Mitigation and Remedy of Groundwater Arsenic Menace in India

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Mitigation and Remedy of Groundwater Arsenic Menace in India : A Vision DocumentThe adsorbed media rich in arsenic can also be mixed with concrete as an additionalaggregate but in a controlled proportion. Liquid wastes must have lower concentrations than thetoxicity characteristic in order for the waste to be classified as non-hazardous. The arsenictoxicity characteristic is 5.0 mg/L. Those liquid wastes that contain more than 5.0 mg/L ofarsenic would, therefore, be classified as a hazardous waste. Many of the arsenic removaltechnologies also remove other constituents and therefore the liquid waste must also beanalyzed for other substances that may be present in concentrations above their respectivetoxicity characteristics. Because of the cost implications, on-site treatment or off-site disposal ofhazardous waste is likely to be infeasible for small water systems. Indirect discharge throughsewer to treatment plants may be viable option for waste disposal. There are five realisticmethods for the disposal of arsenic wastes.5.4.1 Landfill DisposalHistorically, municipal solid waste landfills have been commonly used for the disposal ofNon-hazardous solid wastes emanating from treatment processes. However, the hazardpotential of arsenic may limit the feasibility of this alternative.Dewatered sludge and spent media can be disposed in a municipal solid waste landfill ifthe waste passes both the Paint Filter Liquids Test (PFLT) and the TCLP. The PFLT is used toverify that there is no free liquid residual associated with the waste. However, if the TCLPextract contains arsenic or any other contaminant (e.g., chromium) above the TC, the wasteresiduals must be disposed in a designated hazardous waste landfill. As such, the costs ofdisposal are relatively high. As with municipal solid waste landfill disposal, waste sludges mustnot contain free liquid residuals.5.4.2 Direct Discharge to Surface WatersDirect discharge refers to the disposal of liquid wastes to nearby surface waters, whichact to dilute and disperse the waste by-products. The primary advantage of direct discharge is toreduce capital and operations and maintenance costs due to the elimination of residualstreatment. The feasibility of this disposal method is subject to provisions of the guidelines forwaste disposal. The allowable discharge is a function of the ability of the receiving water toassimilate the arsenic without exceeding water quality criteria established under the Govt.regulations. Different water quality criteria exist depending on the classification of the receivingwater. For specific criteria, conditions and limits, the appropriate agency should be contacted,because the conditions and limits can vary according to the receiving water's particularcharacteristics.5.4.3 Indirect DischargeThe discharge of liquid wastes to a treatment plant is a potential disposal alternative. Inthis case, the wastes can be discharged to sewer systems. The arsenic limit is usually on theNIH & CGWB 99
Technological Options and Arsenic Removal Technologiesorder of 50 to 10 µg/L. The TBLLs are computed for each POTW to take into account thebackground levels of contaminants in the municipal wastewater. The background level will changebecause of the drinking water treatment process, which may lead to revised TBLLs. Therevised TBLL can be used to determine if the liquid waste stream could be discharged to thePOTW.5.4.4 Land ApplicationLand application of concentrated sludge may be allowed under certain conditionsdepending on the state law and regulations. As per USEPA guidelines, sewage sludge (alsocalled "biosolids") containing
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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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