Arsenic

Arsenic as a water pollutant

Arsenic can be found naturally in certain soils. When arsenic comes in contact with groundwater it may end up in water, as well. Arsenic is a metalloid, which basically means that it has the properties of both metal and non-metal. As a compound, arsenic may be toxic. That is why it is commonly applied in rat poison.
Arsenic ends up in the environment through industrial production of copper, lead and zinc, and through insecticide applications on farmland. Additionally, it is an ingredient of wood preservatives. A long-term uptake of large quantities of drinking water that contains arsenic may cause skin conditions and certain cancers, such as skin cancer and lung cancer. Water purification is very important when arsenic is present.

Which arsenic concentrations can be in drinking water?

The WHO (World Health Organization) advices a maximum concentration of 10 ppb. Although arsenic may be found in surface water, groundwater is the main source of arsenic in water. Consequentially, concentrations above 10 ppb may be found naturally in groundwater.
In groundwater arsenic exists as water-insoluble anorganic arsenic AS-V anions or AS-III molecules.
In Bangladesh groundwater concentrations of arsenic may exceeds 100 ppb on some locations.

How can we remove arsenic from water?

Arsenic can be removed from water in various ways. Examples of water purification techniques that may be applied are iron and aluminum coagulation, activated alumina adsorption, ion exchange and membrane filtration. AS-V can be removed easier than AS-III. AS-III can be removed when it is pre-oxidised to AS-V.

When you need water analyses for arsenic or you need some advice on water purification techniques for arsenic removal, please feel free to contact our specialists. Lenntech can provide you with small and handy arsenic test-kits.