Reduced pollution

Although the first impulse for emission reduction is often to add a control device, this may not be the environmentally best or least cosdy approach. Process examination may reveal changes or alternatives that can eliminate or reduce pollutants, decrease the gas quantity to be treated, or render pollutants mote amenable to collection. Following are principles to consider for controlling pollutants without the addition of specific treatment devices, ie, the fundamental means of reducing or eliminating pollutant emissions to the atmosphere (30) ... 

When chlorine dioxide is used for pulp bleaching in conjunction with the Kraft (sulfide) process for chemical pulping, by-product sodium sulfate can be used as a source of makeup sulfur and sodium consumed in the chemical cycle. The demand for sodium and sulfur in pulp bleaching is related to the loss of these chemicals through carryover in unbleached pulp. As process improvements have sought to reduce pollution from pulp mills, less sodium sulfate makeup is required. The trends in pulp bleaching to increase substitution of chlorine with chlorine dioxide have caused an oversupply of sodium sulfate, so that this by-product is often regarded as waste (81). 

L. R. Embei, Strategies for Reducing Pollution at the Source are Gaining Ground, C E News, July 8, 1991, p. 7. 

As air pollution management moves forward, economics has a major role in reducing pollution. Multimedia considerations are forcing a blend of traditional emission reduction approaches and innovative methods for waste minimization. These efforts are directed toward full cost accounting of the life cycle of products and residuals from the manufacturing, use, and ultimate disposal of materials. 

Although numerous cases have been documented where petroleum refineries have simultaneously reduced pollution outputs and operating costs through pollution prevention techniques, there are often barriers to their im-plementation. The primary barrier to most pollution prevention projects is cost. Many pollution prevention options simply do not pay for themselves, or the economics often appear marginal. Corporate investments typically must earn an adequate return on invested capital for the shareholders and some pollution prevention options at some facilities may not meet the requirements set by company policies. 

Pollution prevention is always preferred to the use of end-of-pipe pollution control facilities. Therefore, every attempt should be made to incorporate cleaner production processes and facilities to limit, at source, the quantity of pollutants generated. The choice of flash smelting over older technologies is the most significant means of reducing pollution at source. Sulfur dioxide emissions can be controlled by ... 

Does your company take corrective actions aimed at reducing pollution, or does it monitor and react to environmental problems Which do you think is a better approach to managing environmental issues and why ... 

Desulfurization removal of sulfur from fossil fuels to reduce pollution. 

To reduce pollution contamination, sensors or receptors installed m ducts or pipes are placed and installed after the filtration of the air or fluid. Sensors in pipes must be installed primarily in bends and in the direction against dynamic flow. At least two-thirds of the sensor pocket has to be in contact with the fluid. If the pipe diameter is less than the sensor length, the pocket can be installed at an angle less than 90° against the direction of flow to provide the necessary contact area. 

Product recovery The recovery of the waste products from a process reducing pollution, saving energy or materials. 

At other times the burning of waste products in furnaces to save fuel and reduce pollution has caused corrosion and tube failure. 

Tecluiical assistance programs tliat provide on-site help to companies and organiziitions in reducing pollution at tlie source... 

One feature of the new law is an SO, trading allowance program that encourages the use of market-based principles to reduce pollution. Utilities may trade allowances within their system and/or buy or sell allowances to and from other affected sources. For example, plants that emit SO, at a rate below 1.2 Ib/million Btu will be able to increase emissions by 20 percent between a baseline year and the year 2000. Also, bonus allowances will be distributed to accommodate growth by units in states with a statewide average below 0.8 Ib/million Btu. 

To reduce pollution, Dow developed a new catalyst system from the mor-denite-zeolite group to replace phosophoric acid or aluminum chloride catalysts. The new catalysts eliminates the disposal of acid wastes and handling corrosive materials. 

Boilers may be direct fired or indirect fired. Energy supply designs account for various combustion methods using fossil fuels, municipal waste, process residues, waste heat, and by-products. Special boiler combustion systems to reduce pollution or improve efficiency include fluidized-bed and combined cycle. 

Ionic liquids are compounds in which one of the ions is a large, organic ion that prevents the liquid from crystallizing at ordinary temperatures. The low vapor pressures of ionic liquids make them desirable solvents that reduce pollution. 

Ethanol, CH3CH2OH, is produced from the biological fermentation of the starches in grains, mainly corn. It currently makes up about 10% by volume of gasoline in the United States, thereby reducing pollution as well as the use of petroleum. The oxygen atom in the ethanol molecule reduces emissions of carbon monoxide and hydrocarbons by helping to ensure complete combustion. One bushel of... 

The Industrial Revolution was made possible by iron in the form of steel, an alloy used for construction and transportation. Other d-block metals, both as the elements and in compounds, are transforming our present. Copper, for instance, is an essential component of some superconductors. Vanadium and platinum are used in the development of catalysts to reduce pollution and in the continuing effort to make hydrogen the fuel of our future. 

National initiatives in North America and Europe are designed to reduce pollution emissions from both stationary and mobile sources. Independently of whether they succeed in reducing pollutant loadings, the available evidence indicates that alterations in affected forests will continue. Obviously, no one knows what affected forests will be like in 50 years. There is little doubt that they will be different. And the sooner the anthropogenic causal factors - all of them - are reduced qualitatively and quantitatively, the better are the chances of retaining or regenerating forests that will have meaning and value for those who will want to use them. 

Generally, the above transesterification reactions are catalyzed by strong acids or alkalis [1, 2]. In the homogeneous catalytic process by acids or alkalis, neutralization is required of the product. This post-treatment produces waste water, and increases equipment investment and production cost. Recently, more attention has been paid to the heterogeneous catalysis process [3] for an easier production process and to reduce pollution of the environment. 

Catalytic converters convert much of the NO and NO2 from exhaust gases into N2 and O2 before they are released into the atmosphere. These have helped alleviate pollution from nitrogen oxides at only a small additional cost. We could reduce pollution emissions even ftirther, but consumers and manufacturers are reluctant to pay the higher costs required to develop and produce cleaner ftiels and engines. 

The benefits of TES include [2] (i) reduced energy costs, (ii) reduced energy consumption, (iii) improved indoor air quality, (iv) increased flexibility of operation, (v) reduced initial and maintenance costs, (vi) reduced equipment size, (vii) more efficient and effective utilization of equipment, (viii) conservation of fossil fuels, and (viii) reduced pollutant emissions. 

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