Water Technology - Jan 2012

FEATURE The effects of hard water on reverse osmosis filtration systems Pretreatment can be the best way to avoid hard water problems 24 Water Technology January 2012 Ion exchange is commonly used to soften water During ion exchange hard water is passed through a cylinder filled with resin beads that have been saturated with sodium When this happens the hardness ions are attracted to the resin and the sodium ions are released Fox adds that softening and ion exchange are used for the removal of hardness ions and that RO can be effective as well but not if youre trying to protect its membrane Going green One of the major downfalls of having hard water and its effects on a RO system is that it is not very energy efficient The minerals that clog the RO and cause scaling make the RO unit work even harder waste water and run up the utility bill There are ways to prevent this from happening and in return help the environment The amount of water thats wasted the discharge issues that were facing all over this country and really all over the world have become serious enough that the water treatment industry is paying attention to the need to reduce discharge save water and be more environmentally friendly asserts Fox I would like to see more of a focus on the need to become more efficient on the waste specifically hopefully eliminating any chemical discharge in the widespread use of reverse osmosis There is little doubt that RO has been an effective filtration technology for several decades While it does have its waste and energy drawbacks there are fewer more efficient and practical innovations available at this time for residential and light commercial use As companies continue to go green with solutions for hard water and scale reduction the focus will become more conscious of end users the environment and the bottom line WT Reverse osmosis RO can be one of the best ways to treat water for residential and light commercial facilities But there can be issues that exist after a RO unit is installed One issue that arises is the challenges presented with hard water During the filtration process hard water can cause scale making it extremely difficult for ROs membrane to work and the result is lower quality of water Hard water is the result of having high mineral content usually calcium and magnesium ions The dissolved rock causes scale which has been found to impede appliance performance and result in energy inefficiencies and increased utility costs Hardness can cause scaling of the membrane which over time will defeat the whole purpose explains Steve Fox of NEXT Filtration Technologies Inc It will reduce the output of the membrane itself and it will reduce the quality of water that the membrane is putting out Essentially it slowly kills the membrane Replacing membranes too frequently can be expensive over time Dealers should therefore seek the foundation of the issue for answers Also sharing this valuable information with customers is key According to Pam McDowell of Scalewatcher its the sticky calcium molecules that affect a RO system Calcium in the water is like cholesterol in your blood stream notes McDowell It sticks to everything binds hardens and thickens as more collects On a RO membrane the calcium molecules block the membrane making backwashing necessary on a regular basis While McDowell goes on to say that it is necessary to replace the membranes of an RO system from time to time its the dealers job to provide customers with a system that will last as long as possible How to reduce water hardness before RO Testing is the best way to deal with water hardness before installation RO systems are designed to create a lot of pressure to a certain solution to separate out heavy minerals Knowing what types of minerals are in the water can help when installing a system As with any water treatment system following the manufacturers installation is the most important part of the installation notes McDowell The second important part is knowing your water If you know that you have a specific issue such as iron an iron filtration system should be installed in tandem with the RO After installation its always best to continue to monitor the water to make sure scaling isnt becoming a major problem in the RO system If you are changing the membranes of your RO system quite frequently McDowell suggest that it may be time to find another system and or hardness solution Carbon filters may be used to remove chlorine which can have a negative effect on TFC thin film composite and TFM thin film material membranes notes Jan de Baat Doelman president of Scalewatcher Carbon pre filters are not used if the RO system contains a CTA cellulose tri acetate membrane By Jake Mastroianni Assistant Editor For more information on this topic go to www watertechonline com and enter keyword s Reverse osmosis hard water softening membrane