IITB Arsenic Filter for Arsenic, Iron and Phosphate removal from groundwater Prof. Sanjeev Chaudhari Centre for Environmental Science and Engineering Indian Institute of Technology, Bombay

Background Groundwater – primary source of drinking water in many states in India Groundwater aquifers in Ganga-Meghna-Brahmaputra plain contain Arsenic Arsenic may get mobilized along with iron, under oxygen- deficient conditions. Organic pollution of groundwater is responsible for oxygen deficiency (reducing conditions). Presence of Arsenic is well reported in West Bengal and Bangladesh Recent occurrences reported in Uttar Pradesh, Bihar, Assam, Punjab, Haryana 2

Background Nearly 500 million are at risk Consumption of arsenic contaminated water causes cancer, gastrointestinal problems, cardio-vascular diseases, skin pigmentation Ground water mainly contains As(III) + As(V), it is easier to remove As(V), thus oxidation of As(III) to As(V) is essential 3

Available technologies Permissible limit for As in India = 10 µg/l No existing technology claims to reach 10 ppb consistently. Literature suggests that Fe/As > 250 required to achieve arsenic less than 10 µg/L in the absence of phosphate. Thus, to remove 500 µg/L of Arsenic, Fe required is 125mg/L, which is likely to produce significant sludge. Department of Science and Technology, Govt. of India funded a project for the development of community scale arsenic removal plants using no electricity. Lab scale experiments were carried out using ZVI and based on the results a community scale arsenic removal unit was conceptualized. 4

Fe(II ) In bulk phase (no HFO) On the HFO-H 2 O interface Fe(II) 2Fe(II) Fe(II) DO As(III) HFO Fe(II) DO As(III) As(V) HFO Fe(IV) Fe(III) DO As(V) HFO DO Fe(IV) DO HFO Fe(IV) As(IV) Reactions in the bulk phase have more wastage of oxidant radical Fe(II) DO As(III) Fe(II) Fe(IV) High HFO interface for adsorption of reactants would lead to lesser wastage of oxidising radicals and hence better oxidation and removal of As(III) 2Fe(II) Wastage of ferrate 5

Arsenic concentration (µg/l) After filtrationIn aqueous phase Sampl- ing vol. As (tot) As (V)As (tot)As (V)  Arsenic conc. in treated water from filter column achieved was 5 µg/l.  In conventional method, to reach 10 µg/l from initial of 1000 µg/l, iron dose required is 250 mg/L This shows that almost any conc. of As present in groundwater water can be treated if 5mg/L Fe is present.Experiment Iron conc (mg/L) Arsenic conc (µg/l) 6

Schematic of IITB Arsenic Filter 7

Performance of IITB Arsenic filters LocationDistrict Depth of tubewell (m) Date of installation No. of families using the filter Mean Arsenic conc. in raw water (µg/l) Final Arsenic conc. (µg/l) ShikariparaNadia50Jan SonakhaliNadia33Oct PolasiNorth 24 Paraganas 40Oct GhanguriaNadia52.5Feb Apart from this, 48 more IITB Arsenic filters were installed in Uttar Pradesh (20 nos.), Bihar (20 nos.), Assam (4 nos.) and West Bengal (4 nos. more ). 8 Monitoring data during July-2010 to December-2012

Highlights of IITB Arsenic Filter Fe/As ratio required is 10-15, thus, in most of the places, Iron present in groundwater is enough. Less sludge production. Uses only iron nails, gravel, plastic buckets and PVC pipes for construction. Electricity not required. Maintenance easy and can be done by local people Washing of iron nails twice a month Cleaning of top 30 cm of filter media once a month Cost of unit – Rs 60,000 – 75,000 Cost of delivered water – Rs. 3.3 per cubic meter Thus it is felt that the technology of IITB Arsenic filter is suitable for rural India 9

Thank you 10