The Driller
  • Sign In
  • Create Account
  • Sign Out
  • My Account
  • NEWS
  • CLASSIFIEDS
  • EQUIPMENT
  • SAFETY
  • VIDEOS
  • EDUCATION
  • SOURCEBOOK
  • EVENTS
  • SUBMIT
  • ABOUT
  • SIGN UP
cart
facebook twitter linkedin youtube
  • NEWS
  • Water
  • Geothermal
  • Construction
  • Environmental
  • Mining
  • All Industry News
  • EQUIPMENT
  • Rigs & Heavy Equipment
  • Consumables
  • Pumps
  • Featured Products
  • VIDEOS
  • Newscast
  • Drill Talks
  • Ask Brock
  • Emerging Drillers
  • EDUCATION
  • Drilling Business Insights
  • Reference Desk
  • Sponsored Insights
  • EVENTS
  • Conferences & Demo Days
  • Newscast LIVE
  • SUBMIT
  • Drillers @Work
  • ABOUT
  • Contact
  • Advertise
The Driller
search
cart
facebook twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
The Driller
  • NEWS
    • Water
    • Geothermal
    • Construction
    • Environmental
    • Mining
    • All Industry News
  • CLASSIFIEDS
  • EQUIPMENT
    • Rigs & Heavy Equipment
    • Consumables
    • Pumps
    • Featured Products
  • SAFETY
  • VIDEOS
    • Newscast
    • Drill Talks
    • Ask Brock
    • Emerging Drillers
  • EDUCATION
    • Drilling Business Insights
    • Reference Desk
    • Sponsored Insights
  • SOURCEBOOK
  • EVENTS
    • Conferences & Demo Days
    • Newscast LIVE
  • SUBMIT
    • Drillers @Work
  • ABOUT
    • Contact
    • Advertise
  • SIGN UP

Removing Arsenic from Drinking Water Supplies

May 1, 2005
Several processes have been developed for removal of arsenic from our drinking water.

Figure 1. Difference in molecular configuration of arsenate and arsenite.
Few U.S. Environmental Protection Agency (EPA) decisions have caused as much controversy as the adoption of the new standard for arsenic in drinking water. Some say the new standard is not low enough, given the health impacts of arsenic, while others say implementation of the new standard is just too costly. The arguments may rage on, but the fact remains: The new standard is about to come into effect, and everyone in the water industry should be aware of it and know how to deal with it.

Arsenic is a naturally occurring element present in ground waters in many parts of the world. Natural mineral deposits, agriculture and industrial pollution all are factors that contribute to the presence of arsenic in water. It has been well established that arsenic is toxic at high concentrations; however, recent research has shown that relatively low concentrations can cause adverse health effects, including cardiovascular problems, diabetes and various forms of cancer. For more than 50 years, the EPA-mandated maximum contaminant level (MCL) for arsenic in drinking water has been 50 parts per billion (ppb). However, as of January 2006, the acceptable level will be reduced to 10 ppb; it has been estimated more than 5 percent of all U.S. water supplies will be out of compliance.

Arsenic is stable in several oxidation states, but the two forms most commonly found in water are arsenate (As5+) and arsenite (As3+)(see Figure 1). Arsenic occurs in the arsenate form in most surface waters and oxidizing conditions, while in anaerobic ground waters and reducing conditions, arsenic exists mainly as arsenite. Arsenite can be oxidized to arsenate with oxidizing agents such as oxygen, chlorine or potassium permanganate. Since arsenate is more easily removed than arsenite, oxidation before treatment is the preferred protocol for waters containing high levels of arsenite.

Treatment Processes

Several processes have been developed for the removal of arsenic from drinking water. A brief overview of the most common technologies is given below:

Industrial pollution is a factor contributing to the presence of arsenic in water. Photo courtesy of the U.S. EPA.

Coagulation/Filtration

A chemical reagent (such as lime, ferric hydroxide or alum) that forms insoluble arsenic compounds is added to the contaminated water; these arsenic compounds then can be removed by sand filtration. This method of arsenic removal originally was used for treating mining effluents where the arsenic is present at high concentrations, however it has been shown effective with drinking water in certain instances as well.

Three problems with using such treatment of drinking water are:

(1) the treatment chemical often affects the pH of the treated water (this is especially true for the most effective chemical - ferric chloride);

(2) the dosage of coagulant chemical has to be fairly high (3 mg/l to 5 mg/l ferric chloride for 50 ppb arsenic); and

(3) a relatively large volume of waste sludge is produced.

Ion Exchange on Polymeric Resins

Ion exchange resins work simply by exchanging one ion from the resin surface for a like-charged ion in the water passing over it. This technique can work well in some instances, but usually is poor in its selectivity. For anion exchange resins, sulfate, selenium and nitrate all are preferred over arsenic, and their presence therefore will reduce the resin's arsenic adsorption capacity. Additionally, the effectiveness of ion exchange often is severely affected by the presence of high salt concentrations. Ground and surface waters frequently have high levels of inorganics, which makes this method unsuitable as an effective method for treating such waters. Disposal of spent brine regenerant solution also may be problematic.

Reverse Osmosis/ Nanofiltration

This method is extremely effective in removing (“rejecting”) salts and ions (including arsenate), but it is not selective.

The rejection of scale-causing ions such as calcium leads to the precipitation of these materials on reverse osmosis (RO) and nanofiltration (NF) membranes. This typically results in fouling of the membrane surface and must be avoided by adding anti-scaling chemicals and/or acid washing. Additionally, RO and NF processes often have a poor recovery rate (i.e., often 50% or more of the incoming water is wasted). Another disadvantage is that large amounts of concentrate waters are generated and must be disposed.

Adsorption

Adsorption of arsenic normally is achieved by filtering arsenic-contaminated water through a column of granular arsenic-adsorbing media.

For decades, activated alumina (Al2O3) was the media of choice for adsorption of arsenic. However, this media's performance is very pH-dependent (pH of 5.5 is required for best performance) and is affected by high concentrations of fluoride, sulfates and chlorides. The possibility of aluminum leaching into water also may be a concern.

Granular ferric hydroxide and granular ferric oxide are two types of adsorptive media developed by German companies to take advantage of arsenic-ferric ionic attraction. Advantages of these media include a relatively high operating pH range (up to 8) and good adsorption capacity. However, they cannot be regenerated (single-use) and are negatively affected by the presence high concentrations of iron and silica. There also is arsenic-removal media available on the market that is unaffected by fluorides, chlorides, sulfates and iron, and can be regenerated for re-use after arsenic saturation.

In summary, there are several options available for arsenic treatment, and no single technology is best for every application. Water chemistry, speciation of arsenic (arsenate or arsenite), daily water usage, and maximum flow rate all must be considered before selecting a technology. Equally important are the qualifications of the technology provider: Is the technology patented? Is it NSF-certified? Does it have third-party (e.g., ETV) performance verification? What sort of track record does the company have and how long has it been in business? With a little background knowledge and by asking the right questions, you can improve your chances of getting the technology that's right for you and your customers.
ND

Share This Story

Looking for a reprint of this article?
From high-res PDFs to custom plaques, order your copy today!

Recommended Content

JOIN TODAY
to unlock your recommendations.

Already have an account? Sign In

  • geotechnical drilling rig

    6 Onsite Phrases Environmental Drillers Hate

    Here are six phrases that highlight common frustrations...
    Markets
    By: Jeff Garby
  • Wayne Nash

    Pipe Stuck? Common Causes and Solutions for Drillers

    If you have drilled for any length of time, sooner or...
    World According to Wayne
    By: Wayne Nash
  • submersible pumps, water well pumps

    Selecting and Sizing Submersible Pump Cable

    This article helps pump installers and servicers decide...
    Markets
    By: Bob Pelikan
You must login or register in order to post a comment.

Report Abusive Comment

Subscribe For Free!
  • eNewsletters
  • Online Registration
  • Subscription Customer Service
  • Manage My Preferences

The Driller Newscast: Coiled Tubing Drilling and the Future of Geothermal

The Driller Newscast: Coiled Tubing Drilling and the Future of Geothermal

The Driller Newscast: New York Geo Talks 2025 Conference with Hands-on Driller Education

The Driller Newscast: New York Geo Talks 2025 Conference with Hands-on Driller Education

The Driller Newscast: 21st Century Drillers | Part 1 DEMAND

The Driller Newscast: 21st Century Drillers | Part 1 DEMAND

The Driller Newscast, Episode 147: Global Geothermal Collaboration at NY-GEO 2025

The Driller Newscast, Episode 147: Global Geothermal Collaboration at NY-GEO 2025

More Videos

Sponsored Content

Sponsored Content is a special paid section where industry companies provide high quality, objective, non-commercial content around topics of interest to the The Driller audience. All Sponsored Content is supplied by the advertising company and any opinions expressed in this article are those of the author and not necessarily reflect the views of The Driller or its parent company, BNP Media. Interested in participating in our Sponsored Content section? Contact your local rep!

close
  • demo of a DM450 drilling rig during a customer factory visit
    Sponsored byGeoprobe

    Built for You: Smarter Drill Rigs, Stronger Support, Bigger Opportunities

Popular Stories

MainPhotoTwoBrothers.jpg

Two Brothers' Journey Through the Drilling Industry

AI and Drought Concerns

AI’s Growing Thirst for Water and Power

demo of a DM450 drilling rig during a customer factory visit

Built for You: Smarter Drill Rigs, Stronger Support, Bigger Opportunities

The Driller Classifieds

COMPRESSORS

EAST WEST MACHINERY & DRILLING IS BUYING AND SELLING AIR COMPRESSORS, AIR BOOSTERS, AIR ENDS & PARTS
Company: East West Machinery

DRILL RIGS

LOOKING FOR LATE MODEL TOPHEADS & DRILLTECH D25'S
Company: Spikes’s Rig Sales

DRILL RIG PARTS

MEETING DRILLERS NEEDS AROUND THE WORLD
Company: East West Machinery

ELEVATORS

SEMCO INC. PIPE ELEVATORS
Company: Semco Inc.

GROUTERS

GROUTING EQUIPMENT - GROUT PUMPS & GROUT HOSE REELS
Company: Geo-Loop Inc.

PUMP HOISTS

SEMCO INC. - BASIC PUMP HOISTS
Company: Semco Inc.

WELL PACKERS

LANSAS PRODUCTS - INFLATABLE WELL PACKERS
Company: Vanderlans Lansas Products

WELL SCREENS

WELL SCREENS & SLOTTED PIPE
Company: Alloy Screen Works

Products

Water Quality Engineering: Physical / Chemical Treatment Processes

Water Quality Engineering: Physical / Chemical Treatment Processes

By carefully explaining both the underlying theory and the underlying mathematics, this text enables readers to fully grasp the fundamentals of physical and chemical treatment processes for water and wastewater.

See More Products

Subscribe to The Driller Newscast

Related Articles

  • Gas Drilling's Impact on Drinking Water Supplies

    See More
  • Contaminants from Drinking Water Supply Pipes

    See More
  • Desalination Can Boost Water Supplies, But ...

    See More
×

Dig deeper into the drilling and water supply industry!

Build your knowledge with The Driller, covering the people, equipment and technologies across drilling markets.

SIGN UP NOW
  • RESOURCES
    • Advertise
    • Contact Us
    • Directories
    • Store
    • Want More
    • Classifieds
  • SIGN UP TODAY
    • Create Account
    • eNewsletters
    • Customer Service
    • Manage Preferences
  • SERVICES
    • Marketing Services
    • Reprints
    • Market Research
    • List Rental
    • Survey/Respondent Access
  • STAY CONNECTED
    • LinkedIn
    • Facebook
    • YouTube
    • X (Twitter)
  • PRIVACY
    • PRIVACY POLICY
    • TERMS & CONDITIONS
    • DO NOT SELL MY PERSONAL INFORMATION
    • PRIVACY REQUEST
    • ACCESSIBILITY

Copyright ©2025. All Rights Reserved BNP Media.

Design, CMS, Hosting & Web Development :: ePublishing

The Driller
search
cart
facebook twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
The Driller
  • NEWS
    • Water
    • Geothermal
    • Construction
    • Environmental
    • Mining
    • All Industry News
  • CLASSIFIEDS
  • EQUIPMENT
    • Rigs & Heavy Equipment
    • Consumables
    • Pumps
    • Featured Products
  • SAFETY
  • VIDEOS
    • Newscast
    • Drill Talks
    • Ask Brock
    • Emerging Drillers
  • EDUCATION
    • Drilling Business Insights
    • Reference Desk
    • Sponsored Insights
  • SOURCEBOOK
  • EVENTS
    • Conferences & Demo Days
    • Newscast LIVE
  • SUBMIT
    • Drillers @Work
  • ABOUT
    • Contact
    • Advertise
  • SIGN UP