Note for Environmental Studies and Health Care - ESHC by Manas Asha

Topics ( 5 )

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1 Hazardous Waste Management Hazardous Waste Management Due to progress in science and technology, a numbers of hazardous substances are being generated from different sources. According to WHO, USEPA, World Bank, in 1987, any waste excluding domestic and radioactive waste, because of its physical, chemical and infectious characteristics, some of these substances are potentially hazardous to human health and environment immediately or over later. And cause health injury, permanent disability, fatality, mortality, when it improperly treated, stored, transferred and disposed. Hazardous potential of many of these substances are still not known. This chapter deals with hazardous waste characteristic, treatment, disposal and management. According to MoEF, Hazardous Waste handle, storage and management Rule, 1989, amendment in 2003 and 2009. The six characteristic of hazardous waste are I , R , C , T , Acute Toxic and Infectious in nature. 1. Ignitability : It catch fire easily. When it has > 24 % organic matter and flash point < 60 oC. Ex : petroleum product. 2. Corrosivity : A hazardous waste show corrosivity, if it has the has pH ≤ 2 or ≥ 12.5 . It can corrode steel > 6.35 mm per year at temperature of 55 oC. Ex : Acid – HCL, H2SO4, HNO3, HF and Base – NaOH, KOH etc. 3. Reactivity : These waste strongly or violently react with water and other chemical. These are unstable and undergo violent changes. It is explosive, when mix with air. Ex : Cyanide, sulphide bearing waste if pH 2.0 to 12.5 and generate toxic gas and vapour. Ammonium Nitrate, Tri Nitro Toluene (TNT) and other explosive. 4. Toxicity : It is toxic and dangerous to living things when ingested or absorbed. It causes poisoning, cancer, fatality, carcinogenic and mutagenic disorder etc. Ex : Heavy metal like Cd, Cr, Pb, Hg and Chloro Organic pesticides etc. 5. Acute Toxicity : It is serious degree of toxicity, which can cause fatality, serious injury, carcinogenic and mutagenic disorders etc. Ex : Halogenated Benzene, Halogenated phenol, pesticide etc. 6. Infectious Properties : When contact with pathogenic microbes, toxin, which cause disease in human and animal. Classification of Hazardous Waste : Chemical : The excess use of chemical for industrial and agricultural purposes is the main source of chemical pollutant. These are highly toxic to living organism and environment. Note prepared by – Manas Ranjan Asa , Asst. Prof., OEC , BBSR

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2 Hazardous Waste Management Industry like steel, petrochemical, non-ferrous, fertilizer, pesticide and detergent are generate toxic materials. Biological : Those waste generate from hospital, operation theaters, nursing home, clinical laboratory, biological research center etc. are called Medical Hazardous Waste or Bio – Medical Waste. These are comes under Bio – Medical Waste rule, 1998. Ex : expire or absolute medicine, infectious material like dressing cotton, pathological waste laboratory and operation theaters like, sharp and pointed items like needle and blade, biological waste from human and animal , biological waste from microbiological culture waste etc. Flammable : These may be solid, gases and liquid from organic solvent, oil, organic sludge, plasticizers etc. Explosive : These waste have high potential for hazard during collection, storage, transport and available in solid, liquid and gaseous form. Ex : weapons manufacturing source and industrial gases etc. Radioactive : The substances that are emitting ionizing radiation are defined as radioactive substance. These are hazard because of exposure, so handle with more care. It result of damage the life supporting system of living organism and contaminate air, water, land and retain over long time i.e contaminant both biotic and abiotic community. Natural sources – natural occurring isotopes, cosmic ray from outer space etc. and manmade sources – nuclear weapon, atomic reactor, fuel in nuclear power station, mining, refining of radio element and radio isotopes ( I12 , C14 , P12 ). Control of natural sources is not possible but control of artificial radioactive substance is possible by proper management. So manage (handle, storage, uses, control, dispose) are highly specialized. Source of Hazardous Waste : Automobile – Cd, Pb, Ag, Zn, used battery, lubricant, grease, oil etc. Metal fining Industry / Electro plating – Cr, Cu, Zn, Co Chemical Dye / Paint – Cr, Cu, Pb, Hg, Cd, Co, Se Leather – Cr, Organic Pharmaceutical – As, Hg, trace organic Agrochemical – Chloro Organic, Benzene, Pesticide, herbicide, Insecticide, fungicide etc. Plastic – Co, Hg, Zn Organic Textile – Cr, Cu, Organic E – Waste – Pb, Cd, Hg, Zn, Cu, Co, Se Organic Petrochemical/ Metallurgical/ Coal – Alkaline / Acid sludge with heavy metal, Cyanide, Fluoride, Phenolic waste etc. Note prepared by – Manas Ranjan Asa , Asst. Prof., OEC , BBSR

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3 Hazardous Waste Management Medical Hazardous Waste – Expired medicine, infectious material like dressing cotton, pathological waste from laboratory and operation theaters, sharp and pointed items like needle and blade etc. Household Hazardous Waste – used battery & lubricant, expire medicine, pesticide, paint, perfume etc. Management of Hazardous Waste : Generation Storage Collection & Transportation Treatment Storage Disposal Storage : In tank, metal drum, above and ground create vaults. All storage sites are designed in order to protect the environment and people from contamination of radiation. Continuous monitoring to evaluate compliance with all regulatory requirements. Collection : Collection in sealed drum or container and loaded to collection vehicle mechanically. Transportation : Guided by International regulation. For identification of hazardous waste carrying vehicle use designated colour, code and symbol. Separate collection system, transfer system and collection center for hazardous waste. Distance between collection points to treatment unit decides the types of vehicle used. For short distance – storage drum with flatbed vehicle are used. For long distance – large tank truck, rail tank car are used. Treatment of Hazardous Waste : Physical Treatment :  Filtration : Suspended hazardous waste impurities can be separated by filtration.  Flocculation : Colloidal hazardous waste impurities can be removed by particle aggregation / floc formation with optimum use of coagulant.  Sedimentation : Plane sedimentation  Centrifugation : Separation based upon variable density. Chemical Treatment : Note prepared by – Manas Ranjan Asa , Asst. Prof., OEC , BBSR

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4 Hazardous Waste Management Neutralization : Highly acidic ( < 2 ) and alkaline ( > 12.5 ) waste cause corrosive characteristics. This can be neutralize ( bring them into normal pH ), by addition of lime and acid. And convert them for non-hazardous. Detoxification : Oxidation / reduction reaction convert the hazardous waste to non – hazardous waste and reduce / minimize the toxic effect and convert soluble impurities into insoluble precipitate. Cr 6+ from electroplating effluent is reducing to Cr Cr 3+ are insoluble, less toxic and more easily precipitate then Cr 6+. 3SO2 + 3 H2O 2CrO3 + 3 H2SO3 Cr 6+ (soluble) → 3+ by using a reducing agent such as SO2. As 3H2SO3 Cr2 (SO4)3 + 3H2O Cr 3+ ( Ion is insoluble ) Cyanide waste found in metal finishing industry. These are oxidized to less toxic cyanate using alkaline chlorination. Further chlorination oxidizes the cyanate to CO2 and N2. NaCN + Cl2 + 2NaOH NaCNO + 2 NaCl + H2O 2NaCNO + 3Cl2 + 4NaOH CN - → 2CO2 + N2 + 6NaCl + 2H2O CO2 + N2 By Oxidation : Benzene, phenol, cyanide, As, Fe, Mn and organic By Reduction : Cr+6, Hg, Pb, Ag, PCB and unsaturated Hydrocarbon. Thermal Treatment : Incineration : Incineration is the process of burning / oxidation of hazardous waste with high temperature in an oxygen rich environment / with adequate supply of O2 / air. High temperature break the complex bond of undesirable harmful substances and convert them into harmless. Here oxygen oxidizes harmful substances into harmless. At high temperature, toxic organic waste bond are broken to produce stable end product like CO2 , H2O etc. In this process some toxic gases and dust are generated. So every incinerator process requires adequate air pollution control system. Organic waste → CO2 + H2O + other gases In this respect incineration is a destructive process. The most importance criteria for hazardous waste incinerators are the complete destruction of major hazardous compounds confining the level of air emission. This is called Destruction Removal Efficiency (DRE) – DRE = x 100 Note prepared by – Manas Ranjan Asa , Asst. Prof., OEC , BBSR