Arsenic Poisoning in Water...

Arsenic is a naturally occurring mineral that can be found in soil, bedrock, and, ground water. It is a highly poisonous metallic element that has three allotropic forms, which are yellow, black and gray, it also occurs in the three states of matter which are liquid, solid and gas. Sometimes found in its pure form as a metal, it is usually a part of chemical compounds such as inorganic and organic. 

Inorganic compounds mean it combines with oxygen, iron, chlorine or sulfur.  Organic compounds mean it combines with carbon and other atoms.  It is often found in drinking water at levels from several hundred to several thousand parts per billion (ppb) and can be in high concentrations in industrial areas and near agricultural activity and cannot be detected by smell or taste.  

The naturally occurring inorganic arsenic is formed from the weathering and decomposition of soil and minerals as well as from volcanic activity.   Inorganic arsenic can also be produced through anthropogenic means such as: ore smelting, burning of coal, pesticide use and combustion of fossil fuel.  

Research of arsenic in water dates back to 1975 and has been noted as an issue for quite some time.  Arsenic contamination of ground water can be found in many countries throughout the world as well as the USA and is known to cause health issues in individuals that ingest it.  

As stated, the USA has had its issues with arsenic in its drinking water in many of its states. “Water in some areas of the United States, especially in the West, contain high levels range from 50 to 100 ppb.”   Based on research by the United States Geological Survey (USGS) such states as California, Oregon, Nevada, Texas, Montana and Minnesota has reported  high levels of arsenic in their drinking water.  

The Figure  below shows the levels of contamination by state as reported by USGS.

Besides the United States of America, it has been found that arsenic poisoning from groundwater has also been reported in recent years in countries such as China, Argentina, Chile and Bangladesh.  In Bangladesh alone, over a million Bangladeshi villagers have been poisoned by groundwater that contains naturally occurring arsenic. 

In an attempt to provide clean drinking water to this poor country, tube wells (steel pipes fitted with simple hand pumps) were sunk to aid the villagers in acquiring water naturally by the United Nations Children’s Fund (UNICEF) as well as various world organizations with no knowledge of the fact that the groundwater would contain arsenic.

Today over a billion Bangladeshis are drinking arsenic contaminated water knowingly because they have no other source of clean drinking water as their government try to come up with a cost-effective measure that would remove/filter the arsenic to acceptable levels. And in the long run find effective ways to deal with the effects of drinking arsenic for an extended amount of time.

Other health effects such as hypertension, diabetes, adverse reproductive effects, respiratory effects, skin lesions, and cognitive effects may be present but further studies will need to be performed to be conclusive. Concern over the potential effects of long-term, chronic exposure to arsenic in drinking water the U.S. Environmental Protection Agency (EPA)was prompted to reduce the drinking water standard for arsenic which has lead to many processes for the filtering of arsenic.  

Currently, there are many processes that allow engineers to reduce the level of arsenic in water, which includes but are not limited to: ion exchange, filtration, reverse osmosis and an innovative way called point of use, point of source/entry.