By Greg Reyneke, MWS
As winter approaches in the north, we anticipate the sights and smells of the holiday season that is celebrated by many cultures and traditions as a time to slow down, exchange gifts, appreciate family and friends, and reflect on the year to come. Winter also allows for nature’s cycle to redirect thermal energy; it replenishes snow pack reserves, slows algae growth, inactivates certain bacteria. For the northern water treatment industry, cold weather presents many challenges, complications and opportunities.
Water temperature has a dramatic effect on the capacity and functionality of many water treatment processes and equipment. It is important to understand the influence of ambient temperature and water temperature on the effectiveness and longevity of the water quality improvement systems that you sell, install and maintain.
As a covalently bonded hydrogen compound, water behaves uniquely when temperatures drop. As it cools, water’s density tends to increase until it reaches the anomalous expansion range of 4° to 0°C (39.2° to 32°F), at which point its density will decrease. This unique behavior gives ice its ability to float, which prevents lakes from freezing solid and of course, allows for water to burst plumbing pipes and potentially wreak havoc on water treatment devices, as well as potentially changing the fundamental characteristics of a water.
Gases like carbon dioxide (CO2) dissolve more readily as the temperature drops, so more gas will be retained in colder water. This can lead to an increase in visual bubbles/cloudiness, cavitation and possibly even a drop in pH, which could lead to increased potential for corrosion.
Since water typically increases in density before reaching the anomalous expansion range, membrane flux in reverse osmosis, nanofiltration and ultrafiltration systems will decrease significantly as water temperatures drop. Be sure to make the appropriate adjustments and compensations recommended by the equipment manufacturer to deliver the maximum amount of permeate without causing premature equipment failure.
Problem water filters
Cold water typically results in increased contact time being required for reactive media to be effective. Bear this in mind when designing for applications where the water temperature will be cooler than 50°F (10°C). Each media behaves differently (especially with other complicating factors like TDS, COD, TSS, etc.). Be sure to consult with your vendor on exact criteria, but the simple rule of thumb is: “The colder it gets, the slower it gets.”
Increasing water density means that less backwash flowrate is required to lift the media in a tank. Consult with your distributor about designing equipment with sufficient freeboard and appropriately sized backwash flow controls to ensure that no media is lost from the system.
Cold water slows ion exchange kinetics significantly and increases salt dissolution times. Slow kinetics cause a significant decrease in effective system capacities, which usually causes customers to end up with hard-water bleed-through, unless the dealer makes appropriate programming compensations. High-speed resins, upflow regeneration and resin exhaustion sensors are good ways to help minimize this issue. Many dealers will reduce the typical system capacity by as much as 30 percent when it will be exposed to cold influent water in the range of 35°F to 45°F (1.6° to 7.2°C).
Winterization procedure for water softeners
There are many opinions on how to winterize water softeners. Some dealers believe that, since most softeners installed in cold climates are installed in basements, they require no winterization. I believed that until I witnessed ambient temperatures in Montana basements hovering at -10°F (-23°C) during January in unoccupied vacation homes. These low ambient temperatures, along with resultant ice expansion, will cause a fiberglass resin tank to split as if they were opened by a zipper. Not a healthy situation when things finally thaw out in spring.
Winterization is normally only performed when the home/business will be unoccupied and marginally heated during winter. A simple and generally safe, effective single-tank water softener winterization procedure is as follows:
- Initiate a manual regeneration cycle.
- Advance manually to the brine/rinse ion exchange cycle.
- Induce a brine solution into the softener along with resin cleaner and disinfectant into the mineral tank (five gallons of saturated brine per cubic foot of resin is typical).
- Bypass the system and terminate the regeneration cycle.
If the building will be unheated and piping blown-out or drained down, the following additional steps should be performed instead of bypassing the system:
- Inject compressed air through the brine port at a maximum of 20 psi until all brine has been purged from the resin tank down the drain.
- Advance through each remaining regeneration step to allow water to drain from the control head.
- Leave system in service (do not bypass).
- Disconnect and remove the float from the brine tank; drain and store in a safe place.
- Drain down or blow down the plumbing system as per normal winterization procedures.
Some dealers perform winterization by introducing antifreeze into the mineral tank with a pump. When using antifreeze, be careful to use only propylene glycol (food-grade) antifreeze. Ethylene glycol antifreeze is highly toxic and should never be used for winterization. Springtime startup procedures should include a rigid disinfection and rinsing protocol to provide for the health and safety of the establishment and its occupants.
Winter driving and work-zone safety guidelines
Being in a work truck doesn’t automatically make you safer; in fact, it typically impairs your visibility and mobility. Here are some good guidelines:
- Check battery, tire tread and windshield wipers, keep your windows clear, put no-freeze fluid in the washer reservoir, check your antifreeze level and change the vehicle’s oil.
- Keep emergency supplies in the vehicle, like a flashlight, jumper cables, abrasive material (sand, kitty litter), folding shovel, snow brush and ice scraper, road flares, blankets, food and water.
- Practice cold-weather driving in a safe area when your neighborhood gets snow and understand how the vehicle handles in snowy conditions.
- Check to see that windows and mirrors are clean of ice and debris before driving.
- Drive with your headlights on.
- Put your cellphone down!
- Keep both hands on the wheel.
- Know what kind of brakes your vehicle has and how to use them properly. In general, if you have anti-lock brakes, apply firm, continuous pressure. If you don’t have anti-lock brakes, pump the brakes gently to stop.
- If you ever do find yourself in a skid, stay calm and ease your foot off the gas while carefully steering in the direction you want the front of your vehicle to go. Stay off the pedals (gas and brake) until you can regain control of your vehicle. This procedure, known as steering into the skid, will bring the back end of your car in line with the front safely.
When working in the field and on job sites, remember that cold weather makes your hands less sensitive and your body move more slowly. Consider the following:
- Cover your head to conserve body heat.
- Layer your clothing. Multiple layers of light clothing allow you to adjust protection based on current temperature. Take off layers as you get warm and put them on as it gets colder.
- Keep a change of clothes, socks and footwear on hand, in case you get wet. Dry clothing helps to keep you warm.
- Even though it’s cold out, keep hydrated by drinking water or warm drinks. You will still lose body moisture when working, even at those cold temperatures. Avoid excessive caffeine and alcohol.
- To avoid slipping on ice, wear winter boots with a strong tread. Spread sand or rock salt on the ice to provide a rough surface for footwear to grip.
- Carry winter-appropriate shoe covers to use when working inside a client’s home or business.
Be smart, sensible and thoughtful in your approach to working through winter so that you and your team remain safe while providing your clients with the very best water quality and customer service.
Greg Reyneke, Managing Director at Red Fox Advisors, has two decades of experience in the management and growth of water treatment dealerships. His expertise spans the gamut of residential, commercial and industrial applications, including wastewater treatment. In addition, Reyneke consults on water conservation and reuse methods, including rainwater harvesting, aquatic ecosystems, greywater reuse and water-efficient design. He is a member of the WC&P Technical Review Committee and currently serves on the PWQA Board of Directors, chairing the Technical and Education Committee. You can follow him on his blog at www.gregknowswater.com