The Maine Department of Environmental Protection’s Pollution Prevention (P2) Program concluded a successful grant project thanks to funding from the U.S. Environmental Protection Agency. Maine DEP worked with two public swimming pool owners to explore alternative technologies that will allow them to reduce their use of chlorine.
Chlorine has been linked to skin and eye irritations, lung damage and asthma, particularly in children. Besides accidental spills, which can be costly to clean up, chlorine can cause burns, release toxic air emissions and create persistent organic pollutants. Chlorine also is required by Maine in all public pools to sanitize the water. All public pools are required to have 2 parts per million (2 ppm) of free chlorine in the water for adequate sanitization.
DEP partnered with Water Purification Associates (a distributor of a food-grade enzyme) and the pools at the YMCA and the Clarion Hotel in Portland. The project tested use of an enzyme that is manually added to the pool and used in addition to its chlorine product.
Introduction of the enzyme reduces the amount of phosphates in the water, which allows the chlorine present in the pool to work more effectively because excessive amounts of phosphates (more than 50 parts per billion) can reduce chlorine’s overall effectiveness in the pool. Phosphates are found in some water sources naturally, but sometimes can be added to water by the water districts to prevent corrosion on municipal pipes.
The food-grade enzyme used in this project would not be as much of a benefit to pools if the phosphate levels were already low (less than 50 parts per billion). The P2 program chose the two partner pools because they both had levels of phosphates exceeding 200 ppb.
DEP managed the distribution of the enzyme to the participant pools and measured the overall reduction in chlorine used at each pool, while still allowing the vessels to meet the state-required 2 ppm of chlorine requirement. Prior to the pilot project, the Portland YMCA used 5 to 7 gallons of sodium hypochlorite per day to maintain the 2 ppm requirement. Since adding the enzyme product, it has been able to reduce usage to 2 to 3 gallons daily — about a 60 percent reduction of chlorine.
The YMCA now is saving more than $350 per month on chlorine, which is more than enough to pay the cost of the enzyme ($190/month to treat its 150,000 gallon pool). Net monthly savings, after including the cost of the enzyme, are $160 per month.
The Clarion Hotel also significantly reduced the chlorine use to treat its 30,000-gallon indoor pool. With the addition of the phosphate-controlling enzyme, the hotel reduced the amount of chlorine it was using to maintain the 2 ppm requirement by 87 percent and is saving $200 per month in chlorine, which more than covers the cost of the enzyme ($130/month to treat 30,000 gallons). Net monthly savings, including the cost of the chemical, are $70 per month.
The Clarion Hotel and the YMCA now are using significantly less chlorine to maintain the state-required 2 ppm. In addition, both pool operators experienced positive results with water quality and have observed noticeable improvements in the indoor air quality. Many swimmers have commented on the better water and air quality.
This is an excellent example of business and government working together to reduce a toxic chemical and save money.