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WELCOME!

This training is presented by RCAC with funding provided by the California State

Water Resources Control Board Division of Drinking Water (DDW)

The Rural Community Assistance Partnership

RCAC

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RCAC Programs

Affordable housingCommunity facilitiesWater and wastewater infrastructure

financing (Loan Fund)Classroom and online trainingOn-site technical assistance Median Household Income (MHI) surveys

Control Tabs

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Audio Controls

Attendee List

Today’s Materials

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Marking Tool

Hide/Restore Control Panel

Questions?

Text your questions and comments anytime during the session

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Performance Assessment Rating Tool (PART)

4 to 6 weeks from todayEmail w/ today’s workshop in subject line3 questions – 3 minutes maximumHow did you use the information that was

presented today?Funders are looking for positive changesHelp us continue these free workshops!

Your Moderator Today…

Michael BoydRural Development

Specialist:Environmental

Gering, NE

mboyd@rcac.org

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Today’s Trainer

Angela HengelRural Development

Specialist II –Environmental/Tribal

San Marcos, CA

ahengel@rcac.org

Questions?

Text your questions and comments anytime during the session

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Water Treatment Techniques

Today’s Agenda

Water sources

Regulatory requirements

Conventional water treatment

Additional treatment technologies

Resources

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Poll #1

Hydrologic Cycle

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Where is most of the water?Percentage

Oceans 97.2

Ice Caps & Glaciers2.14

Groundwater 0.61

Surface Water 0.009

Soil Moisture 0.005

Atmosphere 0.001

Aquifers As water percolates through soil it

ultimately reaches impervious rock or strata.

Eventually, all the voids in the soil become permeated with water. This saturated area is known as the saturation zone.

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Water Sources - Groundwater

Saturation Zone: All the voids in the soil are permeated with water

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Water Table: The upper surface of the zone of saturation is known as the water table

Types of Aquifers

Unconfined aquifer – the aquifer is has an impervious layer beneath it, but is unconfined. Known as water table aquifer.

Confined aquifer – the aquifer is between two impervious layers (clay or rock)

If the confined aquifer is under pressure it is known as an “Artesian Aquifer”

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Groundwater ProsGroundwater that is not under the influence of surface water is generally:

Lower in organics

Less prone to contamination

Lower in turbidity

Requires less treatment than surface water

Not subjected to surface water regulations

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Groundwater ConsGroundwater is typically:

Higher in minerals

Harder water due to minerals (Ca & Mg)

Difficult to mitigate if contaminated

May be prone to: iron and manganese, radionuclides, arsenic, hydrogen sulfide (source of “rotten egg” odors), nitrates

Sources of Contamination

Storage Tanks

Septic systems

Uncontrolled Hazardous Material disposal

Landfills

Chemical and Road Salts

Pesticide and Fertilizer use

Cows

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Groundwater Contaminant Sources

Questions?

Text your questions and comments anytime during the session

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Water Sources – Surface Water

Water Quality – Surface Water

Falls under the SWTR

Higher in organics

Higher in turbidity

Softer water

Microbial contamination

Easier to pollute

Easier to contaminate

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The Multiple Barrier Approach

The Multiple Barrier Approach

Risk Prevention - assessing and protecting drinking water sources

Risk Management – using effective treatment, properly designed and constructed facilities, certified operators

Monitoring and Compliance – detecting and fixing problems in the distribution system

Individual Action - Making information available to the public on the quality of their drinking water

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Surface Water Treatment Rule

California Code of Regulations, Chapter 17, Title 22, “Surface Water Treatment”

(1) A total of 99.9 percent reduction of Giardia lamblia cysts through filtration and disinfection;

(2) A total of 99.99 percent reduction of viruses through filtration and disinfection; and

(3) A total of 99 percent removal of Cryptosporidium through filtration.

Surface Water Treatment Rule

REDUCTION is achieved by Multi-Barrier Treatment: a series of water treatment processes that provide for both removal and inactivation of waterborne pathogens

Removal = Filtration

Inactivation = Disinfection

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Surface Water Treatment Rule

Removal

A set amount of “credit” (towards reduction) will be obtained depending on which kind of filtration a plant utilizes. “Approved” Filtration:

Filtration Giardia Credit Virus Credit

Conventional 2.5 2

Direct 2 1

Diatomaceous Earth

2 1

Slow Sand 2 1

Alternative Filtration Technology

§64653. Filtration.

(e) An alternative to the filtration technologies specified in subsection (a) may be used provided that the supplier demonstrates to the State Board that the alternative technology:

(1)Provides a minimum of 99 percent Giardia lamblia cyst removal, 90 percent virus removal for the suppliers serving more than 500 persons, and 99 percent Cryptosporidium removal; and

(2) Meets the turbidity performance standards established by the State Board

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Surface Water Treatment Rule

Inactivation

All approved surface water utilized by a supplier shall be provided with continuous disinfection treatment sufficient to insure that the total treatment process provides inactivation of Giardia lamblia cysts and viruses, in conjunction with the removals obtained through filtration

CT = Residual disinfectant concentration x contact time

Quick Quiz 1

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Conventional Water Treatment

Conventional water treatment consists of four processes:

1. Coagulation

2. Flocculation

3. Sedimentation

4. Filtration

Conventional Vs. Direct

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Coagulation – Flash Mix

Coagulation – the water treatment process that causes very small suspended particles (turbidity) to attract one another and form larger particles called floc

Coagulation process – breaks down the negative charge and allows particles to come together, a.k.a. destabilization

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Most colloidal particles in water are surrounded by negative electrical charges

Negatively charged particles repel each other like negative poles of magnets

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Coagulants neutralize the negatively charged particles

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Coagulation - Dosage

Dosage is determined by the jar test

Multiple liter jars filled with raw water

Placed on mixer to imitate flash mix

Coagulant added in milligrams (mg)

Water and coagulants mixed

Mixer turned off, observe settleability

Best dosage in mg/L, apply to system

Process Control – Jar Testing

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Quick Quiz 2

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Flocculation

Flocculation – the process of gently mixing in order to enhance collision of floc particles while not breaking them apart, a.k.a. agglomeration. The action takes place in flocculation basins

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Horizontal Flocculator

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Quick Quiz 3

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Sedimentation

Sedimentation – solids removal by gravity, a.k.a. clarification.

Treatment plants that include coagulation, flocculation, sedimentation and filtration are known as Conventional Treatment Plants.

Treatment plants without sedimentation are known as direct filtration plants.

Sedimentation

Sedimentation process – sedimentation allows for a decreased velocity of flow which lessens the ability of the water to hold particles in suspension. It allows the force of gravity to overcome the force of velocity. Sedimentation takes place in a sedimentation basin

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Sedimentation

Conventional Rectangular basins –designed to provide uniform horizontal low velocity flow, a.k.a. rectilinear flow or plug flow.

Circular basins - Center feed basins, peripheral feed basins, and spiral flow

BaffleEffluent LaunderInfluent

Zone

Settling Zone

Effluent Zone

Sludge Zone

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Upflow Clarifier

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Questions?

Text your questions and comments anytime during the session

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Filtration

Filtration – the removal of suspended material by passing the material through a porous medium. Filtration removes turbidity. Turbidity can shield pathogens from disinfection.

Filtration

Filtration process– the most importation action that occurs within a filter is adsorption.

The filter media has a large surface area. As water passes through the filter bed, the suspended particles contact and adsorb (stick) onto the surface of the individual media grains or onto previously deposited material.

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Filtration Basics

Slow Sand Filtration

Slow Sand – a layer of fine sand about 3.5 feet atop about 1 foot gravel

The primary filtering mechanism is the Schmutzdecke (biological layer)

They are not used with coagulants

Flow rate is only 0.05 gpm/ft2

These filters are not backwashed, instead the top 1 inch is scraped off

It may take days for the schmutzdecke to re-form

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Slow Sand Filter

Slow Sand Filter

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Rapid Sand Filter

Capable of 2 gpm/ft2 filter rate of flow.

Utilizes coarser sand than slow sand filters

Is used with coagulants

Use of coagulants allows for a much smaller footprint

Rapid Sand Filters

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Dual Media, High Rate Filter – Utilizes 2 types of filter media, typically:

Anthracite – lighter, stays on top

Sand – more dense, stays below anthracite

Gravel – supports the filter media

Typical High Rate, Dual Media Filter

Typical High Rate, Multi-Media Filter

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Filtration

Sand, anthracite, granular activated carbon, and garnet are all examples of filter media.

SAND

GARNETANTHRACITE

Quick Quiz 4

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Diatomaceous Earth Filtration

Diatomaceous Earth is the fossilized skeletal remains of single celled aquatic plants called diatoms

As they form, diatoms produce a porous exoskeleton

When the diatom dies, the exoskeleton remains behind

There are diatomaceous earth deposits in several sites in the western U.S.

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Diatomaceous Earth Filtration

Operation of a DE filter:

1. Precoat of DE is fed to filter element (septum)

2. During filtration, a body feed of DE is fed to filter

3. Backwash takes place when a predetermined pressure loss across the filter is reached

Alternative Filtration Technology

§64653. Filtration.

(e) An alternative to the filtration technologies specified in subsection (a) may be used provided that the supplier demonstrates to the State Board that the alternative technology:

(1)Provides a minimum of 99 percent Giardia lamblia cyst removal, 90 percent virus removal for the suppliers serving more than 500 persons, and 99 percent Cryptosporidium removal; and

(2) Meets the turbidity performance standards established by the State Board

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Description of membrane process

Water forced through a porous membrane under pressure while larger molecules are held back

Microfiltration

Ultrafiltration

Nanofiltration

Reverse Osmosis

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Hollow fiber membranes

RO Filter Pore Water Molecule Dissolved Metals

Viruses

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Protozoa

Bacteria

Questions?

Text your questions and comments anytime during the session

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Disinfection Introduction

Disinfection, also known as inactivation, is a water treatment process designed to destroy or inactivate pathogenic organisms

Remember, multi barrier treatment calls for removal & inactivation

DisinfectionFiltration

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Pathogenic Organisms

Pathogenic organisms are disease causing organisms and include:

Bacteria

Viruses

Protozoa

Pathogenic Organisms

What is the primary health risk associated with pathogenic drinking water organisms?

Gastrointestinal illness

Vomiting

Diarrhea

Maybe no symptoms

Most at risk: infants, elderly, people with compromised immune systems

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Primary and Secondary Disinfection

Primary disinfection achieves the desired level of inactivation of disease causing organisms

Secondary disinfection provides a residual in the finished water

Disinfection - Physical

Disinfection can be achieved using physical and chemical methods:

Examples of Physical methods include:

Heat

Ultra Violet Radiation (UV)

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U-V Tube

U-V Unit

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Quick Quiz 5

Disinfection - Chemical

Chemical Disinfectants include:

Chlorine

Chloramine

Ozone

Chlorine Dioxide

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Choice of Disinfectant

All disinfectants have advantages and limitations

There are numerous factors involved in deciding on a disinfectant

Disinfectants may have other purposes

Chlorine is the most common disinfectant used in the US

Chlorine for Disinfection:

Readily Available

Inactivates pathogenic organisms

Relatively Inexpensive

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Chlorine for Disinfection:

Leaves a lasting residual

Long history of use in the United States

Chlorine for Disinfection:

Chlorine can be used as both a primary and a secondary disinfectant

Primary disinfection achieves the desired level of inactivation of disease causing organisms

Secondary disinfection provides a residual in the finished water

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Dosage and Residual

The amount of chlorine applied to the water is called the dosage

typically expressed in mg/L (or ppm)

Chlorine residual is the measurement of chlorine concentration in the water after treatment

expressed in mg/L (or ppm)

Chlorine Dosage

Demand – the amount of chlorine required to reach breakpoint

Residual – the desired chlorine concentration in the finished water

Demand + Residual = Dosage

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Chlorine Dosage

Demand 2 mg/L

+ Desired residual 1 mg/L

Dosage 3 mg/L

Types of Chlorine Residual

Two types of chlorine residual

Free chlorine residual

Combined chlorine residual

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Types of Chlorine ResidualCombined Chlorine

When free chlorine reacts with nitrogen compounds, chloramines are formed

Ammonia is added to water containing free chlorine to form chloramines

This process is called chloramination

The resulting residuals are known as combined residuals

Types of Chlorine ResidualCombined Chlorine

The three chloramines are:

Trichloramine,

Dichloramine

Monochloramine

Of the three, monochloramines are preferred

Formation of chloramines is controlled by adjusting the chlorine and ammonia ratios

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Types of Chlorine ResidualCombined Chlorine

The decision to use chloramines depends on each water system’s needs

In general, chloramines:

Are weaker disinfectants than free chlorine

May require higher concentration and longer contact times

Types of Chlorine ResidualCombined Chlorine

In general, chloramines:

Provide a longer lasting residual than free chlorine

Create fewer harmful disinfection by-products than free chlorine

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Types of Chlorine ResidualTotal Chlorine

Together, free chlorine residual plus combined chlorine residual is known as the total chlorine residual

Free Chlorine + Combined Chlorine = Total Chlorine

Chlorine Dioxide CIO2

Must be generated on site (unstable) combining sodium chlorite (liquid or powder) and chlorine solutions at low pH

Greenish yellow gas, odorous

Powerful oxidant

Developed to aid in taste and odor issues

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Chlorine Dioxide CIO2 - Pros

Lack of TTHM formation

Effective killing bacteria and viruses

Does not combine with ammonia

Oxidizes iron and manganese

Removes color

Taste and odor control

Somewhat effective against cryptosporidium

Does not create carcinogens

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Chlorine Dioxide CIO2 - Cons

Can create chlorates and chlorites

Gives water distinct taste, undesirable to some

Higher level operator needed

Cat urine odor

Ozone (O3)

Bluish, toxic gas with pungent odor

Ozone generated by passing a high voltage between two electrodes allowing the O2 to split, reattach and become O3

Oxygen must be dry, and particle free

Very effective disinfectant, powerful oxidizer

Must be generated on site, not transportable

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Ozone (O3) - Pros

Very powerful disinfectant, not proven to be carcinogenic (if no bromide exists)

Also effective for color, taste and odor

Less likely to create disinfection by products, assuming no bromide (creates Bromate)

Improves coagulation process, which lowers chemical cost, reduces sludge disposal and lengthens filter runs

Ozone (O3) - Cons

Equipment is expensive

High electrical costs

Residual does not last

Need to add disinfectant with residual afterwards

Large foot print

Higher level operator needed

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Questions?

Text your questions and comments anytime during the session

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Water Quality - Nitrate & Nitrite

Primary Drinking Water Standard

Health Concern

Blue Baby Syndrome- Methemoglobinemia

Nitrates (NO3)

Sources

Fertilizers

Human and Animal Waste

Atmospheric Deposition

Treatment – The BAT is ion exchange, coupled with reverse osmosis

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Water Quality - Hardness

Hardness reported as mg/L as CaCO3 (calcium carbonate)

Hardness Classification:

Soft: 0 to 17 mg CaCO3/L

Slightly Hard: 17 to 60 mg/L;

Moderately Hard 60 to 120 mg/L

Hard 120 to 180 mg/L

Very Hard > 180 mg/L

Hard Water Treatment

Ion Exchange

Media (zeolites) exchange sodium ions for hardness ions

Chemical Precipitation

pH adjustment causes soluble hardness ions to precipitate

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Operation Of Ion Exchange Unit

Softening – Hard water is fed through the unit until unit can no longer soften water

Backwash – Treated water flowed in opposite direction to remove foreign material, loosen resins and mix resins

Regeneration cycle – 10% salt brine passed through filter resins for 20-30 minutes, sodium ions exchange for calcium and magnesium ions

Rinse cycle – Rinses out unused salt

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Ion Exchange

Pros:

Lower initial costs

Smaller space requirements

Automatic controls, minimal staff

The only chemical used in this process is salt (Na), safe and easy to handle

Ion Exchange

Cons:

Increased sodium content in finished water

Disposal of regeneration waste

More expensive to operate than chemical precipitation

Not practical for surface water, due to turbidity and algae fowling media

Removes all hardness, creating corrosive water

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Ion Exchange additional uses

Used to remove inorganic constituents that cannot be removed by filtration/sedimentation

It can also be used to remove arsenic, chromium, excess fluoride, nitrates, radium, and uranium

Water Softening – Chemical Precipitation

Addition of chemicals that raise pH well above neutral

Calcium and magnesium become less soluble as pH rises

Hardness causing ions converted from soluble to insoluble

Insoluble precipitates allowed to settle out and/or to be filtered out

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Water Softening – Chemical Precipitation

Pros –

Also can remove iron and manganese

Reduction of total solids

Inactivate bacteria/viruses due to high pH

Removal of excess fluoride

Water Softening – Chemical Precipitation

Cons–

Finished water may have very high pH –11 or more, and requires pH adjustment

May produce large amounts of lime sludge

Extra facilities required

Softening chemicals are very caustic (strong base)

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Taste And Odor Control

Treatment:

Coagulation, flocculation, sedimentation

Aeration, with volatile gasses and organic compounds only

Air stripping (air diffusers)

Chlorine, chlorine dioxide, potassium permanganate, ozone

PAC (powdered activated carbon) or GAC (granular activated carbon)

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Questions?

Text your questions and comments anytime during the session

Resources

California Drinking Water Regulations http://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/documents/lawbook/dwregulations-2014-07-01.pdf

Water Board web site

http://www.waterboards.ca.gov/drinking_water/programs/index.shtml

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RCAC staff…

mboyd@rcac.org

ahengel@rcac.org

Thank you for attending!