Environmental Pollution - Lecture Notes

ENVIRONMENTAL POLLUTION Environmental pollution is the result of the urban - the industrial-technological revolution and the speedy exploitation of every bit of natural resources.The term environment, as far as pollution is concerned, includes the air, the water, the soil, the noise, the building, the landscapes,the Wiccans, and the lakes. the rivers, the park,the vehicles and many other things.Pollution, is generally defined as Theaddition of the consistments to water,airor land, which aciversely aller thenatural quality of the environmentThus, Environmental pollution is theunfarmsable alternation of our surroundingwholly or largely as a by- product ofman's actions through direct a indirecteffects of changes in the energy pattern,radiation levels, chemical and physicalconstitution and absundance of organisms SOIL POLLUTIONDumping of industrial, and municipal wastecauses toxic substances to be leachedand seep into the soil and affects theground water course. Modern agriculturalpractices introduce numerous pesticides,fungicides, bactericides, insecticides, biocides,fertilizers and manures, resulting in severebiological and chemical contamination oflandsoil gets heavily polluted day by day bhazardous organisms chain, result air thatchemicals with themicro - enter our food anwater, which are consequently ingested by masoil pollution mainly results from thefollowing sources :-1.Industrial wastes ,2Urban wastes3Radioactive pollutants4.chimical and metallic pollutants.Agricultural practicesS6.Biological agents7.MiningQResistant Objects9.soil sediments Pollution byFERTILIZERSNow- a- days agricultural practices relyheavily on artificial fertilizers, whichgenerally contain one or more of theplant nutrients i.e. nitrogen, phosphorus andpotassium. Critical pollution problems arisemainly from their excessive application rateAlthough the fertilizers are used to clarifyand fortify the soil, yet they also contaminathe soil with their impurities. when thefertilizers are contaminated with other synthetorganic pollutants, the water present in thesoil may also get polluted Generally, fertilizeare retained by the soil and crop efficientsbut there are some possibilities for thenitrates to be washed out due to negligencein applying fertilizers to arable landsparticularly in a wet spring These nitratcause several undesirable effects on thewater quality of lowland lakes orrivers creating numerous health hazardsAccording to a recent study, a nitratein the drinking water abovepermissible limit may cause acute respiratory disorder in children. Accordingto WHO, the permissible limit for nitratesin drinking water is only 50 mg ions perlitreHigher intake of nitrates also causes theproduction of free radicals of nitric oxide,and oxygen. Free radicals of nitric oxidehave a great affirity to haemoglobin, is anthe oxygen carrying capacity of bloodfurther reduced Free radicals of nitricoxide and oxygen cause dilation of bloodvessels along with damage to the cellsNormal functioning of the lung dependsupon the balance between the dilation anoconstriction activity with excess nitrate inwater, the process is disturbed and createsconditions of infection of the respiratorytract However, it is not only theincreazing utilization of fertilizers, but alsoescalated production which creates soil pollutichazards The green revolution has boostedagricultural productionThe green revolution was mainly caused throwapplic ation of chemical fertilizers to the soilin large quantities to increase the yield ofmiracle varieties of cereals, mainly wheat, andrice, forming bulk of our grain production PESTICIDESThe pesticides are used in houses and fieldsto eradicate kill pests and protect stored food grainThey many disease transmitting insects,rodents, snails etc. and hence they are immenselybeneficial to man, Pesticides generally belongto two major groups.1.Chlorinated hydrocarbon insecticides2.organophosphoris insecticides.The chlorinated hydrocarbon insecticides aresynthetic chemicals which are characterizedby the presence of carbon, chlorine, hydrogand cyclic carbon chains including benzenerings. The three most common chlorinate andhydrocarbon insecticides are DDT, BHCcyclodiene.The organophosphorus insecticides are synthetichemicals which are somecommon areexamples Tetramethyl forms of Pyrophosph phosphor etc(TMPP), Parathion, Malathion, coumaphosThey pollute air and water and finallyreach man and animals through skin,respiratory system and gastro intestinaltract The herbicides (weedicides) are chemicals usedfor the control of weeds and other unwantedplants Depending on the mode The of action,herbicides are of two types firstcategory includes those herbicides which intereswith the photo synthetic activity, thus causingthe plant to die from lack of energyMonuron and Simazin are the examples ofthis kind of hurbicides. The second categorof herbicides includes those herbicides whoseaction is not clearly under stood. Examplesof this kind of herbicides are 2, 4- dichlosphenoxy acitic acid (2-4 D) and 2, 4, 5 trichlorophenoxy acetic acid (2,4,5-T)Thus, herbicides can modify plant communitwhich in turn affect herbivores and thencarnivores.The other biocides like fungicides are used tokill the disease causing fungi. They aredangerous to the host if used in largeconcentrations. The bactericides are used tokill bacteria while nematicides are used tokill nemato des. Rodenticides which are usedto kill rodents may be left to rot butthey cause pollution of soil becausethey are non- biodegradable 7The chlorinated hydrocarbon insecticides causemutations of DNA molicules in man andlivestock. They are mainly central Nervoussystem (CNS) poisons and elicit a variety ofCNS symptoms in man. They also affect thevital organs of the body. A number ofdegenerative alterations are caused by theseinsecticides particularly in the liver andkidney. DDT is carcinogenic to man, if itsaccumulation in human tissues exceeds acertain limit. Both DDT and BHC leave a lotresidual toxicity in vegetables, grains and planand hence have a chance of causingcancer.The remnants of pesti cides get absorbedby soil particles which may contaminate residu rootcrops grown in soils. Thise pesticidecoexist within biological system with other forof life. Residual herbicides which are appliesto the soil at the time of seeding remainactive for several weeks and prevent the thegrowth of weeds in competition withemerging germinating uop. 8PLASTICSDelhi's garbage consists of upto 30% plasticbags, which is almost the highest in thecountry The plastic bag left by touristsin Shimla have stunted grass growth andhas led to soil erosion. Sikkin, Manali,Nainital and other hill areas also facesimilar problems.Say no to plastic bags and yes to cloth,jute and paper bags, because plastic bagsare not just dangerous but lethal too. Theypollute the environment and are a healthhazard, because of the following reasons.(a)Plastic bags are non- biodegradable as they cannbe destroyed and on burning plastic bags emittoxic gases such as dioxins, inhalation of whichleads to lung infection, respiratory problems, bronchand even cancer.(b)Plastic bags contain harmful chemical dyes, andpigments used for colowing bags contaminate the anfood, causing food poisoning, kidney damagebone abnormality specially in children(c)Plastic sags choke drainage system and chokeddrains become an easy breeding ground formosquitoes, flies and bacteria. .118 9:(d)Plastic bags prevent the growth of plants. Beingnon- biodegradable plastic bags affect soilfertility and water perlocation in the ground(e)Plastic sags kill animals, because theyobstruct the intestines leading to a painfuland slow death of animals.Phthalates are the chemicals added to plastics,particularly polyvinyl chloride (PVC), to softerthem They are also added to soaps asemulsifiers and in cosmetics to carry thefragrance. They have been linked to reproductshealth effects including reduced fertility,miscarriage, birth defects, abnormalities etc.They have also been found to cause liver andkidney cancerMETALSThe toxic metals may be absorbed by plants growin contaminated soil which then accumulate to inanimals eating those plants perhaps metals reaching becomechronic toxic levels. Most heavy more.quite insoluble in soil at pH than 6 or other heavemetals, is a frequent containant: also solublCadmium, being highly soluble other metasuch as Ni, cu, Mo and Zn are 0but to a lesser extent. Research has shown anincreasing rate of maternal mortality kidneyand liver related diseases, birth abnormalizieand cancer. A high percentage of children bornwith asphyxia. This is because of the factthat high levels of heavy metals like Mn, Pb,Sr, col and other metals have been foundin the placenta and in the blood.The problem is largely the result of exposureto toxic substances such as heavy metalsand pesticide residues. Chernabyle, Hiroshimaand Nagasaki are examples of disasters due tometalsSynthetic chemical and fertilizers are asource of trace metals which are added tothe soil either deliberately or as animpurity. for example, As, Pb and Col- thecommon trace metals in rock phosphate,also occur in superphosphate fertilizersJoxic selenium species get less readilyoxidised so it cannot be removed easily fromsoil by weathering Today various traceelements such as Fe, C6, Ni , Cu, Zn, Ba, Pb,V, Mn, Ni, As, Hg, Mo and Si are being addedto the soil in one or the other form.Mn and Fe oxides have a tendency toconcentrate trace metals by isomarphous 11replacement of ionsPresence of high levels of Na, Mg and Kcauses calcium deficiency in soil Magnisideficiency in soil is caused due to highconcentrations of Ca, Na and K, which areadded as artificial fertilizers. Excess ofsulphur in soil may be absorbid byplant leaves as sulphur dioxide injuringplant tissues Although Mg, Fe, Zn and Vpresent at high levels pose effectsmay be involved in photo synthesis, lethal but ifon crop production Metallic contanionation theof soil is considered to beindestructible poison and they affect theproduction of atmospheric oxygen as well asliving seingsThe crops most likely to have highconcentration of metals when grown onsludge treated soils are largely vegetablessuch as spinach, whireas the least affected andfood products include grains, fruitsvegetables. WASTE TREATMENTSolid Waste can be classified as :-1.Domestic Wastes - These include wastes fromhousehold preparation, cooking and servingof food, waste paper, cloth, rags andplastics etc.2Municipal Solid Wastes (MSW) - These wastesinclude garbage and rubbish formhouseholds, hotels, offices , markets / etc. andalso the street refuse such as streetsweepings, dirt, leaves, contents of litter receptor3.Industrial Wastes These wastes includes procesand non- process wastes.4.Agricultural Wastes - These wastes resultfrom farms, feed lots and livestock yardsincluding residues, paddy husk, house tobacco wastes, and corn5Biomedical Wastes (BMW) - BMW includesslaughter manures etcpathological and surgical wastes6.other wastes.Waste treatment may be categorisedand studied under the followingheads :- 13MUNICIPAL SOLID WASTE TREATMENTThis treatment can be done in thefollowing ways. -1.>DUMPINGopen dumping of solid wastes is practised inIndia because it is cheap and requires noplanning. Generally, the low- lying areas andoutskirts of the towns and cities areused for this purpose. This open dumpscause public health problems by encouragirthe breeding of flies, mosquitoes, ratsand other pests. They also become a sourceof objectionable odours and cause airpollution when the wastes are burned.2.>COMPOSTINGcomposting is the acrobic and thermophilicdecomposition of organic matter in therefusi by micro-ongarians primarilybacteria, fungi, insects and warms.C6H12O6 + 6 O26 CO2 + 6420 + 674 kcal.Microbes already present in the waste,stabilise the organic matter in the waste toproduce a soil conditioner Bacteria the predominateat all stages, fungi appears after first theweek and actinomycites assist duringfinal stages. 14SAComposting operationthe following optimum control parameters areadhered to :-PH - 4.5 - 8.5 ( PH should be below 2.5 tominimise the loss of nitrogen as ammoniMoisture- 55%Particle size- 0.63 to 2.54cmAir - 0.5-0.0m3 / day kg of volatile compost solicC to N ratio 50 : 1 / C : P ratio = 100 : /3.VERMI COMPOSTINGVermiculture or the use of earthworms is abiotechnology where the earthworms feed on anddegrade noxious elements a variety and of organic convert the waste wastes eliminate intovermicompost which has a high grade nutrientrich compost. It is very useful bio fertilizerand soil conditioner. Vermicompost enhancessoil productivity and increases crop yieldOut of 3000 species of earth worns, about385 species have been seen in India. Theuseful species are Lampito mauritii, Dichogasterboloui, Drawida Willsi etc. BhawalkarEarthworm Research Institute (BERI) developeda process for the treat ment of wastewater using this method. 16SANITARY LANDFILLSanitary landfill is an engineered operation,designed to and operated biologically accordingacceptable standards It may be definedas a method of disposing refuse on landwithout creating nuisance or hazards topublic health. The operation is carried outwithout environmental damage and inareas already spoiled or in need ofrestorationThe end products of this process areCO2, CHy and a little amount of H2S,NH3 and H2O.5.INCINERATIONIncineration involves burning of solid wastesat high temperatures, leftover ashes, glassand metals. The unburnt combustibles amountto 25% of the original waste. The residuemust still be disposed of in somemanner. Incineration is performed whensuitable site for land filling is notavailable within economic limits. Twotypes of incinerators are used- -Batch Type incinerator - It is manually stokedand has small rated capacitycontinuous Type incinerators- - These incinerators 18are equipped with large storage sins, automaticfeed happers, various types of moving gratesand ash discharging systemsThe modern municipal incinerators areof continuously burning type6.AUTOTHERMIC INCINERATION OF DEWATERED SLUDGEIncineration of a mechanically dewateredsludge is an autothesmic process (conductingthe process of thermal drying and incinerationwithout additional consumption of fuel)maybe achieved when the moisture of thesludge is 60-65% The process is extremelyuseful when toxic substances in the sludgeprevents its use as a fertilizer or in amunicipal landfill.INDUSTRIAL SOLID WASTE TREATMENTThis treatment may be done in thefollowing ways- -1.INCINERATIONIndustrial solid wastes that are incineratedare mostly cellulose type and more oftenindustries have to handle certain kinds ofchemical wastes in the form of solids or 19sludges. In chemical process industries, incinerat-ion is most frequently used to disposeof carry and gummy petroleum andplastic intermediate wastes and generalrefuse Waste combustibility is animportant factor in determining the applicableincineration process.2.PYROLYSISThe chemical energy of some organic wastes canbe recovered by distructive distillation orpyrolysis of the solid waste. The combustibleconstituents of the solid wastes are heatedin a special retort i.e pyrolysis reactor at1000°c in a low- oxygen or an oxygen-freeenvironment This is an endothermic processand thus differs from the conventionalincineration Pyrolysis of the solid wasteyields the following components1.Jar or oil phase containing acetone, aceticacid, and methanol etc .2.Gaseous phase containing H2, CHy, CO and co,ltc 23.Solid phase containing pure carbon charand inert materials like glass, rock, metals.3.VITRIFICATIONThe recent technique in situ vitrification 20aims at converting the solid wastes into asort of glass. In this, electrodes are insertedinto the waste heap and a very powerfulelectric current is passed through it. the strongheat so produced melts glass, plastic, muck, mudand other wastes into glass like solid. It cowbe dumped anywhere as it leaches very little.However, in this method care is taken toprevent mingling of radio wastes with otherorganic compounds.SOLID WASTE MANAGEMENT BY BIOTECHNOLOGYMicro-Organisms like bacteria and fungi playa vital role in decomposing complex organicwastes and it may be possible to recoverresources by them. It is also possible toproduce such microbes by genetic engineeringThis novel development is the isolation ofbacteria which can dissociate polychlorinatedbiphenyls (PCBS)New biodegradable plastics are importantsteps towards solving solid waste problemsin respect to plastic wasts Photo degradableplastics have now been developed whichdissociate on exposure to sunlight 22torch, a quenching or scrubber unit and twochambers It can treat about 20 kg of medicalwaste per hourBMW from such hospitals which do not havefacilities for incineration or pyrolysis aresegregated, packed in specially coded and labelledcontainers and transported to a place where suchfacilities exist.Control of BMWOn- site handling of BMW and their off sitedisposal are considered as the responsibilityof the waste generators themselves In countrieslike USA and canada, BMW are controlled asper USEPA'S 1995 guidelines and India haspassed amended Biomedical waste (Managementand Handling) Act in June 2000.RECYCLING, RECOVERY AND REUSESolid wastes contain significant amount of valuablematerials like paper, plastics metal and glass,which if they are recovered and reused, wouldreduce the volume of wastes to be collected andat the same time would yield significant salvageand resafe income