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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