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Water Treatment Basics

Water Treatment Basics. Brian Benham Biological Systems Engineering Virginia Master Well Owner Network Training May 30, 2009 Christiansburg, Virginia. Water treatment terms. Physical treatment Filtration Reverse Osmosis Adsorption Heating Ultraviolet light Chemical treatment

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Water Treatment Basics

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  1. Water Treatment Basics Brian Benham Biological Systems Engineering Virginia Master Well Owner Network Training May 30, 2009 Christiansburg, Virginia

  2. Water treatment terms • Physical treatment • Filtration • Reverse Osmosis • Adsorption • Heating • Ultraviolet light • Chemical treatment • Involves adding a solid liquid or gas to alter the chemistry of the treated water • Water softners, acid neutralizing filters, chlorination, ozonation • Point of use (POU) – single faucet • Point of entry (POE) – whole house

  3. Bacteria • Coliform Bacteria • Coliform bacteria are used as an indicator organism • If present, means that disease-causing organisms may also be present • E. coli bacteria are a subset of Total Coliform bacteria come from human and animal digestive systems – means that fecal matter is in the water • Iron-, Manganese- and Sulfur-reducing bacteria • Nuisance bacteria – can produce stains, odors, ‘slime’ • Not a health risk

  4. Bacteria Treatment Methods • Shock chlorination • Involves adding chlorine to the well/spring box/cistern • Relatively easy to do • Not a long-term solution – does not address source • Should be done anytime well is “opened” • Need to know depth of well and depth of water in well top of page 3

  5. Bacteria Treatment Methods • Chlorine injection • Continuous disinfection • Requires “contact” time • High maintenance http://www.cleanwaterstore.com/chlorinator.html

  6. Bacteria Treatment Methods • Ultraviolet systems (UV) • Disrupts bacteria/pathogen “life cycle” • Disadvantages • Not effective in turbid (cloudy, muddy water) • Blub housing can become coated, lessening light penetration • Bulbs wear out • No way to test effectiveness (i.e., can’t test for residual chlorine levels) • Advantages • Automatic • Low contact time • Low cost to operate • More effective than chlorine • Compact and easy to maintain • No taste or odor Graphics courtesy Mike Heatwole

  7. Bacteria Treatment Methods • Ozone systems • Inject 03 – powerful oxidant • Treat bacteria and dissolved Fe, Mn • POE 2. Off Gas Tank 3. Filtration 1. Ozone Unit Clean Water Ozone Injection Pressure Tank Well http://www.ozonepurewater.com/HowWorks.htm

  8. Bacteria Treatment Methods Gas Vent • Distillation • Boiling and condensing • Removes most dissolved constituents • Low boiling point VOCs (volitale organic compounds) may NOT be removed • Limited capacity • POU Condensing Coil Contaminated Water Coil water in coil used to condense steam Steam Vapor Heating Element Distilled water to tank May need to have carbon filter Cleaning Drain http://www.everythingyoualwayswantedtoknow.com/watertreatment/DistillationProcess.gif

  9. Hardness • Hard water contains high levels of calcium and magnesium ions • Dissolved into water during contact with limestone, other minerals • Nuisance “contaminant” • Decreased cleaning action of soaps, detergents • Scale build-up in pipes and on appliances • Reduced efficiency and lifespan of water heaters

  10. Removing Hardness • Ion exchange water softner • Calcium and magnesium ions exchanged with sodium ions • Components • Resin tank • Brine tank (recharge resin) • Softner recharge cycle should be based on water usage NOT time • Discharge and dispose of brine properly – differing opinions on discharge to septic systems • Increases salt concentration of treated water • POE – can by pass cold water Brine Tank Water Softner (resin) http://www.watervalue.com/img/5600softenerillustration.jpg Home Water Treatment, NRAES-40

  11. Adjusting pH • Raise pH with an acid neutralizing filter • Uses calcite or calcite/magnesium oxide mixture depending on pH • POE http://crystalquest.com/Acid%20Neutralizing%20water%20filter.htm http://www.cleanwaterstore.com/acid-neutralizer.html

  12. Filtration • Several types of filters • Used for a variety of constituents • Most common suspended solids (sediment) • Can remove iron and manganese if in particulate form Iron and manganese can be dissolved in water. One way to remove is to introduce an oxidizing agent (air, chlorine, ozone) then filter resulting particles • MUST match filter to target constituent(s) and integrate with other treatment components

  13. Filters: Media • Removes suspended solids • Often used as prefilter when constituents in raw water harm or reduce effectiveness of other treatment devices • “Media” can be variety of materials • Sized by pore size and flow rate • Maintenance involves periodic backwashing • POE http://www.aquaflo.co.nz/images/filters/multimedia/Multimediatankcutout.jpg

  14. Filters: Cartridge • Primarily for suspended solids • Sized by pore opening and flow rate • Maintenance involves periodically replacing cartridges • POU or POE Pleated http://www.filtersfast.com/ProdImages/rs6-lg.jpg http://www.viledon-filter.co.uk/p/liquid/Cartridge_Filter_s40.jpg “Spun or Wound” Cartridge Filter Housing, Filter, Wrench http://www.bestfilters.com/images/ProductImages/bfsf5020425.jpg http://thewaterexchange.net/wh34.jpg

  15. Filters: Cartridge Home Water treatment, NRAES-48

  16. Reverse Osmosis – RO • Effective for a variety of contaminants • Relies on pressure to force water thru a membrane • Analogous to a filter • POU http://www.water-right.com/residential/reverse_osmosis/eclipse/eclipse.html http://www.reverseosmosiscanada.com/

  17. Filtration Spectrum Human Hair Home Water treatment, NRAES-48

  18. Filters: Activated Carbon • Adsorption – contaminant binds to carbon • Honeycomb-like structure provides enormous area for contaminants to bind to • Effectiveness declines over time • Granular carbon most common in home treatment uses • POU http://upload.wikimedia.org/wikipedia/commons/2/2d/Activated_Carbon.jpg http://www.cee.vt.edu/ewr/environmental/teach/wtprimer/carbon/ccoal1.jpg http://innofresh.files.wordpress.com/2009/04/photo-activated-carbon-2.jpg

  19. Resource

  20. Home Water Quality Problems – Causes and Treatments: 356-482

  21. Water Treatment “talking points” • Treatment devices should be certified • National Sanitation Foundation (NSF International) – www.nsf.org. • Water Quality Association – www.wqa.org • Water treatment professional Training and Certification • WQA offers Certified Water Specialist (CWS) program levels 1 – 6 • WQA “Find a Member” database http://wqa.org/members.cfm?section=3 • Are others that have used service/made a purchase satisfied? What would they do differently? • Beware of scams and pressure sales pitches. • Have water tested at a certified lab. Test regularly. • Be an INFORMED consumer!!

  22. Additional Information Virginia Household Water Quality Program 540-231-9058 www.wellwater.bse.vt.edu Water Quality Association630-505-0160www.wqa.org National Sanitation Foundation 734-769-8010 www.nsf.org Water Systems Council202-625-4387 www.wellcarehotline.org National Groundwater Association 800 551.7379 www.ngwa.org Virginia Water Well Association 540-740-3329 www.vawaterwellassociation.org American Ground Water Trust603-228-5444www.agwt.org USEPA Safe Drinking Water Hotline800-426-4791www.epa.gov/safewater/hotline Virginia Department of HealthOffice of Drinking Water804-786-6278 www.vdh.state.va.us/DrinkingWater Local Health Departments-in the phone book under Government

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