Mitigation and Remedy of Groundwater Arsenic Menace in India

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Mitigation and Remedy of Groundwater Arsenic Menace in India : A Vision DocumentAnnexureA. Sustainability of Arsenic Removal TechnologyBased on the working principles, the Arsenic removal methods can be classified intothree categories: (i) Chemical precipitation method, (ii) Adsorption method, and (iii) Membraneseparation method. An appraisal of different treatment technologies and their effectivenessreported from laboratory testing conducted by researchers has been given through pages105-108 (Chapter-6). Among these categories, Membrane separation method by Reserveosmosis has been reported the most promising one with removal efficiency of 99% followed bythe Chemical precipitation method using Lime softening with removal efficiency of about 95%.The Chemical precipitation method by Oxidation/iron co-precipitation, has been reported to haveremoval efficiency ranges between 90 and 99 % under the controlled pH-Eh conditions and anoptimized Fe dosage. The efficiency of adsorption methods by Activated alumina or by Ionexchange have been reported ranges above 45%. The Reverse osmosis technology althoughdoes not produce toxic solid waste but requires high tech operation and maintenance, andrelatively costlier than other two methods. The oxidation/iron co-precipitation method is simple inoperation and less costly, but produces toxic solid waste and requires daily dosing of chemicals;while the adsorption method, which is less efficient and relatively costlier than the oxidation/ironco-precipitation method, also produces toxic solid waste and requires periodic replacement/regeneration of filtering media. Apparently, Lime softening and Iron co-precipitation techniquessound to be the most effective removal technologies, barring the Membrane separation method,however, the adsorption technique showed successful field performances and implications.Performances of 10 arsenic removal devices developed by different agencies, andapplied in West Bengal to treat for removing arsenic from arsenic contaminated groundwaterwith some degree of success have been given in Table 5.1 (pages 76 -77) and Fig 5.1 (pages101-102). Very few plants could show satisfactory performance at the field level, both in termsof arsenic removal efficiency and in sustainable running. The devises which have shownrelatively good performances at the field level are: Granular Ferric Hydroxide (GFH) of PalTrockner (P) Ltd., Kolkata - a German Technology; Arsenic Removal Plant by Oxide India(Catalysts) Pvt. Ltd, Durgapur; and Apyron Arsenic Treatment Units by Apyron Technologies(P) Ltd. representing Apyron Technologies. The working principles of these technologies arebased on adsorption technique. The major setbacks, with other devices remain with theoperation, maintenance, replacement and removal of used filters. The systems in which O & Mhave been linked to the responsibility of suppliers have shown satisfactory performance. It wasreported that majority of the operation and maintenance issues were related to tube wells, thathave nothing to do with the ARP or its chemical media.NIH & CGWB 181
AnnexureIt indicates that sustainability of arsenic removal devices largely relies on the operationand maintenance of the devices, the consistency of the source water quality, and theacceptability of the devices by the users and beneficiaries. A technology having simple operationand cared maintenance as well as cost effective, users and eco-friendly has the potential ofsustainability. There is, therefore, need arises for R & Ds to improve upon the existing devicesand/or develop new technologies to satisfy the conditions of eco-friendliness (less sludgeproducing/sludge free), cost effectiveness and user friendliness. In areas where populationdensity is relatively more and the area is under the grip of arsenic effect and there are limitedscope for alternate freshwater supply; arsenic removal devices, by choosing the best workingmodel among the existing devices under the public-private partnership with communityparticipation in the O and M, would be a suitable proposition to meet the demand of potablewater supply.B. Sludge managementThe arsenic removal devices, which have been implemented in the field particularly inWest Bengal, are based on the working principles of Chemical precipitation and Adsorption.Both the arsenic treatment techniques produce several different types of waste, includingsludges, brine streams, backwash slurries and spent media. Treatment of the slurry, obtainedfrom arsenic removal process (from groundwater), is essential to make the slurry arsenic free sothat it can be disposed without any hazard of the arsenic re-entering the aquifer system. Arsenicsludge management has been reported as one of the major concerns (pages 94-95, and 112-113).Even the treatment devices, which have shown relatively good performances at the field level,namely; Granular Ferric Hydroxide (GFH) of Pal Trockner (P) Ltd., Kolkata - a GermanTechnology; Arsenic Removal Plant by Oxide India (Catalysts) Pvt. Ltd, Durgapur; and ApyronArsenic Treatment Units by Apyron Technologies (P) Ltd., are also not devoid of sludgemanagement problem. How the sludge produced and/ or being produced from different arsenicremoval filters in the schemes implemented in West Bengal is disposed and managed, has notbeen clearly spelt out in any document, rather remained an unanswered question. The All IndiaInstitute of Hygiene and Public Health (AIIH&PH), Kolkata has suggested the followingmethods for arsenic rich sludge management:• Disposal in on-site sanitation pits,• Mixing with concrete in a controlled ratio,• Mixing with clay for burning for brick manufacturing.A number of studies (Rouf and Hossain, 2003; Mahzuz et al., 2009) showed that use ofarsenic contaminated sludge in proportion in making bricks nearly at 1000oC neither reduces thecompressive strength of bricks nor cause any negative effects. The studies clearly suggestedthat arsenic and iron sludge can be used as brick material. Banerjee and Chakraborty (2005)reported that stabilization process by briquette, cement-sand mortar and concrete mixing with182NIH & 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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5.2.2 Co-precipitationMitigation an
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5.8 SummaryMitigation and Remedy of
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Mitigation and Remedy of Groundwater Arsenic Menace in India

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