The first recorded large-scale use of municipal water chlorination in the United States dates back over 115 years to 1908 in Jersey City.
The city made history when it implemented a calcium hypochlorite (cal-hypo) granular solution. Within a decade, every large city in the U.S. had implemented some form of municipal water chlorination.
Granular cal-hypo solutions were soon displaced by sodium hypochlorite (bleach) and chlorine gas as the more common methods of chlorination in drinking water as they were, at that time, more controllable.
Today, cal hypo is available in erosion-tablet form. When used with a cal hypo delivery system, the chemistry offers key advantages in drinking water that include more consistent chlorine delivery, ease of transportation and shelf-life stability.
While chlorine gas is the most concentrated and least expensive of the three chlorination solutions, it comes with stringent regulations due to its hazardous classification. Potential gas leaks are also a major concern. Operators should be SCBA trained in case of a release, and two operators are required to be present when switching out a gas cylinder.
Liquid bleach degrades quickly, making strength consistency an issue. In fact, bleach starts degrading from the moment it’s manufactured, and as it ages, liquid bleach poses a risk of introducing elevated levels of chlorate and perchlorate into water. Additionally, spill concerns and corrosive fumes create safety issues, while secondary containment can be expensive and take up a lot of space.
All three solutions are viable choices for municipal drinking water applications. However, cal-hypo erosion tablets are the easiest to transport and help to improve operations and safety due to their delivery consistency when used in an erosion feeder, long shelf-life and fewer safety issues.
Cal-hypo tablet-based solutions can be used in any municipal application, but the following examples are where it has proven to be an especially good fit.
Wells – Groundwater applications are typically remote, unmanned sites, and in the event of a chlorine gas release, there isn’t typically anyone nearby to address the emergency. Meanwhile, bleach is bulky to deliver to each well, and since it doesn’t maintain its strength effectively in storage, it does not bode well for consistent ongoing chlorine delivery. Cal-hypo tablets, on average, hold their strength for a minimum of one full year when properly stored.
Booster Stations – Similar to wells, booster stations are also remote in nature and can benefit from the consistency and long shelf life that cal-hypo tablet-based systems provide. Injecting the right amount of chemical where it’s required reduces the amount of chlorine at the main treatment plant, and in turn, lowers the total amount of chlorine used. This also equates to less THM’s.
Primary Treatment Plants – Often, these sites were originally located miles outside of highly populated city areas to keep the majority of the population safe from accidental—and hazardous—chlorine gas releases. But as metropolitan areas continue to expand, businesses and residences are now closer than ever to these treatment plants. In this instance, cal-hypo tablet systems are an especially good fit.
Combined Sewer Overflow (CSO) Systems – CSOs need to combat unpredictable weather events by disinfecting pathogens at critical times and return water that is safe to protect nearby rivers and streams. These facilities must operate in a safe working environment. Cal hypo tablet-based solutions come without the need for hazmat suits or added training that come with SCBA requirements, all while providing a consistent delivery control.
Municipalities across the country are utilizing Westlake Water Solutions’ Accu-Tab Chlorination System to ensure their well sites fall within the proper chlorination range through a safe and hassle-free maintenance system (Cleaning is usually required once per year).
Westlake Accu-Tab SI cal-hypo erosion-tablets are packaged in 60-pound pails compared to 150-pound gas cylinders or 575-pound drums of bleach. These NSF/ANSI Standard 60 certified tablets, along with the Accu-Tab NSF/ANSI Standard 61 certified chlorination system, deliver a more neutral pH level (~9) with no spill containment necessary, and more precise and consistent chlorination control.
Learn more about how Westlake Water Solutions is increasing chlorine control, and enhancing safety at municipal water plants across the country.
J. Gary Miller is a Sr. Account Executive with Westlake Water Solutions. He has over 30 years of experience working with applications utilizing calcium-hypochlorite.