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Basic Ground Water Treatment

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Presentation on theme: "Basic Ground Water Treatment"— Presentation transcript:

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 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 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
under GWR Contact Time (CT) Calculator

12 Treatment EPA CT Value Table

13 Chemical Injection Systems
4-log treatment systems must have must have redundancy or backup equipment immediately available 4-log treatment systems must have redundancy or backup equipment immediately available.

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? Parameter Maximum Limit Color 15 Iron 0.3 mg/L Manganese 0.05 mg/L Hardness 120 mg/L Hydrogen Sulfide Non-Detectable Suspended Solids 10 mg/L Turbidity 1.0 NTU

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,

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 Removal Continuous Regeneration
National Environmental Training Association, Inc., Field Guide, III-3, 1999

29 Iron/Manganese Removal Intermittent 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 Removal of iron and manganese
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 Adjustment Calcite 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 months) Minimum weekly monitoring of pH level is required to be taken, recorded, and retained under RCSA Section B102(e)(7)(N)


40 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 B102(e)(7)(N)


42 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 by the 9th day of the following month.

43 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

44 Neutralizer + Water softener + sediment filter + UV

45 Where does the backwash go?
BACK WASH DISCHARGE MUST BE AIR-GAPPED Not in the septic system (definition of domestic sewage in RCSA Section 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


47 What is wrong?

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

49 Water Treatment Equipment Chemical Feed Equipment
All chemical solution tanks (day tanks) should be equipped with tank level indicators, continuous agitators, vents to atmosphere, overlapping covers, and placed in containment basins Proper mixing and safety instructions should be available for maintenance personnel All chemical injection pumps must be controlled by an in-line flow sensor to prevent accidental overfeed in the case of a no-flow condition Chemical feed rates should be proportional to flow Injection pumps should be of the positive displacement type Chemical injection pumps are installed as near as practical to the injection point A separate chemical injection pump shall be used for each chemical applied

50 Water Treatment Equipment Chemical Feed Equipment (cont.)
Chemical injection pumps may be automatically or manually controlled, with automatic controls being designed so as to allow override by manual controls Install two chemical injection pumps Spare parts shall be available for chemical injection pumps to replace parts which are subject to wear and damage Make-up water line to the chemical solution tank must have proper backflow prevention device installed Hoses used to provide make-up water should never be left in the chemical solution tank after replenishing even if a vacuum breaker is installed on the hose bibb

51 Trivia Questions Is a backflow prevention device needed for the make up water line? YES, if no air gap exists. What NSF Standard should be applied to drinking water chemicals? NSF Standard 60

52 Classification of Water Treatment Plants and Small Water Systems

53 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”

54 “Passive Treatment” - Small Water System
Treatment unit process that does not require any chemical treatment, process adjustment or media regeneration by an operator UV Light Calcite filter – media is replaced off site by licensed professional Cartridge filter (whole house filter, sediment filter) Exchange Softener – no backwash & media is regenerated off site Granular Activated Carbon (taste & odor control)

55 Water Treatment Plant Classification Form
Points Assigned for: Population Served Water Supply Source Chemical Treatment/Addition Process Coagulation & Flocculation Process Clarification/Sedimentation Process Filtration Process Other Treatment Processes Special Processes Residuals Disposal Facility Characteristics - Instrumentation

56 Water Treatment Plant Classification Form
Add up all the points and determine which level treatment plant applies TREATMENT PLANT LEVEL Class I 30 points or less Class II points Class III points Class IV 76 points or greater Available on the Drinking Water Section website:

57 Treatment Plant Classification Activity
XYZ community public water system utilizes two wells to serve 200 people. Well withdrawal rate 8 gpm each (8,640 gpd each) Raw water quality elevated iron, manganese, color & turbidity, 5.8 pH Treatment Processes Chlorination, pH adjustment with KOH, greensand filters with potassium permanganate (KMnO4) for regeneration and intermittent backwash discharge to on-site dedicated disposal system


59 This includes the greensand filter (5 pts) and potassium permanganate (10 pts)

60 Class II treatment plant
Total 53 points Class II treatment plant Requires a Class II treatment plant operator

61 Contact Information Drinking Water Section 410 Capitol Ave, MS# 51-WAT P.O. Box Hartford, CT Phone: Emergency Phone: Fax:

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