Soon after this final step the announcement of the ZENON partnership was made. "Clearly, each competing company had tremendous qualities in both their systems and their people," observed Kimberly Thorner, Esq. Project Administrator with OMWD. "ZENON best met the present and future water treatment needs of the District". David McCollom called attention to the specific issues surrounding the Olivenhain project. "We needed a treatment plant that we could build initially to handle a specified treatment capacity and then could easily be expanded. We also had a confined space in a valley where we were going to build and there were several environmental concerns." ZENON's ZeeWeed immersed membrane technology proved to be the perfect fit."

It was interesting that during the entire evaluation process ZENON seemed the most reserved. It was almost as if they wanted to let their product/process speak for itself," Ms. Thorner suggests.

With the awarding of the Olivenhain contract, ZENON, who currently has a number of membrane filtration plants online, including Collingwood, ON (28,000 m3/d) and Thunder Bay, ON (36,000 m3/d), has positioned itself as a leader in membrane filtration.

The technology

ZENON's ZeeWeed technology is quite remarkable. It uses a patented "suction" system that provides over 6 log removal of Cryptosporidium and Giardia and up to 4 log removal of viruses. The low pressure applied to the membrane, coupled with the reinforced structure means further savings due to a very long operating life. The modular format and small footprint means that it offers extremely cost-effective opportunities for expanding municipal facilities by fitting in existing tanks, or in the case of Olivenhain, the ideal choice for new construction.

"The ZENON ultrafiltration system is a 'vacuum' system and will result in an easier to maintain, more robust system, capable of meeting the new and more stringent California Department of Health Services and Federal drinking water requirements," remarked the OMWD board in their recent press release highlighting the new partnership.

"Although all competing technologies were impressive, ZENON stood out because of its ease of operation and maintenance, its convenient adaptability and its durability," concluded Doug Gillingham of Boyle. When you couple the technological capabilities of their system with the experience, creativity and integrity of their people, ZENON is making quite a name for themselves. Kimberly Thorner, Esq. Project Administrator in the OMWD project put it this way, "ZENON's proposal to our District was cost competitive, solid throughout and very creative. We stand to save millions of dollars when compared to our initial design concepts. We were impressed by both the high quality of their product and the skills and expertise of their staff."

The road ahead

What is also most impressive about this entire venture is the advancement the entire industry will make as a result of this facility. Ann L. Peay, President of the OMWD Board of Directors said of the new partnership…" Olivenhain Municipal Water District is underway with a project that will set the example of the future of water treatment in the water industry. Not only will the District have the biggest ultrafiltration plant of its kind in the world, but the best".

This article appeared World Water Magazine, May 1999.