Advantages And Disadvantages Of Arsenic

.1 Occurrence of arsenic in the environment and sources of arsenic

Arsenic, a common element in nature, is a naturally occurring contaminant of drinking water and can be found in the earth’s crust, ground and marine water and in the organic world as well. It is found in groundwater as a result of the strong influence of water-rock interactions and the greater tendency in aquifers for the physical and Arsenic occurs in two primary forms such as organic and inorganic. Organic species, predominantly found in foodstuffs e.g. shellfish, are produced mostly in surface waters by biological activity but are rarely quantitatively important. Inorganic arsenic, on the other hand, occurs in two valence states, arsenite (AsO33-) and arsenate (AsO43-), which

3.2.3.1 Advantages

 Shown effective in laboratory studies in industrialized and developing countries.

 In most cases the bed can be regenerated.

 Arsenic can be removed up to 90-98%[4]

3.2.3.2 Disadvantages

 Simple media are inexpensive, but advanced media can be relatively expensive.

 Need to be evaluated under different environmental conditions, and in field settings.

 Non removal of As(III) hence oxidation is required.[4]

3.2.4 Physical removal

Some synthetic membranes are permeable to certain dissolved compounds but exclude others. Because of their selective permeability for different compounds, such membranes can act as a molecular filter to remove dissolved arsenic, along with many other dissolved and particulate compounds. High pressures are required to cause water to pass across the membrane from a concentrated to dilute solution. For this reason membrane separation is addressed as a pressure driven process.

Following physical processes are used

 Reverse Osmosis

 Micro-filtration

 Nano