Arsenic, a naturally occurring element, is found in varying concentrations in the Earth’s crust worldwide. While organic arsenic compounds, like those in seafood, are generally less harmful, inorganic arsenic in water is highly toxic. Arsenic cannot be destroyed—it only changes form, often binding to tiny particles that can become airborne and travel long distances before settling into water sources like lakes, rivers, or groundwater.
The Hidden Danger of Arsenic
The primary source of unintentional arsenic exposure is drinking contaminated groundwater. In the U.S., about 80% of water supplies contain less than 2 ppb (parts per billion) of arsenic, but 2% exceed 20 ppb, posing significant health risks. Chronic exposure to even low levels (below 0.05 mg/L) is linked to serious health issues, including:
- Cancers of the skin, kidney, lung, and bladder
- Skin, neurological, and cardiovascular diseases
- Diabetes, oxidative stress, DNA damage, and immune system issues
Acute poisoning causes severe symptoms like gastroenteritis, vomiting, diarrhea, convulsions, and, in extreme cases, death from circulatory failure. Inorganic arsenic is metabolized and partially excreted, but some remains in the body indefinitely, disrupting cellular metabolism.
Arsenic in Water: Key Facts
Arsenic exists in water as various species, with the most common being:
- Arsenite (AsIII): Trivalent, highly toxic, and easily absorbed by the body.
- Arsenate (AsV): Pentavalent, also toxic but less readily absorbed. Other forms include monomethylarsonous acid (MMAIII), monomethylarsonic acid (MMAV), dimethylarsinic acid (DMAIII), dimethylarsinic acid (DMAV), and trimethylarsine oxide (TMAO).
Challenges in Arsenic Removal
Removing arsenic from water is complex due to its high molecular weight and competition from other ions, such as phosphates, which vie for exchange sites on filtration media. Key factors affecting removal include:
- pH: Neutral pH (~7) is optimal; lower pH can render arsenic insoluble, reducing removal efficiency.
- Phosphate and Silica: These compete with arsenic for binding sites, lowering capacity.
- Other Oxyanions: Vanadium, selenite, molybdate, and chromate also reduce removal efficiency.
- Flow Rate and Contact Time: Higher flow rates or shorter contact times lead to earlier breakthrough and reduced capacity.
Tradewinds Water offers advanced arsenic removal systems designed for reliability and efficiency, available in single-tank or lead/lag configurations. Key features include:
- NSF/ANSI Standard 61 Certified Media: Safe and effective.
- Proven Iron Chemistry: Enhances arsenic adsorption.
- No Backwash or Fines: Simplifies maintenance.
- Central Regeneration: Extends media life.
- Low Pressure Drop: Ensures optimal flow dynamics.
- Rapid Adsorption Kinetics: Fast, effective contaminant removal.
- TCLP-Compliant Media: Safe disposal of spent media.
A comprehensive water test and engineering evaluation are critical before installing an arsenic removal system. Essential data includes:
- Arsenic III and V levels (ppb)
- Vanadium, phosphate, and silica concentrations
- pH and other oxyanions (e.g., molybdate, selenite)
- Peak flow rate and daily water usage
- Target maximum arsenic level in treated water
Conclusion
Arsenic in water is a serious health threat, but with proper testing and advanced filtration systems like those from Tradewinds Water, it can be effectively managed. Protect your water supply by understanding local arsenic levels and implementing a tailored, high-performance treatment solution.
For more information, contact Tradewinds Water for details on advanced water treatment technologies.