ClorTec™ On-site Disinfection Helps Ensure Safety at British Columbia Water Treatment Facility
Constructed in 1997, the District of Chetwynd Water Treatment Plant (British Columbia, Canada) treats nearly 2,500 cubic meters of water per day using gas chlorination as its primary form of drinking water disinfection. With recent concerns about the safety of chlorine gas, including potential eye, skin and respiratory irritation and the risk of death with high exposure, the district elected to switch to hypochlorite generation as its primary means of disinfection.
Al Tricker, chief operator at the facility, recognizing that the 12-15% concentration solution strength of potable grade bulk sodium hypochlorite is considered a hazardous material, recommended the use of an on-site generating system,
which produces a hypochlorite solution concentration of 0.8%. The use of on-site sodium hypochlorite generation offers significant advantages over the use of gaseous chlorine for disinfection. The disinfectant is produced and stored in liquid form, so the danger of gas leaks from high pressure chlorine cylinders is not present. As a result, it is not necessary for on-site sodium hypochlorite generating system users to develop and maintain a Risk Management Plan. Utilities using on-site systems do not need to provide HAZMAT training or provide for the availability of selfcontained breathing apparatuses.
Generating sodium hypochlorite on-site is a simple process that uses three common consumables: salt, water and electricity. The system operates by feeding softened water into a brine dissolver. The salt dissolves to form a brine solution, which is further diluted to the desired salt solution. The salt solution is then passed through the electrolytic cell(s), which apply a low voltage DC current to the brine to produce the sodium hypochlorite. The sodium hypochlorite is then safely stored in a 3,700 liter, five-day tank, and when it reaches the low-level set point the system automatically restarts to replenish its supply.