By Peter Chawaga, Associate Editor, Water Online
As most of us enjoy the improved weather brought on by winter’s transition into spring, many water treatment operations are still recovering from a lesser-known downside of the changing seasons. As snow and ice melt, they inundate water systems with runoff and contaminants.
“Ice melt brings additional solids into the water through soil erosion, which occurs during the water runoff,” said Ronald Thomas, an industrial sales manager at Pall Water. “Constituents vary by geography, but most common are particulate soils, minerals, organics, and trace metals.”
It is not uncommon, added Thomas, for water analysis following ice melt to show increased nephelometric turbidity units (NTU) and total suspended solids (TSS), indicating a need to increase pre-filtration and filtration system performance for this relatively short window of time. Most treatment technologies will perform erratically when TSS increases, producing lower-quality water.
To help treatment plants protect against increased solids inundation during ice melt, Pall Water introduced a mobile filtration trailer that can be installed on-site when needed to keep water quality normal. They utilize a 0.1 micron membrane system, acting as a barrier between the treatment technology and solids brought in by extra runoff.
“Essentially, suspended solids are eliminated from passage through the membrane and the filtrate water can be used for process or reverse osmosis feedwater,” Thomas said. “Trailers are rated at 1 MGD of processed filtrate water.”
The system is essentially a Pall Aria microfiltration membrane living inside of a 48’ x 53’ trailer, to which a system can hook up its source water, effluent pipe, and power. As for the cost, that will depend on specific needs.
“It varies as a result of flow rates, chemistry, length of operation, and discharge costs,” said Thomas. “The best way to determine costs is to walk through a use-cost calculator exercise with the operator. Inputs on plant specifics are entered and the costs are calculated immediately.”
To convince operations of a positive return on their investment, Pall Water will help operators calculate the cost that ice melt brings to their operations and compare that to the costs of operating the mobile filtration trailer. Then it will be a simple matter of deciding whether or not the upfront cost will be worth it in the long run.
Of course, it isn’t just annual ice melt that makes mobile filtration an attractive option.
“Any change in the hydrological cycle can impact influent water quality,” Thomas said. “Flooding, hurricanes, heavy rain events, dredging, and drought all create challenges for water plant operations. Knowing what tools are available, who to call, and preparation are very important in managing these types of situations.”
And water utilities aren’t the only prospective customers. In some cases, industrial treatment operations should consider investing in the trailers as well.
“Industrial users have very similar challenges as utilities,” said Thomas. “Most generate steam or supply water. The water requirements for low-pressure, high-pressure boilers and process water are universal.”
If an operation decides the solution is a right fit for them, there are some options available for optimizing it.
“The trailers operate on variable frequency drives and programmed logic controllers, which allow the operator to vary flow rates depending on needs,” Thomas said. “For larger applications, multiple trailers can be deployed in parallel to support the operation.”
It’s a solution that can make the most of spring’s sunny skies.
Image credit: "Melt," Will's Photos, Canada © 2017, used under an Attribution 2.0 Generic license: https://creativecommons.org/licenses/by/2.0/