Challenge

The city of Montreal needed a safe and reliable chlorination system for two of the city’s largest water treatment plants (WTPs) Atwater and Charles-J. DesBaillets. Combined, the plants treat roughly 2.4 million m³ (634 million gallons) per day and serve approximately 1.6 million residents with drinking water. The city recognising the benefits of on-site hypochlorite generation was convinced that the technology was the most suitable solution for these demanding sites. They ultimately selected OSEC® B-Pak hypochlorite generation systems by Evoqua Water Technologies over similar competitive technologies for their safety and cost effectiveness of the skid mounted solution. These plant optimizations were part of a multi-billion dollar project involving also the update of all WTPs as well as the distribution system on the Island of Montreal.

Solution

The replacement of a traditional gas chlorination system with the OSEC B-Pak hypochlorite generation system can help the city comply with the stringent government regulations for drinking water quality. A local consortium comprised of Filtrum Inc. and Evoqua Water Technologies provided the design, supply, installation, commissioning, and training of the multi-million dollar OSEC systems, which mark the largest such installations in Canada. The project specification required a bespoke solution to satisfy site requirements. Evoqua brought the Wallace & Tiernan experience of 35-years delivering OSEC system (over 1400 systems installed globally) to deliver a customized system.

Results

Five OSEC B-Pak 1500 systems were installed at the Charles-J. DesBaillets WTP for a capacity of 140 kg/h (7,500 ppd); six more were installed at the Atwater plant for a capacity of 168 kg/h (9,000 ppd). The Charles-J.DesBaillets site was commissioned in 2012 and the Atwater site was commissioned in 2015. Since then, the two sites have been enjoying the benefits of the OSEC on-site hypochlorite generation. By producing hypochlorite on site and on demand, the OSEC system eliminates concerns associated with transportation and storage of liquefied chlorine gas or commercial sodium hypochlorite solutions, making it ideal for any application requiring chlorination. And contrary to high-strength commercial sodium hypochlorite solutions, the low concentration of the hypochlorite solution generated by the OSEC B-Pak system minimizes corrosion and degradation. In addition, extensive safety measures are taken in disposing of hydrogen — the system’s only by-product. Neither special safety equipment nor clothing associated with usage of chlorine gas is needed, nor does a costly risk management plan need to be implemented and maintained.

The small footprint OSEC B-Pak skid system is a fully automated, pre-packaged on-site hypochlorite generation system designed for fast and economical installation, safe operation and easy maintenance. Skids are shipped completely piped, wired and tested. The OSEC system generates a 0.8% sodium hypochlorite solution through the electrolysis of brine, consuming only water, salt and electricity. The system also ensures accurate and reliable brine measurement for high efficiencies.