Q: Why is arsenic found in groundwater and why is it difficult to remove?
A: While arsenic is naturally found in rocks and soil and is released into water supplies through erosion, some industrial practices also have the potential to release arsenic into the environment. Arsenic can be discharged into groundwater as a byproduct of the industrial treatment process during the production of paints and dyes, metals, soaps, drugs and wood preservatives. Arsenic can be difficult to remove because it is soluble and dissolves in water.
Q: What health risks are associated with arsenic consumption?
A: Inorganic arsenic compounds, such as those found in water, are highly toxic. According to the World Health Organization (WHO), acute arsenic poisoning can result in vomiting, abdominal pain and diarrhea. These initial symptoms may be followed numbness and tingling of the extremities, muscle cramping and even death. Arsenic and arsenic compounds are classified as carcinogenic to humans by the International Agency for Research on Cancer.
Long-term exposure to inorganic arsenic may cause developmental effects, neurotoxicity, diabetes, pulmonary disease and cardiovascular disease. According to WHO, “arsenic is also associated with adverse pregnancy outcomes and infant mortality, with impacts on child health, and there is some evidence of negative impacts on cognitive development.”
Q: What makes adsorption an effective option for removing arsenic?
A: There are various options for removing arsenic, including ion exchange, activated alumina, reverse osmosis, coagulation/filtration and adsorption.
While coagulation/filtration can prove effective when treating water with high levels of multiple contaminants, it has higher initial capital costs and is more labor intensive. It is more complex than adsorption, which can be a key concern for utilities without centralized treatment plants. Adsorption is a simple, passive process with a relatively low cost. One advantage of iron adsorption is the predictability of the breakthrough. Comparatively infrequent monitoring of performance can give optimum performance for removal of both arsenate and arsenite.
Top: Adsorption media is an effect arsenic removal technique. Bottom: Arsenic is naturally found in rocks and soil, but also can be released into the groundwater via industrial activities.
