Water Treatment Basics Brian Benham Biological Systems Engineering

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 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

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

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

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

Bacteria Treatment Methods Ultraviolet systems (UV) Disrupts bacteria/pathogen “life cycle” Advantages • Automatic • Low contact time • Low cost to operate • More effective than chlorine • Compact and easy to maintain • No taste or odor 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) Graphics courtesy Mike Heatwole

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

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

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 Hardness Rating Grains per Gallon mg/L Soft Less than 1. 0 Less than 17. 1 Slightly Hard 1. 0 -3. 5 17. 1 -60 Moderately Hard 3. 5 -7. 0 60 -120 Hard 7. 0 -10. 5 120 -180 Very Hard Over 10. 5 Over 180

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 Brine Tank treated water POE – can by pass cold water Water Softner (resin) http: //www. watervalue. com/img/5600 softenerillustration. jpg Home Water Treatment, NRAES-40

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

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

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

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/Prod. Images/rs 6 -lg. jpg http: //www. viledon-filter. co. uk/p/liquid/Cartridge_Filter_s 40. jpg “Spun or Wound” Cartridge Filter Housing, Filter, Wrench http: //thewaterexchange. net/wh 34. jpg http: //www. bestfilters. com/images/Product. Images/bfsf 5020425. jpg

Filters: Cartridge Home Water treatment, NRAES-48

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. reverseosmosiscanada. com/ http: //www. water-right. com/residential/reverse_osmosis/eclipse. html

Filtration Spectrum Human Hair Home Water treatment, NRAES-48

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

Resource

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

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!!

Additional Information Virginia Household Water Quality Program 540 -231 -9058 www. wellwater. bse. vt. edu Virginia Water Well Association 540 -740 -3329 www. vawaterwellassociation. org Water Quality Association 630 -505 -0160 www. wqa. org American Ground Water Trust 603 -228 -5444 www. agwt. org National Sanitation Foundation 734 -769 -8010 www. nsf. org USEPA Safe Drinking Water Hotline 800 -426 -4791 www. epa. gov/safewater/hotline Water Systems Council 202 -625 -4387 www. wellcarehotline. org National Groundwater Association 800 551. 7379 www. ngwa. org Virginia Department of Health Office of Drinking Water 804 -786 -6278 www. vdh. state. va. us/Drinking. Water Local Health Departments -in the phone book under Government