ARSENIC Info & Treatment
THERE ARE 2 TYPES OF ARSENIC – ARSENITE (As+3) and ARSENATE (As+5). * Arsenic found in a trivalent state: Arsenite (A+3) is predominately found in anaerobic ground water and is not considered to be oxidized.
Arsenic in drinking water can both stimulate the growth of cancerous tumors and cause them to spread faster. Studies indicate that Arsenic levels as low as 4 parts per billion (0.004 ppb) can stimulate blood vessel growth and levels as low as 10 parts per billion (0.010 ppb) can cause tumors to expand. Studies have also linked Arsenic ingestion and cancer – especially skin and bladder cancer. When water with Arsenic is ingested, the Arsenic reacts with oxygen to create “Free Radicals” – highly reactive molecules that stimulate the growth of blood vessels. More blood vessels result in an increased blood supply to any tumors present in and or on the body. This will cause them to grow faster and larger.
The EPA had set the current MCL (MAXIMUM Contaminate Level) of Arsenic in public drinking water at 50 ppb in 1975, based on the Public Health Service standard originally established in 1942. Before the end of President Clinton’s term in January 2001, the EPA issued a new standard of 10 ppb for Arsenic in drinking water only to reverse their decision until further studies related to COST associated with lowering the standard and the impact on public health can be conducted. This is despite the World Health Organization and European Union setting the WORLD standard of Arsenic in drinking water at 10 ppb and the studies that have shown 0 ppb to be the only level of Arsenic in water that is completely safe. Yes, the EPA recognizes the need to lower the standard from 50 ppb but is undecided where the level should be and has requested time to gather data in order to make an appropriate decision.
The EPA estimates as many as 13 million people in the USA routinely drink water with more than 10 ppb of Arsenic. If the MCL for Arsenic is lowered, costs are estimated at $5 to $20+ per household, per month, in larger municipalities while smaller community water systems will feel a greater financial impact.
POE TREATMENT FOR ARSENIC
- To treat dangerous levels of ARSENATE (As+5), the Nitrate, Sulfate, and Arsenate levels MUST be known. The water can be treated with TYPE II Strong Base Anion Resin such as A554. One cubic foot of this resin can remove up to 13,500 grains of anions when regenerated with 10 pounds of sodium chloride per cubic foot BUT because arsenic will start to bleed thru BEFORE other anions (lower capacity for Arsenic); it is recommended to limit the capacity (regenerate @ 5,000 total grains or 85,000 ppm). ALL Chlorine, Iron, and Hardness must be removed before the water is treated for Arsenic. Frequently testing the effluent water quality is recommended. *
- To treat dangerous levels of ARSENITE (As+3), it must be oxidized, in turn converting Arsenite (As+3) to Arsenate (As+5). This can be done by using Chlorine, Peroxide, Ozone, Manganese Greensand, Pyrolox or Potassium Permanganate. The benefit of using Manganese Greensand as the oxidizer is that it will also remove some of the Arsenic in the process.
This Manganese Greensand filter being regenerated with Potassium Permanganate is also known as an Iron Filter. Once the Arsenic is converted to Arsenate (As+5), it can be removed with the A554 Anion Resin. ALL Chlorine, Iron, and hardness must be removed before the water is treated for Arsenic. Frequently testing the effluent water quality is recommended.
Since there is no guarantee of absolute Arsenic removal using the above mentioned methods, these systems should always be followed up with a Reverse Osmosis or Distillation unit because of the level of danger Arsenic presents to the human body even in extremely small amounts.
SOLUTION: ADSORBSIA GTO
Adsorbsia GTO is a granular titanium oxide used for the removal of arsenic, lead and other heavy metals. A titanium-based media from Dow, it was developed to help municipalities comply with the 2006 EPA regulation of the MCL of arsenic. DOW states this new media has improved capabilities compared to all other commercially available media and has the following advantages:
- Highest capacity media over a wide range of water conditions
- Nanocrystalline structure results in fastest kinetics allowing for smaller diameter vessels and a smaller system footprint
- Removes both AS(3) and AS(5) across a wide pH range without use of pretreatment
- Stable performance during pH fluctuations
- Dry, white granule that is easily installed and maintained
- Also available in the powder form (ADSORBIA PTO media)
While pretreatment isn’t mandatory, Adsorbsia GTO would need pretreatment for an iron content of more than 0.1 pap. Also, it can remove both Arsenite (As+3) and Arsenate (As+5), but has 4 ½ times increased capacity removing only Arsenate (As+5). So, it would be advantageous to oxidize Arsenite (As+3+, turning it into Arsenate (As+5). This can be done by using an oxidizer such as chlorine and a retention tank for contact time before the Adsorbsia. The chlorine does not have to be removed from the water supply before the Adsorbsia like the above mentioned treatments require. It will pass thru the system without being sequestered, and unaffected. Regenerating and backwashing the Adsorbsia isn’t necessary but backwashing can be done to the media every few months to remove excess sediment that may have built up in the system. It has a flow rate of 10-12 gpm per cu ft. and the life expectancy will depend on the amount of arsenic in the water supply..