Ohio Water Plant Finds Effective Alternative To Chlorine Gas

Two successful pilot studies prompt Ohio EPA to approve Constant Chlor ® calcium hypochlorite system for Huber Heights.

 

For many years, Huber Heights, Ohio, had searched for an effective and affordable way to eliminate gaseous chlorine (Cl 2 ) use at its 4.46 MGD Needmore Road Water Treatment Plant. Earlier this year the plant’s gas chlorination equipment and pressurized gas cylinders were finally removed from the site. In their place, but encompassing a much smaller footprint, now sits the innovative dry calcium hypochlo - rite makeup and delivery system that made this change possible.

Background

Drinking water to Huber Heights and Miami County customers is supplied from two water treatment plants, the Needmore Road Water Treatment Plant and the 7 MGD Rip Rap Road Water Treatment Plant.

“When the new Rip Rap Road plant came on line in 2006, we set up our Needmore plant to serve as our back-up facility,” says former Huber Heights Engineer and now Assistant City Manager, Scott Falkowski. “The plant typically runs two times a week for a couple of hours, to keep its clear wells and equipment turned over. Last year, one of our wells went down and we had to run the old plant full time for a while, so it’s still very important for us to maintain its full operability.” As the old plant remained active, it still retained a lot of the old ways of doing things, including chlorina - tion. The continued operation of the gas chlorination system at the Huber Heights plant proved troubling, according to Pam Whited, Project Manager for United Water Envi - ronmental Services, the private firm contracted to operate and manage the city-owned Division of Water and Wastewater under a long-term public-private partnership with Hu - ber Heights. “We and the city wanted to get away from using chlorine gas at the plant, primarily for health and public safety reasons,” she says. “But it was difficult to find a viable, cost effec - tive alternative. We looked closely at sodium hypochlorite, but ultimately realized it wasn’t going to work.” One challenge to using NaOCl, according to Whited, would be its relatively short storage life. “Because we operate the plant only two hours a day, two days a week, any sodium hypochlorie stored there would lose much of its strength before we could use it.” Sodium hypochlorite can begin to show degradation

in less than 30 days of delivery and loses strength faster at higher temperatures. “Plus, the plant did not have the necessary containment systems to legally store bulk sodium hypochlorite on site, and the cost would be phe - nomenal to build the required containment there,” Whited says. Plant operators were also anxious to eliminate the use of chlorine gas at the site. “We always had to have two people to change out the tanks – one to change the cylinders and one to stand outside and be ready in case some - thing happened,” Plant Operator Jeffrey Van Meter says. “Also, we had to rebuild the gas equip - ment each year ourselves. We couldn’t contract out the work because no one else would take the liability.” Pilot Study In a bit of fortuitous timing, Environmental Ser - vices learned that Arch Chemicals, Inc., a Lonza company, was planning to conduct a pilot study of its Constant Chlor ® dry calcium hypochlorite briquettes and engineered feed system in Ohio. The system is approved in most states, including Wisconsin and Illi - nois, but had not yet been approved in Ohio. “We had the opportunity to use the calcium hypochlorite system dur - ing the pilot study to see if it would work for us, and indeed it does,” Whited says. “The first pilot started in early 2012, and the state EPA ultimately required that Arch conduct two studies.”

 

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