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Basic Ground Water Treatment

Basic Ground Water Treatment. Cindy Sek Sanitary Engineer 2 DPH - Drinking Water Section Compliance Regions - North. Topics of Discussion. Why is water treatment used? ANSI/NSF Standards Considerations before installing treatment Disinfection Organics removal

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Basic Ground Water Treatment

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  1. Basic Ground Water Treatment Cindy Sek Sanitary Engineer 2 DPH - Drinking Water Section Compliance Regions - North

  2. Topics of Discussion • Why is water treatment used? • ANSI/NSF Standards • Considerations before installing treatment • Disinfection • Organics removal • Iron and manganese removal • Corrosion control treatment • Treatment systems in combination • General Water Treatment Guidelines • Classification of Water Treatment Plants

  3. Why is Water Treatment Used? • To remove contaminants and achieve compliance with a Maximum Contaminant Level (MCL) thereby reducing health risk • Disinfection to kill or inactivate total coliform and/or E.coli bacteria and associated microbial pathogens • Organics removal with Granular Activated Carbon (GAC)

  4. Why is Water Treatment Used? • To achieve aesthetic water quality standards • Sediment filters to remove suspended particles • Ion exchange water softener • Iron and manganese filtration • Taste and odor control using Granular Activated Carbon (GAC)

  5. Why is Water Treatment Used? • For corrosion control • Calcite filtration for pH adjustment • Chemical injection for pH adjustment • Orthophosphate for sequestering

  6. ANSI/NSF Standard 60 & 61 • All drinking water treatment chemicals and components must be certified to ANSI/NSF standards. • NSF/ANSI Standard 60: Drinking Water Treatment Chemicals - Health Effects is the nationally recognized health effects standard for chemicals which are used to treat drinking water. • NSF/ANSI Standard 61: Drinking Water System Components - Health Effects is the nationally recognized health effects standard for all devices, components and materials which contact drinking water.

  7. Other ANSI/NSF Standards • NSF/ANSI Standard 42: Drinking Water Treatment Units - Aesthetic Effects • NSF/ANSI Standard 44: Cation Exchange Water Softeners • NSF/ANSI Standard 53: Drinking Water Treatment Units - Health Effects • NSF/ANSI Standard 55: Ultraviolet Microbiological Water Treatment Systems • NSF/ANSI Standard 58: Reverse Osmosis Drinking Water Treatment Systems • Visit www.nsf.org for more information

  8. Considerations Before Installing Treatment • Type and concentration(s) of contaminant(s) • Treatment options • NSF Certification • Initial cost of installing treatment equipment and ongoing costs of maintenance, chemicals, and additional water quality testing • Available room to install treatment in existing pump house • Submittal to DPH for review and approval prior to installation per RCSA Section 19-13-B102(d)(2) • Water treatment plant operator to maintain and operate the treatment system • Staff certified at the appropriate level • Contracting with a certified treatment plant operator

  9. Chemical Disinfection • Chlorination is used to inactivate bacteria and/or viruses that may be introduced into the water system • Correct well violations and deficiencies first • Eliminate cross connections within system piping first • Use alternate source of supply • GWR requires maintaining 4-log virus treatment • Source with significant deficiency or fecal contamination • Exempt from GWR source water monitoring requirement • Existing treatment systems need to demonstrate that treatment meets this level • A CT value of about 6 is necessary to achieve this level • Routine compliance monitoring is required to ensure that treatment is effective and public health is protected.

  10. Compliance Monitoring • Chlorine Compliance monitoring • >3,300 population – continuous monitoring at a location at least equivalent to 1st customer. • <3,300 population – continuous monitoring at a location equivalent to 1st customer or 1 grab sample/day at the time of peak hourly flow.

  11. http://www.epa.gov/safewater/disinfection/gwr/compliancehelp.html under GWR Contact Time (CT) Calculator

  12. Treatment EPA CT Value Table

  13. Chemical Injection Systems 4-log treatment systems must have redundancy or backupequipmentimmediatelyavailable.

  14. Chlorination Systems Advantages • Destroy bacteria, viruses, and other pathogenic microorganism, except Giardia and Cryptosporidium • Provide a barrier of protection throughout the water system when an adequate chlorine residual is maintained • Disinfectant residual can be monitored • Can be used as an oxidant to suspend metals in solution for better filtration treatment performance • Oxidizes hydrogen sulfide to reduce nuisance odor

  15. Chlorination Systems Disadvantages • More maintenance • Chemical addition and disinfection by-products • Need to maintain adequate contact time for effective disinfection • Need to monitored on a daily basis • Requires a higher certified operator skill level • More space required for contact tank and treatment system • Mineral oxidation may necessitate the need to install filtration treatment if raw water has mineral content. • Iron and/or Manganese common in groundwater

  16. Trivia Questions • The GWR requires what level of treatment at the entry point for effective virus inactivation / removal? 4-log • Can I continue to use my existing disinfection treatment if it does not meet 4-log virus inactivation / removal? Yes, however please note assessment or triggered source water monitoring may be required.

  17. Ultraviolet Disinfection • May be considered for approval as a primary disinfection treatment if UV treatment guidelines are met • Source of supply is groundwater • Bacteria (total coliform) is documented to be coming from the groundwater source (not in distribution system) • UV unit meets ANSI/NSF 55 Standards • Raw water meets prerequisite water quality data • Iron and Manganese, color, turbidity • Suspended solid, hardness, hydrogen sulfide

  18. Ultraviolet Disinfection Advantages • No chemicals • Instantaneous bacteria inactivation • Closed system • No disinfection by-products • Low maintenance • Can be installed in a relatively small space if pre-treatment is not necessary • Relatively low initial and maintenance costs compared to chlorination systems

  19. Ultraviolet Disinfection Disadvantages • No disinfectant residual. • Currently, no known single low pressure UV units will provide 4-log inactivation/removal of viruses. • Require for assessment monitoring per GWR. • Will only be effective if the bacteria source is entering the water system prior to the UV unit. • Pretreatment may be necessary for raw water with moderate to high mineral content. • May require units to be installed in parallel if water system cannot be shut down to allow for UV maintenance or replacement.

  20. Ultraviolet Disinfection

  21. Ultraviolet Disinfection

  22. Trivia Question • What are some of the raw water minerals to be concerned of when considering a UV treatment system?

  23. Trivia Question • What are some of the raw water minerals to be concerned of when considering a UV treatment system?

  24. Granular Activated Carbon (GAC) • Absorbs Organic Chemicals • gasoline, benzene, toluene • DDT, PCB, etc. • Controls taste & odor • Chlorine smell • Sulfur odor (rotten egg smell) • Typically 2 units are installed in series for organic removal

  25. Multiple GAC units for VOC removal

  26. Aeration (Air Stripping) Multi-Staged Bubble System • VOC • Radon • TTHM • Hydrogen Sulfide • Iron Oxidation • pH Adjustment Lowry Deep Bubble Air Stripper, www.lowryh2o.com

  27. Iron/Manganese Removal • Filtration is typically combined with pre-oxidation • Media: Manganese Greensand, Birm, Multimedia • Regeneration / Oxidation: Potassium permanganate • Oxidation: Chlorine, Air injection • Manganese is typically oxidized at a higher pH therefore pH adjustment may be required • Phosphate – sequestering iron • Water softeners • Best for Ferrous Iron < 5 mg/L

  28. Iron/Manganese RemovalContinuous Regeneration National Environmental Training Association, Inc., Field Guide, III-3, 1999

  29. Iron/Manganese RemovalIntermittent Regeneration National Environmental Training Association, Inc.,Field Guide, III-3, 1999

  30. Multiple Greensand Filters with GAC

  31. Trivia Question • What is the purpose of air injection or aeration in the treatment process? • Oxidation • VOC removal • Radon removal • pH adjustment

  32. Water Softeners • Removal of hardness • Calcium and/or Magnesium • Removal of iron and manganese • Regenerate with sodium chloride or potassium chloride • If sodium levels are already elevated, potassium chloride may be preferable • Sodium notification level is 28 mg/L

  33. Ion Exchange Softening National Environmental Training Association, Inc.,Field Guide, III-6, 1999

  34. Cartridge Sediment Filters • Remove silt, sediment, and other suspended matter • Use as pre-filter for other treatment processes • Sediment filter should be changed on a regular basis • Spare filters should be kept in their original wrappings • Add a tablespoon of bleach to filter housing after filter replacement

  35. Trivia Questions • What is one of the functions of a water softener in a treatment process? -- Hardness removal -- Iron and Manganese removal • Should a cartridge filter be used for bacteria removal? No

  36. Corrosion Control • pH adjustment • Calcite Filter • Chemical injection • Introduction of corrosion control inhibitors • Calcite filters - protect scaling in pipes • Phosphate chemical injection - applies a protective layer on the pipes to help prevent corrosion

  37. Corrosion Control • Evaluate source Water Quality Parameters (WQP) results • WQP – pH, alkalinity, calcium, conductivity, phosphate, temperature • Based on results, determine the most effective treatment system • After installation of treatment, check WQP and saturation index at entry point to confirm treatment effectiveness

  38. pH AdjustmentCalcite Filters • A.K.A. acid neutralizers or limestone contactors • Raise pH (typically not beyond 7.5) • Add hardness (calcium carbonate) and alkalinity which can be beneficial for corrosion control • Replace filter media periodically (i.e. 6-12 months) • Minimum weekly monitoring of pH level is required to be taken, recorded, and retained under RCSA Section 19-13-B102(e)(7)(N)

  39. Chemical Injection • pH adjustment with potassium carbonate, sodium carbonate (soda ash), or hydroxide products • Allow a wider range of pH level to be achieved • More hazardous than a calcite filter • Potential for chemical overfeed if chemical injection safety controls are not installed • Recommend injection paced proportionate to flow • Sequestering with phosphate • Daily monitoring of pH level or biweekly monitoring of phosphate level is required to be taken, recorded, and retained under RCSA Section 19-13-B102(e)(7)(N)

  40. Trivia Question • What is the monitoring requirement for the pH adjustment process? -- Calcite Filters - at least weekly pH readings -- Chemical injection – Daily pH readings The readings must be recorded on the Treatment Effluent Log and submitted to drinking.water@ct.gov by the 9th day of the following month.

  41. Treatment Systems in Combination • Calcite followed by a water softener • Used to remove iron and manganese • Calcite raises pH and facilitates manganese removal with the water softener • Calcite adds hardness and water softener reduces hardness • Water softener followed by UV Treatment • Water softener reduces hardness, iron and manganese • Bacteria passing through UV unit is inactivated and does not “hide” under larger minerals • Many other possible combinations

  42. Neutralizer + Water softener + sediment filter + UV

  43. Where does the backwash go? • BACK WASH DISCHARGE MUST BE AIR-GAPPED • Not in the septic system (definition of domestic sewage in RCSA Section 19-13-B103 excludes treatment backwash) • Dedicated on-site water treatment disposal system or sanitary sewer (Draft DEEP General Permit for the Discharge of Low Flow Water Treatment Wastewater) • Must meet separating distance to well • Must be at least 10 ft from existing septic system • DEEP General Permit may be required • Backwash discharge > 500 GPD

  44. What is wrong?

  45. What is wrong? No air gap for BW discharges No air gap for BW discharges & storage tank drain

  46. Classification of Water Treatment Plants and Small Water Systems

  47. Small Water Systems • If the CPWS or NTNC serves less than 1,000 persons and either has no treatment or a treatment unit process that does not require any chemical treatment, process adjustment or media regeneration by an operator then the system is classified as a “SMALL WATER SYSTEM”

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