Arsenic Crisis In Indian Subcontinent: An Indigenous Solution
Arup K. SenGupta Department of Civil and Environmental Engineering, LEHIGH UNIVERSITY, Bethlehem, PA 18015, U.S.A.
- The entire operation is manual and does not require any electricity. The arsenic removal columns are installed at the existing tube wells with hand pumps.
- Activated alumina(AA) which selectively removes dissolved arsenic from groundwater without changing its composition is the primary adsorbent used in the column and readily available from a company in Durgapur, West Bengal.
- Some of the latest installations contain hybrid polymeric sorbent known as HAIX developed at Lehigh University, that selectively remove arsenic from background of other species of ground water
- Both AA and HAIX are amenable to efficient regeneration and can be used for 10 to 15 cycles
- The unit does not warrant any chemical addition or sophisticated control. All one needs to do are open a valve, operate the hand pump and then collect essentially arsenic free water in a container. Regardless of the extent of contamination in well water, the arsenic concentration in treated water will consistently be less than twenty parts per billion - the standard set by World Health Organisation for drinking water.
- The regeneration of the unit with caustic soda is required about once in a year. During regeneration, the entire amount of arsenic removed can be easily converted into less than two liters of sludge and retained at the top of a well aerated coarse sand filter. To put a quantitative perspective, a 4ft by 3ft by 6ft pit is large enough to store the entire amount of arsenic laden sludge for over 10 years. The method of disposal/ containment of arsenic laden waste in a well ventilated pit is scientifically sound without further possibility of arsenic leaching.
- Upon installation of an arsenic removal unit, a villager’s committee is set up to maintain daily backwashing operation and periodical monitoring of arsenic concentrations. Economic sustenance comes through realization of water tariff per month which is about Rs.15 (less than 50 US Cents) per family.