Gregory Korshin and Steve ReiberGregory Korshin and Steve Reiberkorshin@uw.edu, reiber@comcast.net

(partly based on materials prepared for the American Water Works Association, AWWA)

Drinking Water Treatment Drinking Water Treatment

in Small Utilities: a Review of Considerations in Small Utilities: a Review of Considerations

Typical for the United StatesTypical for the United States

Requirements for small water utilities in the United States

Water quality and treatment are under control of Water quality and treatment are under control of

the U.S. Environmental Protection Agencythe U.S. Environmental Protection Agency

The mission is to provide safe drinking water The mission is to provide safe drinking water

and protect public health.and protect public health.Small utilities must comply with the maximum contaminant Small utilities must comply with the maximum contaminant

level (MCL) established by the EPA for many contaminantslevel (MCL) established by the EPA for many contaminants

Regulations are same for large and small utilities, with some

exceptions

Water systems with < 15 connections (buildings) or serving < 25

people at least 60 days per year (campgrounds, schools,

summer houses) are not regulated under the National Primary

Drinking Water Regulations.

U.S EPA regions

10 EPA regions and 50 state

agencies

State regulations may be State regulations may be

much more stringent than much more stringent than

those the EPAthose the EPA

California is a typical

example

Very concerned with perchlorate,

Cr (VI), emerging contaminants

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Roles and Responsibilities under Safe Drinking Water Act (SDWA)

EPA sets health-based drinking water standards and oversees state programsEPA sets health-based drinking water

standards and oversees state programs

State environmental/public health agencies – Primary enforcement

responsibility/implement standards

State environmental/public health agencies – Primary enforcement

responsibility/implement standards

Public water systems are the regulated entity

Public water systems are the regulated entity

Consumers – Ultimate end-usersReceive benefits/pay costs

Consumers – Ultimate end-usersReceive benefits/pay costs

SDWA – Multiple Barrier Approach

5

Source ProtectionSource ProtectionTreatmentTreatment

DistributionDistribution Consumer Consumer ProtectionProtection

Turb. Turb. Disinf

ectionDistribution

Small system definitions

US EPA defines small water systems as US EPA defines small water systems as

those serving less than 3,300 population. those serving less than 3,300 population. In 2011, small water systems (>60,000 in total) had

significant problems:

They contributed to 95% of all community water systems

with monitoring and reporting violations

93% of systems with an maximum contaminant and

treatment technique violations.

Violations of Total Coliform Rule ranked the highest (48%)

Chemical Contaminant Group (25%),

Disinfectants and Disinfection Byproduct Rule (16%).

Issues typical for small utilities

For small water systems several issues are For small water systems several issues are

challenging: challenging:

Complying with monitoring and reporting

requirements;

Compliance with several EPA rules such as:

Total Coliform Rule,

Lead and Copper Rule

Radionuclide Rule

and many new regulations.

Special Challenge for Small Utilities: Arsenic Rule

Arsenic Rule Introduced in 20010.01 mg/L (or 10 ppb)5 years given to comply (Feb 2006)Includes non-community/non-transient water systemsCosts to utilities exceeding $ 5.4 billionSampling requirements- Annual for surface waters- Every three years for groundwater

Occurrence of arsenic in the US (red dots correspond to As> 1ppb)

Arsenic occurrence mapPopulation density in the United States (>

317 million total)

Outline of the “New” Arsenic Rule

The standard applies to 20,000 non-community systems that

serve at least 25 of the same people more than six months of

the year.

Schools, churches, nursing homes, and factories.

The EPA estimates that 5%, of these water systems, serving 2 million

people, have taken measures to meet the new arsenic standard.

This EPA rule applies equally to small and large This EPA rule applies equally to small and large

systems. Of the affected systems, 97% are small systems. Of the affected systems, 97% are small

systems that serve < 10,000 peoplesystems that serve < 10,000 people.

The rule does not apply to individual household well The rule does not apply to individual household well

systems, of which there are at least 50 million in the US.systems, of which there are at least 50 million in the US.

Exemption table

Major arsenic removal technologies

Coagulation/filtrationCoagulation/filtration

Excellent for point-of-entry treatment

Requires more sophisticated equipment and

training

Ion exchangeIon exchange

Can be highly efficient

Good for point-of-entry and point-of-use

applications

Problems in costs, high sulfate, brine handling

Adsorption Processes

AdsorptionAdsorptionRelatively popular As treatment method

A variety of excellent materials are available

Needs equipment, trained personnel, disposal of

spent media, may be costly

Sorption Processes: Adsorptive Media

Iron based mediaIron based media Granular Ferric Hydroxide, GFH (Siemens)E-33 (Severn Trent), Chemiron

Regenerable Iron coated Regenerable Iron coated resin resin (Solmetex)Iron Modified Activated Iron Modified Activated Alumina Alumina (Alcan)Other activated alumina Other activated alumina productsproductsOther adsorbents

Realities of implementation of the arsenic rule

Many of the small utilities with As issues did the Many of the small utilities with As issues did the

followingfollowing:

The high arsenic wells are frequently abandoned.

Or to blend with water from lower arsenic wells to bring

the blend below the 10 ppb MCL.

Adsorption of ferric hydroxide based media is Adsorption of ferric hydroxide based media is

relatively popularrelatively popular

But the adsorbent is pricey, and used on critical wells.

Arsenic Treatment Experiences (EPA)

EPA Treatment Demonstration EPA Treatment Demonstration

StudiesStudies

50 selected water systems in the US

31 Adsorption (62%)

2 Ion Exchange (4%)

15 Oxidation/Coagulation/Filtration (30%)

2 Reverse Osmosis (4%)16

Arsenic Treatment in the Washington State

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Realities of implementation of the arsenic rule

Ion-exchange is relatively rare Ion-exchange is relatively rare

Costs, sulfate and other limitations

Very few small systems resorted to ROVery few small systems resorted to RO

Too expensive for most systems.

If they got federal funding to do so, they may

buy an RO system.

Typically, federal funding is available for Indian

tribal reservations.

Occurrence of fluoride in the US (red dots correspond to F> 0.4 ppm)

Maximum contaminant Maximum contaminant

level for fluoride is 4 ppmlevel for fluoride is 4 ppm

Many utilities add fluoride Many utilities add fluoride

for dental healthfor dental health

Some people do not like this

Added fluoride

concentration close to 0.8

ppm

May be reduced to 0.6 ppm

Removal of fluoride

If high fluoride is an issue, the well is If high fluoride is an issue, the well is

usually abandoned. usually abandoned.

If this is not an option, then one of the one of the

few solutions is activated alumina. few solutions is activated alumina.

Maintaining an activated alumina system Maintaining an activated alumina system

is a serious chore for a small system.is a serious chore for a small system.

Point-of-use devices (e.g., “under the

sink” cartridges or small reverse osmosis

system) are popular with some people

Activated alumina columns (also good performance for arsenic)

Removal of salinity

Secondary MCL of 1000 mg/LSecondary MCL of 1000 mg/L

High salinity is a huge problem in High salinity is a huge problem in

many countries but genetally less so in many countries but genetally less so in

the USthe US

Very few utilities use reverse osmosis

Typically high salinity sources are Typically high salinity sources are

abandoned or blendedabandoned or blended

Point-of-use devices are also popular

Small systems and US realities

Most areas of North America have Most areas of North America have

reasonably abundant water sources. reasonably abundant water sources.

If a source becomes insufficient, an If a source becomes insufficient, an

alternative source is typically developed.alternative source is typically developed.

This will change due to global climate effects

and population growth.

Over 95% of small systems take water

directly from the ground, chlorinate and

distribute.

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Drinking Water – Missions and Visions

America’s America’s drinking water drinking water is safe, is safe, affordable, and affordable, and secure secure everywhere, everywhere, every day and every day and Americans Americans know it.know it.