Mitigation and Remedy of Groundwater Arsenic Menace in India

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