Presentation on theme: "Basic Ground Water Treatment"— Presentation transcript:
1 Basic Ground Water Treatment Cindy SekSanitary Engineer 2DPH - Drinking Water SectionCompliance Regions - North
2 Topics of Discussion Why is water treatment used? ANSI/NSF Standards Considerations before installing treatmentDisinfectionOrganics removalIron and manganese removalCorrosion control treatmentTreatment systems in combinationGeneral Water Treatment GuidelinesClassification 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 riskDisinfection to kill or inactivate total coliform and/or E.coli bacteria and associated microbial pathogensOrganics removal with Granular Activated Carbon (GAC)
4 Why is Water Treatment Used? To achieve aesthetic water quality standardsSediment filters to remove suspended particlesIon exchange water softenerIron and manganese filtrationTaste and odor control using Granular Activated Carbon (GAC)
5 Why is Water Treatment Used? For corrosion controlCalcite filtration for pH adjustmentChemical injection for pH adjustmentOrthophosphate for sequestering
6 ANSI/NSF Standard 60 & 61All 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 EffectsNSF/ANSI Standard 44: Cation Exchange Water SoftenersNSF/ANSI Standard 53: Drinking Water Treatment Units - Health EffectsNSF/ANSI Standard 55: Ultraviolet Microbiological Water Treatment SystemsNSF/ANSI Standard 58: Reverse Osmosis Drinking Water Treatment SystemsVisit for more information
8 Considerations Before Installing Treatment Type and concentration(s) of contaminant(s)Treatment optionsNSF CertificationInitial cost of installing treatment equipment and ongoing costs of maintenance, chemicals, and additional water quality testingAvailable room to install treatment in existing pump houseSubmittal 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 systemStaff certified at the appropriate levelContracting 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 systemCorrect well violations and deficiencies firstEliminate cross connections within system piping firstUse alternate source of supplyGWR requires maintaining 4-log virus treatmentSource with significant deficiency or fecal contaminationExempt from GWR source water monitoring requirementExisting treatment systems need to demonstrate that treatment meets this levelA CT value of about 6 is necessary to achieve this levelRoutine 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
13 Chemical Injection Systems 4-log treatment systems must have must have redundancy or backup equipment immediately available4-log treatment systems must have redundancyor backup equipment immediately available.
14 Chlorination Systems Advantages Destroy bacteria, viruses, and other pathogenic microorganism, except Giardia and CryptosporidiumProvide a barrier of protection throughout the water system when an adequate chlorine residual is maintainedDisinfectant residual can be monitoredCan be used as an oxidant to suspend metals in solution for better filtration treatment performanceOxidizes hydrogen sulfide to reduce nuisance odor
15 Chlorination Systems Disadvantages More maintenance Chemical addition and disinfection by-productsNeed to maintain adequate contact time for effective disinfectionNeed to monitored on a daily basisRequires a higher certified operator skill levelMore space required for contact tank and treatment systemMineral oxidation may necessitate the need to install filtration treatment if raw water has mineral content.Iron and/or Manganese common in groundwater
16 Trivia QuestionsThe GWR requires what level of treatment at the entry point for effective virus inactivation / removal?4-logCan 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 metSource of supply is groundwaterBacteria (total coliform) is documented to be coming from the groundwater source (not in distribution system)UV unit meets ANSI/NSF 55 StandardsRaw water meets prerequisite water quality dataIron and Manganese, color, turbiditySuspended solid, hardness, hydrogen sulfide
18 Ultraviolet Disinfection AdvantagesNo chemicalsInstantaneous bacteria inactivationClosed systemNo disinfection by-productsLow maintenanceCan be installed in a relatively small space if pre-treatment is not necessaryRelatively low initial and maintenance costs compared to chlorination systems
19 Ultraviolet Disinfection DisadvantagesNo 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.
22 Trivia QuestionWhat are some of the raw water minerals to be concerned of when considering a UV treatment system?
23 Trivia QuestionWhat are some of the raw water minerals to be concerned of when considering a UV treatment system?ParameterMaximum LimitColor15Iron0.3 mg/LManganese0.05 mg/LHardness120 mg/LHydrogen SulfideNon-DetectableSuspended Solids10 mg/LTurbidity1.0 NTU
24 Granular Activated Carbon (GAC) Absorbs Organic Chemicalsgasoline, benzene, tolueneDDT, PCB, etc.Controls taste & odorChlorine smellSulfur odor (rotten egg smell)Typically 2 units are installed in series for organic removal
26 Aeration (Air Stripping) Multi-Staged Bubble System VOC Radon TTHM Hydrogen SulfideIron OxidationpH AdjustmentLowry Deep Bubble Air Stripper,
27 Iron/Manganese Removal Filtration is typically combined with pre-oxidationMedia: Manganese Greensand, Birm, MultimediaRegeneration / Oxidation: Potassium permanganateOxidation: Chlorine, Air injectionManganese is typically oxidized at a higher pH therefore pH adjustment may be requiredPhosphate – sequestering ironWater softenersBest 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
31 Trivia QuestionWhat is the purpose of air injection or aeration in the treatment process?OxidationVOC removalRadon removalpH adjustment
32 Water Softeners Removal of hardness Removal of iron and manganese Calcium and/or MagnesiumRemoval of iron and manganeseRegenerate with sodium chloride or potassium chlorideIf sodium levels are already elevated, potassium chloride may be preferableSodium 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 matterUse as pre-filter for other treatment processesSediment filter should be changed on a regular basisSpare filters should be kept in their original wrappingsAdd a tablespoon of bleach to filter housing after filter replacement
35 Trivia QuestionsWhat is one of the functions of a water softener in a treatment process?-- Hardness removal-- Iron and Manganese removalShould a cartridge filter be used for bacteria removal?No
36 Corrosion Control pH adjustment Calcite FilterChemical injectionIntroduction of corrosion control inhibitorsCalcite filters - protect scaling in pipesPhosphate chemical injection - applies a protective layer on the pipes to help prevent corrosion
37 Corrosion ControlEvaluate source Water Quality Parameters (WQP) resultsWQP – pH, alkalinity, calcium, conductivity, phosphate, temperatureBased on results, determine the most effective treatment systemAfter 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 contactorsRaise pH (typically not beyond 7.5)Add hardness (calcium carbonate) and alkalinity which can be beneficial for corrosion controlReplace 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 InjectionpH adjustment with potassium carbonate, sodium carbonate (soda ash), or hydroxide productsAllow a wider range of pH level to be achievedMore hazardous than a calcite filterPotential for chemical overfeed if chemical injection safety controls are not installedRecommend injection paced proportionate to flowSequestering with phosphateDaily 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 QuestionWhat is the monitoring requirement for the pH adjustment process?-- Calcite Filters - at least weekly pH readings-- Chemical injection – Daily pH readingsThe 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 softenerUsed to remove iron and manganeseCalcite raises pH and facilitates manganese removal with the water softenerCalcite adds hardness and water softener reduces hardnessWater softener followed by UV TreatmentWater softener reduces hardness, iron and manganeseBacteria passing through UV unit is inactivated and does not “hide” under larger mineralsMany other possible combinations
44 Neutralizer + Water softener + sediment filter + UV
45 Where does the backwash go? BACK WASH DISCHARGE MUST BE AIR-GAPPEDNot 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 wellMust be at least 10 ft from existing septic systemDEEP General Permit may be requiredBackwash discharge > 500 GPD
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 basinsProper mixing and safety instructions should be available for maintenance personnelAll chemical injection pumps must be controlled by an in-line flow sensor to prevent accidental overfeed in the case of a no-flow conditionChemical feed rates should be proportional to flowInjection pumps should be of the positive displacement typeChemical injection pumps are installed as near as practical to the injection pointA 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 controlsInstall two chemical injection pumpsSpare parts shall be available for chemical injection pumps to replace parts which are subject to wear and damageMake-up water line to the chemical solution tank must have proper backflow prevention device installedHoses 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 QuestionsIs 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 SystemsIf 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 operatorUV LightCalcite filter – media is replaced off site by licensed professionalCartridge filter (whole house filter, sediment filter)Exchange Softener – no backwash & media is regenerated off siteGranular Activated Carbon (taste & odor control)
56 Water Treatment Plant Classification Form Add up all the points and determine which level treatment plant appliesTREATMENT PLANT LEVELClass I 30 points or lessClass II pointsClass III pointsClass IV 76 points or greaterAvailable 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 rate8 gpm each (8,640 gpd each)Raw water qualityelevated iron, manganese, color & turbidity, 5.8 pHTreatment ProcessesChlorination, pH adjustment with KOH, greensand filters with potassium permanganate (KMnO4) for regeneration and intermittent backwash discharge to on-site dedicated disposal system