Feedwater pretreatment is very important to maintaining the health of a reverse osmosis or nano-filtration system. Since these systems are so selective, they require feed water that is low in particulate matter. Even moderate concentrations of particulate matter can significantly foul membranes. Implementation of proper pretreatment prior to a reverse osmosis system or nano-filtration goes a long way into preserving membrane life and reducing operational and cleaning costs. Aqua Clear has a wide variety of pre-treatment equipment and designs.
Multimedia is one of the most common pretreatment methods used prior to a reverse osmosis system. Multimedia, dual media and mono-media sand filters all belong to a general class of granular media filters. Granular media filters typically contain considerable depths of coarse granular filtration media. Multimedia filters typically contain three layers of granular media which are comprised of garnet, sand and anthracite. Media filtration works by combining three primary transport mechanisms which are diffusion, sedimentation and interception.
Cartridge and Bag Filters are filters that effectively remove small colloidal particles from water prior to reaching a reverse osmosis system. These filters are generally sorted by particle removal size in microns. Cartridge filters and bag filters are implemented just prior to a reverse osmosis system and should not be relied on as a primary water preatreatment. Cartridge filters and bag filters used as a primary pretreatment method tend to clog very quickly due to their small pore sizes and would need to be replaced often, significantly increasing operational costs. In many instances, these filters act as a last resort in case of failure of upstream pretreatment equipment.
Activated carbon filters are widely used in water pretreatment. Filtering with granular activated carbon (GAC) is a proven method to remove different impurities from water. GAC is particularly effective in color removal and organic content removal. Aqua Clear Water Treatment Specialists Activated Carbon Filters can be used to remove chemicals that give objectionable odors or tastes to water such as hydrogen sulfide or chlorine.
Aqua Clear Water Treatment Specialists GAC Systems do not remove chemicals such as iron and nitrate because they are not attracted to the carbon. They need to be removed by other types of filtration. Aqua Clear Water Treatment Specialists Reverse Osmosis (RO) or green sand may be needed.
Water softening may be used to remove hardness ions such as calcium and magnesium from a feed water. Softeners are also capable of removing soluble iron and manganese from water, although this is not their primary purpose. Water softening is sometimes used as pretreatment to a reverse osmosis system to prevent hardness-based scaling.
However, antiscalants have largely replaced water softeners prior to a reverse osmosis system, due to the high costs of salts needed for softening and lack of brine disposal issues.
For more information on how we may be able to assist you contact an Aqua Clear Water Treatment Specialist today. Our staff can help identify and troubleshoot any inefficiencies that are occurring in your water treatment system to help you save on capital and operating costs.
