Recently enacted arsenic compliance standards have forced cities large and small to comply with a maximum contaminant level of 10 parts per billion (ppb) or face stiff fines and even the potential shutdown of wells. Smaller towns such as Cannonville, UT, have the most difficulty meeting those standards because of manpower and budget constraints.
To help meet the standard, Cannonville turned to Filtronics Inc. of Anaheim, CA, and its proprietary arsenic removal process.
Filtronics provides systems that can process up to 29 mgd, but it was one of the company’s more compact FV series vertical filters - equipped with Electromedia® I - that helped Cannonville and its population of just 200 people. Located near Bryce Canyon National Park, Cannonville is a small community with an understandably small public-service budget.
“We looked at some other ways to remove arsenic,” said Mayor Al Fletcher, “but disposal was costly.”
The city found that the initial cost of the Filtronics plant was competitive with other systems on the market, but because the company’s filter media is permanent, operation and maintenance costs are lower than that of many other arsenic removal methods. Some filter systems, for example, are expensive to run: the media itself is costly, and when exhausted, must be replaced. And if the used media - contaminated with a high concentration of arsenic - isn’t handled properly, it is considered hazardous waste.
There are no such worries with Filtronics Electromedia® I.
The granular media accommodates a 10 gpm/sq. ft. flow rate, and the backwash to filtration ratio is less than 2 percent. Because the arsenic is removed from the media more frequently and in lower concentrations, it can be disposed of in a sanitary sewer, or the sludge can be collected and sent to a sanitary landfill.
Treatment for Cannonville has been successful, particularly in light of the fact that the city’s well also has a high concentration of iron in the raw water. Removal of iron is also a common application for Electromedia® I.
“We have a 1300 foot deep well and pump about 300 gpm,” said part-time plant manager Larry Fletcher, who is also the mayor’s brother. “Arsenic in the raw water is about 40-45 ppb, which is reduced essentially to zero with the filter. But there is also a lot of iron - it’s not very nice water. Treatment is kind of a two-prong approach, because it takes out the iron.”
In terms of maintenance, the system has also proven successful, needing very little attention since its 2003 installation.
“I check on the system once per day, but it pretty much takes care of itself,” said Larry Fletcher.
