What Are The Mechanisms Of Ozone Depletion Environmental Sciences Essay

The mechanism of planetary heating can be described by the Greenhouse consequence ; by which, solar radiation enters through the Earth ‘s ambiance and is retained, ensuing in increased temperatures. Solar radiation come ining the Earth ‘s ambiance is partly absorbed by the Earth ‘s surface and partly re-radiated back into infinite. However, holding lost energy to the Earth ‘s surface, the infrared radiation is of an increased wavelength and is accordingly absorbed by certain gasses ( nursery gasses ) in the Earth ‘s ambiance. This consequences in the radiation being recycled within the Earth ‘s ambiance, taking to an increased mean temperature of the Earth ‘s close surface air and oceans.

Ozone depletion is a consequence of the catalysed reactions between ozone and atomic Cl or Br. Chlorofluorocarbons ( CFC ) and bromofluorocarbons have the greatest ozone consuming possible as they form atomic Cl and Br upon photodissociation.

Carbon dioxide, methane and azotic oxide can be considered to hold the greatest planetary warming possible due to their copiousness. From these gasses, azotic oxide is 310 times more effectual in absorbing radiation than C dioxide, and methane is 21 times more effectual than C dioxide.

What is the difference between ‘winter ‘ and ‘summer ‘ smog? Explain the mechanism by which they are generated.

Winter and summer smog can be differentiated by their components and therefore their environmental impacts. Winter smog is made up of sulfur dioxide, partly oxidised organics and particulate affair ( PM ) , the concentrations of which are typically increased in winter months due to increased warming from sulfur rich dodo fuels such as coal and oil. It is besides referred to as ‘reducing ‘ smog. These pollutants can impact the respiratory system and signifier secondary pollutants. Sulphur dioxide can organize acerb rain from oxidization catalysed by PM or free groups of O and N.

Summer, or ‘photochemical ‘ smog, tends to happen as a consequence of increased N oxides or hydrocarbon concentrations in the ambiance due to fumess from internal burning engines. Nitrogen oxides can be broken down by sunshine to organize groups doing low degree ozone formation, azotic acid, peroxides, aldehydes and ketones.

Both types of smog are more likely to organize in metropoliss and as a consequence of deficiency of air current. The deficiency of air motion can ensue in a temperature inversion which causes a bed of still warm air to cover a bed of cool air, pin downing any pollutants below the warm bed near land degree.

What is the difference between stratospheric and tropospheric ozone? Explain the function of NOx in the coevals of tropospheric ozone.

The ozone bed typically occurs in the stratosphere and is of course formed and decomposed from the reactions between O and O free groups which are formed from the decomposition of O by ultraviolet visible radiation. The stratosphere is typically located from around 20 to 50 kilometers above the Earth ‘s surface. The happening of ozone at this degree helps absorb harmful UV visible radiation.

Tropospheric ozone refers to ozone happening in the troposphere ( up to 12 kilometers above the Earth ‘s surface ) . Ozone at this degree can be toxicant and besides acts as a nursery gas with a heat pin downing effectivity of 2000 times greater than CO2.

The dislocation of N dioxide by ultraviolet visible radiation can take to the formation of O free groups.

NO2 = NO + O*

O* + O2 = O3

Describe the mechanisms for acerb rain and eutrophication, severally. What are the effects of these two environmental impacts?

Acid rain is chiefly formed from SOx and NOx. Sulphur oxides are oxidised in the presence of ultraviolet visible radiation to organize sulphur trioxide gas, through responding with H2O, this can so organize acid rain in the signifier of sulfurous acid and/or sulfuric acid. Nitrogen oxides are oxidised to nitrogen dioxide which may so take to the reaction between H2O and N dioxide leting for the formation of azotic and azotic acid. Acid rain can consequence flora, lakes and rivers, edifices and human wellness.

Eutrophication is the procedure that occurs due to inordinate growing of home grounds to an extent where the growing becomes destructive to the environment. Use of unreal fertilizers from farming leads to increased degrees of nitrates and phosphates roll uping in lakes and rivers. The nitrates and phosphates are foods that increase the growing of workss and algae. When these workss and algae die they can break up aerobically to organize C dioxide and H2O. With inordinate decomposition, O will be depleted and anaerobiotic decomposition will happen, taking to formation of hydrides such as ammonium hydroxide and H sulfide. More species will decease due to poisoning caused by the hydrides and may finally take to the decease of the full home ground.

Which of the above environmental impacts do nitrogen oxides contribute to? Explain how.

Nitrogen oxides contribute to the formation of acid rain either in the signifier of azotic or azotic acid.

Upon absorbing ultraviolet light N dioxide breaks down to organize nitrogen oxide and O groups. These groups can unite with H2O to organize hydroxyl groups which may so respond with nitrogen oxide to organize azotic acid.

Air pollution bar and control

What options exist for the bar and clean-up of acid gas emanations?

Emissions of N oxides can potentially take to the formation of acid rain, with several options available for its bar and clean-up. These chiefly include selective catalytic decrease ( SCR ) , non-selective catalytic decrease ( NSCR ) , and selective non-catalytic decrease ( SNCR ) .

The power industry uses SCR for post-combustion NOx clean up and/or low NOx burners and SNCR for bar of NOx formation in the burning phase. SCR involves responding ammonium hydroxide or urea with NOx over V oxide accelerators in a temperature scope of 300 to 400 A°C and can take up to 95 % of NOx. SNCR involves shooting ammonia/urea in the furnace at temperatures of 900 to 1100 A°C, with a removal efficiency of merely around 30 % .

Non-selective catalytic decrease removes NOx in a method analgous to the tripartite catalytic convertor used in the automotive industry. This is typically applied in the chemical industries.

Sulphur oxides can besides take to acid rain. Flue gas desulphurisation ( FGD ) works involves scouring the gasses to take sulfur oxides. For illustration, limestone scouring is one method of FGD, which converts sulfur oxides into Ca sulfate dihydrate ( gypsum ) .

Which stages in the life rhythm of an installing must be considered within the IPPC Directive?

All phases of the life rhythm should be considered ; i.e. from cradle to sculpt. In order to supply an incorporate attack, no phase can be left out, and a full appraisal of the environmental, societal and economic impacts should be carried out for the natural stuffs, processing, storage and transit phases involved.

Which industrial sectors are regulated by the IPPC Directive? Why do you believe these sectors have been included under the IPPC Directive?

The industries covered by the IPPC directing include:

Energy Production


Production & A ; Processing of Metallic elements

Production of Cement & A ; Lime

Activities affecting Asbestos

Glass, Glass Fibre and other Mineral Fibre Manufacture

Ceramic Production

Organic & A ; Inorganic Chemical Production

Fertiliser & A ; Biocide Manufacture

Pharmaceutical Industry

Explosives Industry

Storage of Bulk Chemicals



Paper Industry

Tar & A ; Bitumen Processes

Coating, Printing and Textile Activities

Dye, Ink and Coating Material Industry

Timber Activities

Rubber Activities

Processing of Food ; and

Intensive Farming.

These sectors have been included under the Directive due to the demand of commanding and restricting the environmental impact these industries can hold during the fabricating procedure of their relevant merchandises.

Case survey: Identifying BAT for the bar and control of NOx emanations

Nitric acid industry

What influences the output of azotic acid? Why is it of import to maximize its output?

The output of azotic acid is effected by:

The efficiency of the catalytic oxidization of ammonium hydroxide to nitrogen monoxide

The efficiency of the oxidization of N monoxide to nitrogen dioxide

The soaking up of N dioxide in H2O to bring forth azotic acid

Maximizing its output allows for an efficient production ; therefore bring forthing more azotic acid at the same operating costs to accomplish larger net incomes. Maximizing output means understating unreacted N oxide which is accordingly released to atmosphere.

Why are the reaction ( 6 ) and the contrary of reaction ( 4 ) unwanted in this procedure?

The contrary of reaction 4 consequences in a lower NO2 output as the reaction will be given towards the NO and O2 through a displacement in equilibrium to the reactants. As the soaking up of NO2 is limited by NO2 concentration, it is desirable to guarantee the forward reaction in reaction 4 occurs in order to maximize HNO3 output. In add-on to this, the happening of a rearward reaction ( 4 ) in which NO is formed allows for the possibility of azotic acid formation ( reaction 6 ) . Again this is unwanted as NO2 is consumed in bring forthing an unwanted merchandise, accordingly taking to a lower NO2 concentration and lower HNO3 outputs.

In add-on to NOx and N2O emanations, what other releases to air, H2O and land can be expected from azotic acid industry? What environmental impacts can these releases cause?

Carbon dioxide emanations from firing fossil fuels for energy demands and transit should be accounted for, every bit good as ammonium hydroxide, azotic acid, azotic acid escapes.

Pollution bar and control of NOx emanations

Pollution bar: Procedure design and operation

The efficiency of NO2 soaking up to bring forth HNO3 can be increased farther by increasing force per unit area. Discourse the advantages and disadvantages of pressurised systems in footings of their proficient complexness, environmental impacts ( including noise ) and economic costs.

As stated, the chief advantage of a pressurised system is the improved soaking up of NO2 to bring forth HNO3, this consequences in less NO2 being released to the ambiance. However, pressurised systems require a more complex design as a consequence of the serious safety considerations associated with them. Failure of pressurised systems can take to decease or hurt of workers on-site every bit good as the release of NO2 to atmosphere.

Pressurised systems would necessitate increased compaction and pumping responsibilities, lending to increased noise pollution, runing costs and care costs. The soaking up column may non hold been designed for higher force per unit areas, i.e. stuffs of building, column thickness, and column closings may non be suited, and therefore alterations would hold to be made, ensuing in increased capital costs. These costs must be compared with the improved azotic acerb output in order to to the full asses this option.

Discuss the advantages and disadvantages of providing pure O alternatively of air for oxidization of NO in the HNO3 soaking up tower. Address the undermentioned issues:

What are the advantages of utilizing pure O alternatively of air in footings of oxidization efficiency, gas flowrates, column volume etc?

Using pure O instead than air ( 21 % O, 79 % N ) , allows for the volumetric gas flowrate of this watercourse to be reduced by 79 % due to the riddance of N. This consequences in an improved oxidization efficiency, leting more NO2 to be formed by cut downing the sum of NO. The decreased gas flowrate consequences in a decreased column volume, presuming a changeless gas hourly infinite speed.

Unlike air, O does non come for free – it has to be produced by dividing N from air ( you may retrieve this from the last twelvemonth ‘s coursework on Waste Water Treatment within the faculty Introduction to Sustainable Development ) . This is normally done in a big graduated table cryogenic procedure ( separation by chilling ) . What are the deductions of this in the context of IPPC ( i.e. taking into history all life rhythm phases associated with this procedure option ) ?

The cryogenic separation of O from air is a extremely energy intensive procedure. The chief phases of the procedure include compaction, chilling, and distillment. From a life-cycle position, the natural stuff ( air ) is free ; nevertheless, it is the processing phase which incurs the bulk of environmental impact. Energy is required in the compaction and distillment phases of the procedure, therefore, presuming energy is obtained from fossil fuel beginnings, nursery gas emanations become a concern. Further to this, the demand of infrigidation may hold environmental impacts depending on the refrigerant used. Transportation system of the O to the azotic acid works may hold possible impacts ; nevertheless, in comparing to the processing phase, any environmental impacts are likely to be comparatively little. Therefore the production of O does hold an environmental impact to an extent ; nevertheless, the IPPC does non use to this industry, so due to the deficiency of IPPC ordinance in the sector inefficiencies or environmental concerns may indirectly consequence the azotic acid fabrication procedure. The cardinal concern of utilizing pure O is the extra cost.

Pollution bar: Extended soaking up

Explain the thought behind drawn-out soaking up. What is the nexus between the figure of transportation units ( NTU ) in the HNO3 soaking up tower and the NOx emanations?

Extended soaking up ( EA ) allows for any unreacted N dioxide to be absorbed in a 2nd tower, therefore increasing azotic acid production and cut downing NOx emanations. Oxygen can besides be injected to oxidize any nitrogen monoxide so that it can be absorbed in the new soaking up column. An addition in NTU in the HNO3 soaking up tower consequences in lower NOx emanations.

How would you cipher the needed tallness of the soaking up column to increase the HNO3 production output and cut down the emanations of NOx from the industry of azotic acid? What information and information would you necessitate to make that? ( See the Appendix. )

In order to cipher the needed tallness of the soaking up column, the NTU must be calculated. This requires the gas mole fraction at the top of the column ( yT ) and at the underside ( ytterbium ) . The gradient of the operating line, R is besides required, this is obtained from the equilibrium of the operating line, the grinder gas flowrate, and the molar liquid flowrate per unit tower country.

This value is so multiplied by the tallness of a transportation unit which is given by:

Where G is the molar gas flowrate per unit tower country, Bluegrass State is the overall mass transportation coefficient, and a is the interfacial country per unit jammed volume.

Height = HTU x NTU

Pollution control: Absorption in Na hydrated oxide

IPPC requires consideration of wider impacts of an activity, which means consideration of a figure of life rhythm phases of a procedure. In the instance of NOx scouring by Na hydrated oxide, what parts of the life rhythm must be included for BAT appraisal? Analyzing this system, explicate why soaking up of NOx in NaOH is improbable to stand for BAT.

All phases of the life rhythm must be considered for a through and thorough analysis of BAT appraisal. The concluding phase of the life-cycle for the Na hydrated oxide scouring option is a cardinal concern. The disposal of the Na nitrite-nitrate wastewater is a cardinal concern. If no suited disposal or recycle method can be identified for the wastewater, so along with the increased costs incurred from NaOH feedstock and increased pumping, this option does non stand for BAT.

Pollution control: Non-selective catalytic decrease ( NSCR )

Non-selective catalytic decrease ( NSCR ) is quite efficient in cut downing the emanations of NOx from the industry of azotic acid. However, it besides generates extra environmental impacts. Identify these impacts for H and natural gas as cut downing agents, severally, and explicate the beginning of these impacts.

The demand of a cut downing agent such as H and natural gas has important environmental deductions. Hydrogen is likely to hold been produced from steam reforming of fossil fuels, and natural gas is a fossil fuel, hence, consideration should be given to the procedure of pull outing the dodo fuel, transporting it and treating it. In the instance of H, the processing phase is likely to be a cardinal concern as it is an energy intensive procedure which consequences in farther emanations and extra environmental impacts. For illustration, steam reforming of methane to bring forth H and C monoxide is an endothermal reaction necessitating heat generated frequently from firing fossil fuels. However, utilizing methane as a cut downing agent leads to the formation of CO2 in the procedure.

Calculate the sum of C dioxide in t/yr generated in the NSCR procedure which removes 1.5 T NO2/day from the azotic acid tail gas utilizing natural gas. Calculate the potency for planetary heating from these CO2 emanations. Compare that with the planetary heating avoided by the remotion of the tantamount sum of N2O per twenty-four hours from the same tail gas. What do you reason?

2CH4 + O2 + 2NO2 +2N2O = 2CO2 + 4H2O + 3N2

Mass of NO2 = 1500 kg/day

Molecular Weight of NO2 = 46.01 kg/mol

Gram molecules of NO2 = 32.60 kmol/day

Gram molecules of CO2 = ( 2/2 ) * Moles of NO2 = 32.60 kmol/day

Molecular Weight of CO2 = 44.01 kg/kmol

Mass of CO2 = 1.4 T CO2/day

Assuming that the works is operational for 365 yearss per twelvemonth, the one-year sum of C dioxide generated by the NSCR procedure can be estimated as 524 metric tons per twelvemonth.

N2O has a heat pin downing effectivity of 150 times that of CO2 ; therefore the salvaging made by change overing N2O to CO2 is significant with respects to planetary warming possible. The N2O produced would be tantamount to 78,551 metric tons of CO2 per twelvemonth.

Use the illustration in the old inquiry to cipher the tantamount acidification impact that would be avoided by the remotion of NOx with the NSCR procedure. Compare this avoided impact with planetary heating generated through the usage of natural gas to take the NOx. What do you reason? How should we near state of affairss like these, where cut downing one environmental impact causes another?

The categorization factor for NOx is estimated as 0.7 kg/kg. Therefore acidification nest eggs can be estimated as 1050 kg/day which is tantamount to 383 metric tons per twelvemonth. In comparing to the 524 metric tons of CO2 produced per twelvemonth, it can be noted that the decrease of the acidification impact does non outweigh the CO2 produced in the procedure.

Pollution control: Selective catalytic decrease ( SCR )

What are the chief environmental and safety concerns associated with the selective catalytic decrease ( SCR ) procedure?

SCR typically uses ammonium hydroxide or urea to catalytically change over N oxides to molecular N and H2O ; nevertheless, the production of these reactants have cardinal environmental considerations. Ammonia production typically involves steam reforming of a hydrocarbon feedstock such as natural gas or naphtha. Therefore, fossil fuel depletion and the issues environing dodo fuel extraction, transit and processing are all cardinal sustainability concerns. However, ammonia produced from naphtha would be more of a concern than ammonium hydroxide produced from natural gas due to the extra refinement procedure from which it is produced. Ammonia production besides involves the emanation of C dioxide, a nursery gas.

Gas preheating besides has an impact on energy demands and therefore nursery gas emanations.

On-site ammonium hydroxide or urea storage would be required ; any escapes of ammonium hydroxide could turn out fatal as it is toxic upon inspiration.

Catalyst disposal may besides hold assorted environmental impacts depending on the toxicity of the used accelerator.

Why is it of import to understate ammonium hydroxide “ faux pas ” from the SCR procedure for NOx control?

The happening of ammonium hydroxide faux pas consequences in inefficient usage of feedstock. Costss can be notably reduced by guaranting minimal ammonium hydroxide faux pas throughout operation. Ammonia may besides respond with other compounds to organize unwanted merchandises. For illustration, ammonium bisulphate formation in power industry frequently consequences in harm to air warmers. Therefore, this should be farther investigated for the application of azotic acid production to guarantee any unwanted compounds are non formed. Further to this, as ammonium hydroxide is toxic, any ammonia faux pas would ensue in release to atmosphere ; hence possible wellness concerns exist.

Balancing environmental and economic costs

What would be your reply to the above inquiry on the comparing between SCR and NSCR?

From table 2, it is apparent that SCR can supply an improved NOx remotion ( exit degree of 100 ppm ) in comparing to NSCR ( 205 PPM ) ; nevertheless, SCR ‘s failure to take N2O may be a cardinal concern when compared to NSCR which does take the compound. However, unlike NSCR, SCR does non ensue in important CO2 emanations. The economic sciences of both options demonstrate that when combined with EA, NSCR is significantly more expensive than SCR and merely provides an betterment of 0.3 % . Therefore SCR would be chosen over NSCR.

Analyse the informations shown in Tables 3 and 4 and do your ain pick of BAT for NOx bar and control. Explain and warrant your pick.

The important costs of NSCR in comparing to SCR would ensue in increased azotic acid monetary values, to the extent where it would non be profitable to fabricate. The little additions in remotion efficiency made utilizing NSCR over SCR with EA do non warrant the big difference in monetary value ; hence, the pick of BAT is between EA and EA with SCR. With EA adding a cost ? 230 per metric ton of acid, and EA+SCR adding a cost of ? 880 per metric ton of acid, from an economic position it would be most suited to take EA due to its high NOx remotion of 94.8 % . However, the improved removal efficiency of SCR ( 98.5 % ) does let for an statement to be made for its pick as BAT. With respects to be, EA+SCR does supply increased costs and lower net incomes ; nevertheless, its ability to sufficiently run into IPPC marks can non be overlooked, therefore for this ground, it should be chosen as BAT.

The societal deductions of the pollution bar and control techniques have non been considered above. Can you place them for each option? Do the societal considerations change your pick of BAT?

Both EA and EA+SCR portion common societal deductions such as the building of new works soaking up column for EA, and a reactor for SCR. This involves building vehicles going through the country, ensuing in increased noise pollution. Other societal impacts of EA are minimum as an increased compaction demand may ensue in somewhat increased noise pollution. If energy is generated on-site for the compressors, so higher nursery gas emanations may be a concern. With respects to SCR, ammonium hydroxide faux pas is a cardinal concern, as the gas is toxic when inhaled. Further to this, the energy required for gas pre-heating besides contributes to increased nursery gas emanations. Overall the EA option proves more suited in footings of cut downing societal impacts and so this would be the option for BAT.

Choosing BAT

Why do you believe the company has chosen to see these two options and non any other described above?

Choosing to modify the soaking up column in order to run at higher force per unit areas would be a batch cheaper than using the extend soaking up option which would necessitate the building of an extra column, therefore ensuing in increased capital and operational costs. In add-on to this, this option would be chosen over the NaOH soaking up procedure, once more due to the increased capital costs ensuing from an extra soaking up tower and the increased operational costs incurred from a NaOH provender. Increasing operating force per unit area does non hold any important on-site environmental releases/impacts other than an increased compaction responsibility. SCR may hold been chosen due to its easiness to be retrofitted and its high remotion efficiency. In comparing to other options, SCR provides the best public presentation for NOx remotion.

Choosing Bat: Environmental considerations

See the LCA consequences shown in Figure 5 and reply the undermentioned inquiries:

Why do you believe the SCR option has higher dodo fuel and ozone depletion than the base instance?

The demand of natural gas for the production of ammonium hydroxide is likely to be the primary cause of increased dodo fuel depletion for SCR. NOx formed during ammonia production may besides be a cause of the increased ozone depletion associated with SCR. In add-on to this, ammonia faux pas may ensue in ammonium hydroxide being released to atmosphere which so reacts with ammonium hydroxide to bring forth ammonium nitrate.

The fact that SCR is better for some impacts but worse for the others when compared with the base instance makes it more hard to take BAT. If you as a works operator had to take between these two options, which one would you take? Justify your pick by discoursing the ‘significance ‘ of planetary impacts ( such as ozone depletion and dodo fuel depletion ) and regional and local impacts ( such as acidification and photochemical smog ) .

In comparing to the base instance, SCR merely has a somewhat higher dodo fuel and ozone depletion ; whereas other impacts such as acidification and human toxicity are significantly reduced through utilizing SCR. As efficiencies are made in the ammonium hydroxide production procedure, SCR could potentially hold a reduced impact on dodo fuel depletion. In add-on to this, the production of ammonium hydroxide utilizing energy from renewable beginnings is besides an option to cut down fossil fuel depletion, every bit good as the ability to bring forth H from the electrolysis of H2O utilizing renewable energy.

Based strictly on environmental considerations, which process out of the three options ( base instance, HP and SCR ) would you take as BAT? Explain why.

Based merely on the environmental considerations, HP demonstrates BAT. In comparing to the base instance and SCR, HP has the least environmental impact for fossil fuel depletion, planetary heating, ozone depletion, acidification, photochemical smog, and human toxicity.

Compare now the SCR and HP options in footings of the degree of NOx emanations that they can accomplish. Which procedure would you as an operator choose? Why?

The HP alteration has a removal efficiency of 84 % , taking 1202 ppm of NOx ; nevertheless, SCR has a greater removal efficiency of 93 % , taking 1332 ppm of NOx. As the base instance works produces 1432 ppm of NOx per hr, the mercantile establishment concentrations for the HP and SCR alterations are 230 ppm and 100 ppm, severally. SCR ‘s effectivity in taking NOx is notably greater than that of the HP option ; hence, from an operational point of position, SCR would be chosen.

Combine both the environmental impacts and the degrees of NOx emanation that each option can accomplish and do an overall pick of BAT. Justify your pick by taking into history the IPPC rules.

Both options satisfy the IPPC rules to a certain extent. However, HP has greater conformity than SCR with the IPPC rules. HP and SCR both provide protection for the environment as a whole by cut downing NOx emanations from the azotic acid works. Although, SCR has improved removal efficiency over HP, the impact of ammonium hydroxide production fails to show SCR as the BAT in comparing to HP in this instance. HP provides a better instance for pollution bar, by cut downing NOx formation throughout the procedure ; whereas SCR demonstrates a instance for pollution control. As bar is preferred to command, HP once more provides the better option. In supplying a balance between the environment, economic sciences and societal impacts, HP provides the better option. Significant decreases in planetary warming possible, acidification and human toxicity are made through using HP over SCR, with noteworthy additions in cut downing fossil fuel depletion, ozone depletion and photochemical smog. Although SCR demonstrates an improved NOx remotion efficiency, overall, the environmental impact as a whole can be reduced by using HP alterations. Further to this, the income generated by HP alterations, can lend to farther works alterations taking to improved procedure efficiencies. Therefore, sing its wider conformity with IPPC rules HP would be chosen as BAT.

Choosing BAT: Socio-economic considerations

Choose your preferable NOx bar or control option sing the internal ( MAC ) and external costs ( MDC ) shown Tables 6 and 7. Justify your pick.

With respects to the fringy suspension costs ( MAC ) for NOx emanations, the HP option clearly proves to be the more attractive option due to the nest eggs made ( MAC = ? -92 per ppm ) . The excess energy generated and increase in acid produced leads to improved gross which accordingly reduces the operating cost of the works. However, SCR increases runing cost by ? 225 per ppm of NOx removed. In order to asses if SCR ‘s improved remotion efficiency can warrant such a cost, the fringy harm cost of both options was compared. The consequences indicate that MDC due to NOx emanations was lower for SCR ( ? 35,770 per twelvemonth ) than for HP ( ? 82,320 per twelvemonth ) . However, the MDC fails to see environmental impacts other than NOx emanations. If costs were considered for the impacts of ammonium hydroxide production, it is likely that the MDC for SCR would be much higher. Sing this, HP was chosen as the best option.

Choosing BAT: The whole image

List all standards relevant for taking BAT in the above instance survey. On the footing of the consequences obtained, rank the three options in order of their desirableness. You may wish to make a superior tabular array, delegating a figure to each engineering to bespeak the order of penchant on a graduated table from 1-3 ( e.g. figure 1 indicates the best option and 3 the worst ) ; this ranking should be done for each standard you have listed.

NOx removal efficiency/Marginal Damage Costss



Base Case

Fringy Suspension Costss


Base Case


Life-Cycle Environmental Impacts



Base Case

Conformity with IPPC Principles



Base Case

Identify BAT for the conditions of this instance survey, presuming that you are Head of Engineering and Technology Division in a company. Justify your pick.

Based on the standards listed in inquiry 1, HP demonstrates the most suited option for IPPC conformity, cut downing overall environmental impacts every bit good as supplying nest eggs in operating costs. Although SCR has a greater NOx remotion efficiency, HP is systematically and in some instances significantly better than SCR in cut downing environmental impacts such as fossil fuel depletion, planetary heating, ozone depletion, acidification, photochemical smog, and human toxicity. In add-on to this, taking HP non merely reduces the works ‘s environmental impact, but allows for improved energy coevals onsite. Therefore, additions in efficiency can be made, cut downing trust on volatile energy monetary values. The HP option does non necessitate extra feedstock, unlike SCR ‘s ammonium hydroxide demand, and is hence non as straight exposed to monetary value fluctuations. Therefore, the option of HP alteration is economically and environmentally justified, ensuing in a cleaner and more efficient azotic acid production works.

Now assume that you are:

a local occupant ;

an environmental militant ;

an Environment Agency inspector ; and

Government curate for the environment and societal personal businesss.

and take BAT. Justify your pick by discoursing what considerations would be of import for you in each of the functions in taking the BAT and explicate why.

As a local occupant I would be concerned with local environmental impacts. However, sing that the bulk of occupants may be merely concerned with seeable impacts SCR may be chosen as the best option. As SCR would let for greater NOX remotion ; the orange plume of NOx emanations would non be every bit noticeable as it might be with merely HP. Therefore, the absence of a colored plume would propose to the mean occupant that the works is non as polluting.

An environmental militant is more likely to be cognizant of the wider environmental impacts associated with utilizing HP or SCR. Therefore, as HP alterations allow for greater decreases over a scope of environmental impacts, it is likely that this option would be chosen alternatively of SCR.

An Environment Agency inspector would be more concerned with the conformity of NOx emanation bounds and due to the SCR ‘s greater remotion efficiency, this is likely to be chosen.

A authorities curate is likely to be cognizant of a greater scope of issues, including costs, NOx emanation bounds, and all environmental impacts. However, it is likely that the IPPC would be a cardinal concern ; therefore, HP ‘s wider conformity with the IPPC rules may ensue in the HP alteration option to be chosen.

What can you reason in footings of how different considerations influence different stakeholders ( i.e. companies, local occupants, the regulator and the authorities ) in taking BAT?

From the assorted considerations it can be noted that different groups of stakeholders have different precedences in footings of taking BAT ; hence, any concluding pick should be a via media and supply a suited balance between economic, societal and environmental costs.