CAMPBELL, CA, July 21, 2009 -- Nearly 60,000 people in Pine Bluff, Ark., as well as the regional hospital that serves five times that population, depend on United Water Arkansas for clean, reliable water when they turn on the tap.
But in the event of a natural disaster or flu outbreak, who would United Water Arkansas (UWA) rely on?
Any interruptions in shipments of bulk commercial sodium hypochlorite would disrupt operations at the company's three treatment plants, possibly leaving the state's fourth-largest hospital in the lurch. This situation left UWA managers facing the question of how to ensure a reliable supply of water to their customers during a flu pandemic or other emergency situation.
Utilizing Department of Homeland Security guidelines, they developed a Continuity of Operations Plan allowing the utility to function during a health crisis or other disaster. Part of the plan was to upgrade to a more resilient disinfection system at Treatment Plant #2 to prevent a supply-related interruption in service.
Their answer was the MicrOclor Onsite Hypochlorite Generator, manufactured by Process Solutions Inc. (PSI), which produces sodium hypochlorite on demand through an innovative process combining salt, water and electricity.
UWA chose the MicrOclor system because it provides greater flexibility than bulk sodium hypochlorite and is easier to install and operate than competing designs, said Shane Drye, production supervisor for the company.
"Being able to run three to four months on a single load of salt, as opposed to relying on a trucking firm for hypochlorite delivery every two weeks during peak demand, was the main reason," he said.
In addition to fewer deliveries, utilities benefit from the fact that salt is intrinsically safe and inert. Salt is an ideal raw material because it will last for an indefinite time without degradation, unlike sodium hypochlorite, which is a reactive chemical and can degrade significantly if stored in a warm climate for an extended period.
UWA's MicrOclor system is sized to meet the requirements of Treatment Plant #2, a 6.5 MGD filtration plant serving the hospital and about half the company's residential customers. It can produce up to 300 pounds of chlorine per day, and is certified by NSF to NSF/ANSI Standard 61.
MicrOclor's unique vertical electrolytic cell design also bolsters the safety of operation and the ease of maintenance, Drye said. Vertically-aligned low-pressure cells each have a recirculation loop that allows instantaneous passive removal of all hydrogen produced during the generation process, improving safety of operation and eliminating the possibility of pressurizing hydrogen in the electrolytic cell.
The unit has also produced a substantial cost savings versus the bulk sodium hypochlorite system the company installed in 1999 to meet federal environmental requirements.
"After you figure in the cost of the salt and the maintenance, MicrOclor is about half the cost we were paying for commercial hypochlorite," Drye said.
MicrOclor's skid-mounted design and small footprint allowed the unit to be owner-installed in an existing space previously used for chemical storage. A two-man UWA team installed the complete system using detailed installation drawings and technical support provided by PSI.
"Within 30 minutes we were making bleach," Drye said. "The start-up was very smooth."
"As a result of the in-house installation, our operators are more familiar with the equipment and better understand its operation and maintenance," said engineer Mamun Yusuf.
MicrOclor controls easily integrate with the plant control system, and the color touch-screen operator interface includes a context-sensitive help screen to expedite troubleshooting. The design further eliminates operator errors through a diagnostic routine that halts hypochlorite generation in the event of sensor failure or electrical bypass.
UWA reports few problems with the MicrOclor unit. Customer service from PSI has been within the 24-hour guaranteed response time, Yusuf said. When a brine pump on the unit malfunctioned, a PSI technician provided immediate troubleshooting assistance to get the system back in-service.
A replacement pump was delivered within 12 hours.
"I would say as far as customer service they were very prompt," Yusuf said. "We are happy with the system. We have been running it for two years and it works fine."