Mitigation and Remedy of Groundwater Arsenic Menace in India

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Mitigation and Remedy of Groundwater Arsenic Menace in India : A Vision DocumentAlthough, As (III) can be oxidized to As (V) by various methods like oxygen, catalyticoxidation, UV irradiation, chemicals (free chlorine, hypochlorite, bleaching powder, ozone,permanganate, hydrogen peroxide, etc.) and sun light , air oxidation of arsenic is very slow andcan take weeks for oxidation (Pierce and Moore, 1982). Chlorine dioxide and monochloramineare ineffective in oxidizing As (III) to As (V). Ultraviolet (UV) light, by itself, is also ineffective.However, if the water is spiked with sulfite, UV photo-oxidation shows promise for As (III)conversion (Ghurye and Clifford, 2001). Based on these considerations, only chlorine,permanganate and ozone are effective oxidizing agents for oxidizing As (III) to As (V), overwide range of working condition.5.2 Conventional TechnologiesThe arsenic removal devices developed by different agencies, and applied to treat forremoving arsenic from arsenic contaminated groundwater with some degree of success aregiven in Table 5.1 and shown in Figure 5.1.Table 5.1: Arsenic removal devices applied for removal of arsenic from contaminated groundwaterName of thedeviceRPM/ AlcanAAFS -50 mediaby RPMMarketing Pvt.Ltd., KolkataBucket of Resins(BOR) of WaterSystemsInternational ,USA byHarmonite Impex(Pvt.) Ltd.,Kolkata.Granular FerricHydroxide (GFH)of Pal Trockner(P) Ltd., Kolkata– a GermanTechnologyArsenic RemovalPlant by OxideIndia (Catalysts)Pvt. Ltd,DurgapurADHIACON :AFDWS 2000 –Arsenic RemovalPlantOperationprincipleAdsorptionFilter media Price System PerformanceActivatedAlumina +AAFS-50.Ion Exchange Bucket ofResinsAdsorptionAdsorptionCatalyticprecipitation/ElectronExchangeGranular FerricHydroxide(GFH)ActivatedAlumina , AS-37Rs.44,300 +Rs.20,000 percharge.Rs.92,300 +Rs.39,000 perchargeRs. 74,100 +Rs.25,000 perchargeRs. 47,300 +Rs.14,400 perchargeThe purification system consists oftwo containers; one to remove mudand suspended particles and other oneconsists of AAFS-50 media to removearsenic and heavy metalThe unit ‘BOR’ is a rectangularcontainer of 40 inches long, 26 incheswide, and 40 inches height attached toa tube well hand pump. The containerconsists of 3 cylinders to processvarious phases of oxidation andabsorption. The system has provisionof backwashing depending on contentof arsenic and iron.The system is based on GFH and userfriendly. It does not requirecomplicated dosing of chemicals andclaimed to be non-toxic and nonhazardous.The system is made of Stainless Steel,AISI-304. It has a back wash systemand removal process is based onadsorption with special grade ofActivated Alumina. It also removesheavy metal, Fluoride, Nitrate, Greaseand Oils.AFDWS - 2000 Rs. 75,000 The unit is fitted with lifted head ofhand pump. It has basically threechambers - primary, secondary andMicro-filtration chambers. The wateris pumped through 3 way valve toprimary chamber where raw waterfi h h i lAlthough design andmodel is user friendlybut has mixed feelingson performance.Media replacementhad showed lesserefficiency than theoriginal.Field performance ofthe system was belowsatisfactory level andinconsistent.Satisfactoryperformance, and lesscost on operation andmaintenance.Satisfactoryperformance in all 50installed places.Company guarantees 2years O & M, trainingincludingperformance.Field performance ofthe system was belowsatisfactory level.NIH & CGWB 79
Technological Options and Arsenic Removal TechnologiesHandpumpAttached ArsenicRemoval Plant byAIIH&PH,KolkataIONOCHEM,KolkataApyron ArsenicTreatment Unitsby ApyronTechnologies (P)Ltd. Representingof ApyronTechnologies Inc.,USAPublic HealthEngineeringDepartment, Govt.of West Bengal80Oxidation +Coagulation +Flocculation/Precipitationand filtrationIon exchangeAdsorptionChlorinatingagent (BP) +Ferric AlumFerricHydroxideAqua Bind(ActivatedAlumina + )Adsorption Red Hematite(Fe 2O 3) lumps +quartz + sandactivatedaluminaRs. 35,000 +periodicchemicalreagentsRs. 39,000Rs. 80,000 +Rs. 15,000per chargeRs. 27,000p yfirst passes through a coarse stainlesssteel strainer and then comes incontact with filter media in whichcatalytic precipitation takes place.The purified water from the primarychamber goes to secondary chamberfor downward filtration. Fromsecondary chambers water passesthrough micro-filtration chamber andthen purified water goes through threeway valve at the outlet.The system is comprised of a nonmechanicalclari-flocculator and upflowgravel filter and it has threechambers. Bleaching powder andalum are the two chemicals used forremoval of arsenic. In the firstchamber bleaching powder solution isadded in appropriate dosage withpumped water where they arethoroughly mixed in presence ofbaffles. The chemical mixed water isthereafter passed through secondchamber for precipitation of the flocs.The clean water is collected in thelaunder chamber. From launder wateris taken to the filter (third) chamber,from where water is allowed to flowin upward direction through gradedgravel media. The arsenic safe filteredwater is finally collected through a tapprovided in the filtered chamber.The system is comprised of one IronRemoval Filter and one Arsenic Filterand the system is fitted with HandPump The principal media is bondedcompound of Fe(OH) 3 and βFeOOH.When Hand Pump is operated, thepressurized raw water is passedinitially through iron removal filterfilled with catalytic filtering mediaand reacts with sodium arsenates andFe(OH) 2. Due to chemisorption AS isbonded with the material and Arsenicis removed.The system is comprised of anassembly of Handpump with its outletconnected to the filtering media.When the Hand Pump is operated, theraw water passes through the filtermedia where arsenic is removed andfinally treated water is collectedthrough an outlet pipe from the filtermedia. The filter media is comprisedof manganese oxide and activatedalumina. Manganese oxide convertsAs 3+ to As 5+ , which is adsorbed on thealumina media. The unit also removesiron.Removal of arsenic is accomplished in4 chambers. Groundwater isabstracted by Hand Pump and sprayinto droplets over a bed containingpacked hematite lumps (Fe 2O 3) beforesending to first chamber forsedimentation. Sediment free water isconveyed through chambers placed inseries containing red hematite lumps,Periodic daily dosingof chemical reagentsare necessary. Thesystem requiresconstant vigilance andclose monitoring andchemical dosing.Regular backwashingof iron filter isessential, whichcaused problem ofoperation andmaintenance.Otherwise, theperformance remainedsatisfactory.Showed satisfactoryperformance, treatingarsenic levels as highas 3500 ppb to a safelevel of less than 50ppb. After use, filtermedia can be disposedsafely as ordinarysanitary waste.Reported as one of thefinest performingdevises and capable toremove arsenic fromvery high level ofcontamination.However, theweakness is itsinability to produceNIH & 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 Groundwate
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Mitigation and Remedy of Groundwater Arsenic Menace in India

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