Mitigation and Remedy of Groundwater Arsenic Menace in India

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Mitigation and Remedy of Groundwater Arsenic Menace in India : A Vision Documentarsenic-free water sources; instead of opting exclusively for ex-situ arsenic removaltechnologies. Former case is the best option when complete understanding of the physico-chemicalprocesses and system behavior are methodically known; while the later case could beconsidered as a potential alternative when sustainable surface water and groundwater flows areensured. However, in either case, extensive feasibility studies would be necessary. Ex-situarsenic removal technologies can be a suitable option when the dimension of the problem is smalland short lived, such as the source is anthropogenic. For a large scale groundwater arsenicproblem, as in different states in the Country where demand of and dependability on groundwater resources both for drinking and irrigation water in such places are continuum, ex-situtreatment of tapped groundwater by arsenic removal technologies could merely be thought to bea stopgap arrangement to meet the requirement of drinking water to the people in the arsenicaffected area. Requirement of agricultural irrigation water in rural areas is far more than thedrinking water. Irrigation water requirement cannot be sustained by the ex-situ arsenic removaldevices. Use of arsenic contaminated groundwater in agriculture has far reaching consequencesin terms of contamination through food chain and environmental aspects. Further, in ex-situtreatment technologies another additional problem is arsenic sludge management. The keyissues thus emanate as: whether to adopt strategy for in-situ remediation of arsenic fromsoil-water system, or switching over to alternate surface water-groundwater managementstrategies letting remediation of arsenic groundwater menace undisturbed in its existing state-ofaffairs,or to adopt mixed management strategies such as; supply of drinking water througharsenic removal technologies and irrigation water through conjunctive use of surface water andfresh aquifer tapping? To ensure non-hazardous supply of drinking and irrigation water to thepeople in the arsenic affected areas, a suitable water management strategy on scientific footingsneeds to be evolved.If it is considered that arsenic removal technologies can be one of the technologicaloptions to ensure supply of drinking water in the arsenic affected areas, the questions generallyraised are: sustainability of the technologies in terms of cost, O & M, and efficiency. Most of theexisting devices showed unsatisfactory results in terms of cost (total and per capita), operationand maintenance and expected sustainability. Although a remarkable technological developmentin arsenic removal processes has taken place during last few years, however, very few in whichO & M has been taken care, could show potential field satisfaction. The technologies and itsfield applications, which could prove satisfactory results, can be thought for promotion withimprovisation for long term sustainability. One should also realize that arsenic mitigation strategyis location specific. A method suitable for a specific area can not be generalized for the otheraffected regions due to i) geographical and geomorphological variations, and ii) differentsocio-economic and literacy conditions of people. Therefore, a considerable R & D is necessaryto evolve eco-friendly, cost effective and user friendly arsenic removal technology. Acomparison of different arsenic removal processes is shown in Table 5.2.NIH & CGWB 103
Technological Options and Arsenic Removal TechnologiesTable 5.2: Comparison of conventional arsenic removal technologiesTechnologies Advantages DisadvantagesOxidation/Precipitation:- Air Oxidation- Chemical oxidationCoagulation/Co-precipitation:- Alum Coagulation- Iron CoagulationSorption Techniques:- Activated Alumina- Iron Coated Sand- Ion Exchange Resin- Other SorbentsMembrane Techniques:- Nanofiltration- Reverse osmosis- Electrodialysis- Relatively simple, lowcostbut slow process- Relatively simple andrapid process- Oxidizes other impuritiesand kills microbes- Relatively low capital cost- Relatively simple operation- Common Chemicalsavailable- Relatively well known andcommercially available- Well defined technique- Plenty possibilities andscope of development- Well defined and highremoval efficiency- No toxic solid wastesproduced- Capable of removal ofother contaminants- The processes removeonly a part of arsenic- Produces toxic sludges- Low removal of As(III)- Pre-oxidation required- Produces toxic solid waste- Replacement/regenerationrequired- High tech operation andmaintenance- Relatively high cost- Very high capital andrunning cost- High tech operation andmaintenance- Toxic wastewater produced104NIH & CGWB
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ACKNOWLEDGEMENTThe Government of In
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nearly 33 villages in 4 districts i
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(iii) Whether ex-situ removal techn
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6.4 Experiences during Arsenic Remo
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List of FiguresFigure no. Figure ca
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List of TablesTable no. Table Capti
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Mitigation and Remedy of Groundwater Arsenic Menace in India

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