18.1 SECTION 18 ENVIRONMENT AL CONTROL AND ENERGY CONSERV ATION ENVIRONMENTAL CONTAMINATION ANALYSIS AND PREVENTION 18.2 Recycle Profit Potentials in Municipal Wastes 18.2 Choice of Cleanup Technology for Contaminated Waste Sites 18.4 Cleaning Up a Contaminated Waste Site Via Bioremediation 18.10 Process and Effluent Treatment Plant Cost Estimates by Scale-Up Methods 18.16 Determination of Ground-Level Pollutant Concentration 18.20 Estimating Hazardous-Gas Release Concentrations Inside and Outside Buildings 18.21 Determining Carbon Dioxide Buildup in Occupied Spaces 18.23 Environmental Evaluation of Industrial Cooling Systems 18.24 STRATEGIES TO CONSERVE ENERGY AND REDUCE ENVIRONMENTAL POLLUTION 18.29 Generalized Cost-Benefit Analysis 18.29 Selection of Most Desirable Project Using Cost-Benefit Analysis 18.30 Economics of Energy-From-Waste Alternatives 18.32 Flue-Gas Heat Recovery and Emissions Reduction 18.36 Estimating Total Costs of Cogeneration-System Alternatives 18.42 Choosing Steam Compressor for Cogeneration System 18.48 Using Plant Heat Need Plots for Cogeneration Decisions 18.52 Geothermal and Biomass Power- Generation Analysis 18.58 Estimating Capital Cost of Cogeneration Heat-Recovery Boilers 18.62 ‘‘Clean’’ Energy from Small-Scale Hydro Site 18.67 Central Chilled-Water System Design to Meet Chlorofluorocarbon (CFC) Issues 18.70 Work Required to Clean Oil-Polluted Beaches 18.73 Sizing Explosion Vents for Industrial Structures 18.75 Industrial Building Ventilation for Environmental Safety 18.78 Estimating Power-Plant Thermal Pollution 18.82 Determining Heat Recovery Obtainable by Using Flash Steam 18.83 Energy Conservation and Cost Reduction Design for Flash Steam 18.87 Cost Separation of Steam and Electricity in a Cogeneration Power Plant Using the Energy Equivalence Method 18.92 Cogeneration Fuel Cost Allocation Based on an Established Electricity Cost 18.96 Fuel Savings Produced by Direct Digital Control of the Power- Generation Process 18.99 Small Hydro Power Considerations and Analysis 18.101 Ranking Equipment Criticality to Comply with Safety and Environmental Regulations 18.104 Fuel Savings Produced by Heat Recovery 18.109 Fuel Savings Using High-Temperature Hot-Water Heating 18.111 CONTROLS IN ENVIRONMENTAL AND ENERGY-CONSERVATION DESIGN 18.114 Selection of a Process Control System 18.114 Process-Temperature Control Analysis 18.117 Computer Selection for Industrial Process-Control Systems 18.118 Control-Valve Selection for Process Control 18.122 Controlled-Volume-Pump Selection for a Control System 18.124 Steam-Boiler-Control Selection and Application 18.125 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: HANDBOOK OF MECHANICAL ENGINEERING CALCULATIONS 18.2 ENVIRONMENTAL CONTROL TABLE 1 Examples of Price Changes in Municipal Wastes* Price per ton, $ Last year Current year Newspapers 60 150 Corrugated cardboard 18 150 Plastic jugs, bottles 125 600 Copper wire and pipe 9060 1200 *Based on typical city wastes. Control-Valve Characteristics and Rangeability 18.128 Fluid-Amplifier Selection and Application 18.129 Cavitation, Subcritical, and Critical- Flow Considerations in Controller Selection 18.130 Evaluating Repowering Options as Power-Plant Capacity-Addition Strategies 18.135 Cooling-Tower Choice for Given Humidity and Space Requirements 18.144 Choice of Wind-Energy Conversion System 18.151 Environmental Contamination Analysis and Prevention RECYCLE PROFIT POTENTIALS IN MUNICIPAL WASTES Analyze the profit potential in typical municipal wastes listed in Table 1. Use data on price increases of suitable municipal waste to compute the profit potential for a typical city, town, or state. Calculation Procedure: 1. Compute the percentage price increase for the waste shown Municipal waste may be classed in several categories: (1) newspapers, magazines, and other newsprint; (2) corrugated cardboard; (3) plastic jugs and bottles—clear or colored; (4) copper wire and pipe. Other wastes, such as steel pipe, discarded internal combustion engines, electric motors, refrigerators, air conditioners, etc., require specialized handling and are not generated in quantities as large as the four numbered categories. For this reason, they are not normally included in estimates of municipal wastes for a given locality. For the four categories of wastes listed above, the percentage price increases in one year for an Eastern city in the United States were as follows: Category Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. ENVIRONMENTAL CONTROL AND ENERGY CONSERVATION ENVIRONMENTAL CONTROL AND ENERGY CONSERVATION 18.3 1—newspaper: Percentage price increase ϭ 100(current price, $ Ϫ last year’s price, $)/last year’s price, $. Or 100(150 Ϫ 60)/60 ϭ 150 percent. Category 2: Percentage price increase ϭ 100(150 Ϫ 18)/18 ϭ 733 percent. Category 3: Percentage price increase ϭ 100(600 Ϫ 125) / 125 ϭ 380 percent. Category 4: Percentage price in- crease ϭ 100(1200 Ϫ 960)/960 ϭ 25 percent. 2. Determine the profit potential of the wastes considered Profit potential is a function of collection costs and landfill savings. When collection of several wastes can be combined to use a single truck or other transport means, the profit potential can be much higher than when more than one collection method must be used. Let’s assume that a city can collect Category 1, newspapers, and Category 3, plastic, in one vehicle. The profit potential, P, will be: P ϭ (sales price of the materials to be recycled, $ per ton Ϫ cost per ton to collect the materials for recycling, $). With a cost of $80 per ton for collection, the profit for collecting 75 tons of Category 1 wastes would be P ϭ 75($150 Ϫ $80) ϭ $5250. For col- lecting 90 tons of Category 3 wastes, the profit would be P ϭ 90($600 Ϫ 80) ϭ $46,800. Where landfill space is saved by recycling waste, the dollar saving can be added to the profit. Thus, assume that landfill space and handling costs are valued at $30 per ton. The profit on Category 1 waste would rise by 75($30) ϭ $2250, while the profit on Category 3 wastes would rise by 90($30) ϭ $2700. When collection is included in the price paid for municipal wastes, the savings can be larger because the city or town does not have to use its equipment or personnel to collect the wastes. Hence, if collection can be included in a waste recycling contract the profits to the municipality can be significant. However, even when the municipality per- forms the collection chore, the profit from selling waste for recycling can still be high. In some cities the price of used newspapers is so high that gangs steal the bundles of papers from sidewalks before they are collected by the city trucks. Related Calculations. Recyclers are working on ways to reuse almost all the ordinary waste generated by residents of urban areas. Thus, telephone books, mag- azines, color-printed advertisements, waxed milk jars, etc. are now being recycled and converted into useful products. The environmental impact of these activities is positive throughout. Thus, landfill space is saved because the recycled products do not enter landfill; instead they are remanufactured into other useful products. In- deed, in many cases, the energy required to reuse waste is less than the energy needed to produce another product for use in place of the waste. Some products are better recycled in other ways. Thus, the United States dis- cards, according to industry records, over 12 million computers a year. These com- puters, weighing an estimated 600 million pounds (272 million kg) contribute toxic waste to landfills. Better that these computers be contributed to schools, colleges, and universities where they can be put to use in student training. Such computers may be slower and less modern than today’s models, but their value in training programs has little to do with their speed or software. Instead, they will enable students to learn, at minimal cost to the school, the fundamentals of computer use in their personal and business lives. Recycling waste products has further benefits for municipalities. The U.S. Clean Air Act’s Title V consolidates all existing air pollution regulations into one massive operating permit program. Landfills that burn pollute the atmosphere. And most of the waste we’re considering in this procedure burns when deposited in a landfill. By recycling this waste the hazardous air pollutants they may have produced while burning in a landfill are eliminated from the atmosphere. This results in one less Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. ENVIRONMENTAL CONTROL AND ENERGY CONSERVATION 18.4 ENVIRONMENTAL CONTROL worry and problem for the municipality and its officials. In a recent year, the U.S. Environmental Protection Agency took 2247 enforcement actions and levied some $165-million in civil penalties and criminal fines against violators. Any recycling situation can be reduced to numbers because you basically have the cost of collection balanced against the revenue generated by sale of the waste. Beyond this are nonfinancial considerations related to landfill availability and ex- pected life-span. If waste has to be carted to another location for disposal, the cost of carting can be factored into the economic study of recycling. Municipalities using waste collection programs state that their streets and side- walks are cleaner. They attribute the increased cleanliness to the organization of people’s thinking by the waste collection program. While stiff fines may have to be imposed on noncomplying individuals, most cities report a high level of com- pliance from the first day of the program. The concept of the ‘‘green city’’ is catching on and people are willing to separate their trash and insert it in specific containers to comply with the law. ‘‘Green products, i.e., those that produce less pollution, are also strongly favored by the general population of the United States today. Manufacturing companies are finding a greater sales acceptance for their ‘‘green’’ products. Even automobile manufacturers are stating the percentage of each which is recyclable, appealing to the ‘‘green’’ thinking permeating the population. Recent studies show that every ton of paper not landfilled saves 3 yd 3 (2.3 m 3 ) of landfill space. Further, it takes 95 percent less energy to manufacture new prod- ucts from recycled materials. Both these findings are strong motivators for recycling of waste materials by all municipalities and industrial firms. Decorative holiday trees are being recycled by many communities. The trees are chipped into mulch which are given to residents and used by the community in parks, recreation areas, hiking trails, and landfill cover. Seaside communities some- times plant discarded holiday trees on beaches to protect sand dunes from being carried away by the sea. CHOICE OF CLEANUP TECHNOLOGY FOR CONTAMINATED WASTE SITES A contaminated waste site contains polluted water, solid wastes, dangerous metals, and organic contaminants. Evaluate the various treatment technologies available for such a site and the relative cost of each. Estimate the landfill volume required if the rate of solid-waste generation for the site is 1,500,000 lb (681,818 kg) per year. What land area will be required for this waste generation rate if the landfill is designed for the minimum recommended depth of fill? Determine the engineer’s role in site cleanup and in the economic studies needed for evaluation of available alternatives. Calculation Procedure: 1. Analyze the available treatment technologies for cleaning contaminated waste sites Table 2 lists 13 available treatment technologies for cleaning contaminated waste sites, along with the type of contamination for which each is applicable, and the Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. ENVIRONMENTAL CONTROL AND ENERGY CONSERVATION 18.5 TABLE 2 Various Treatment Technologies Available to Clean Up a Contaminated Waste Site* Technology Description Applicable contamination Relative cost Soil vapor extraction Air flow is induced through the soil by pulling a vacuum on holes drilled into the soil, and carries out volatilized contaminants Volatile and some semivolatile organics Low Soil washing or soil flushing Excavated soil is flushed with water or other solvent to leach out contaminants Organic wastes and certain (soluble) inorganic wastes Low Stabilization and solidification Waste is mixed with agents that physically immobilize or chemically precipitate constituents Applies primarily to metals; mixed results when used to treat organics Medium Thermal desorption Solid waste is heated to 200–800 ЊF to drive off volatile contaminants, which are separated from the waste and further treated Volatile and semivolatile organics; volatile metals such as elemental mercury Medium to high Incineration Waste is burned at very high temperatures to destroy organics Organic wastes; metals do not burn, but concentrate in ash High Thermal pyrolysis Heat volatilizes contaminants into an oxygen-starved air system at temperatures sufficient to pyrolzye the organic contaminants. Frequently, the heat is delivered by infrared radiation Organic wastes Medium to high Chemical precipitation Solubilized metals are separated from water by precipitating them as insoluble salts Metals Low Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. ENVIRONMENTAL CONTROL AND ENERGY CONSERVATION 18.6 TABLE 2 (Continued ) Technology Description Applicable contamination Relative cost Aeration or air stripping Contaminated water is pumped through a column where it is contacted with a countercurrent air flow, which strips out certain pollutants Mostly volatile organics Low Steam stripping Similar to air stripping except steam is used as the stripping fluid Mostly volatile organics Low Carbon adsorption Organic contaminants are removed from a water or air stream by passing the stream through a bed of activated carbon that absorbs the organics Most organics, though normally restricted to those with sufficient volatility to allow carbon regeneration Low to medium when regeneration is possible Bioremediation Bacterial degradation of organic compounds is enhanced Organic wastes Low Landfilling Covering solid wastes with soil in a facility designed to minimize leachate formation Solid, nonhazardous wastes Low but rising fast In situ vitrification Electric current is passed through soil or waste, which increases the temperature and melts the waste or soil. The mass fuses upon cooling Inorganic wastes, possibly organic wastes; not applicable to very large volumes Medium *Chemical Engineering. Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. ENVIRONMENTAL CONTROL AND ENERGY CONSERVATION ENVIRONMENTAL CONTROL AND ENERGY CONSERVATION 18.7 relative cost of the technology. This tabulation gives a bird’s eye view of technol- ogies the engineer can consider for any waste site cleanup. When approaching any cleanup task, the first step is to make a health-risk as- sessment to determine if any organisms are exposed to compounds on, or migrating from, a site. If there is such an exposure, determine whether the organisms could suffer any adverse health effects. The results of a health-risk assessment can be used to determine whether there is sufficient risk at a site to require remediation. This same assessment of risks to human health and the environment can also be used to determine a target for the remediation effort that reduces health and envi- ronmental risks to acceptable levels. It is often possible to negotiate with regulatory agencies a remediation level for a site based on the risk of exposure to both a maximum concentration of materials and a weighted average. The data in Table 2 are useful for starting a site cleanup having the overall goals of protecting human health and the environment. 2. Make a health-risk assessment of the site to determine cleanup goals 1 Divide the health-risk assessment into these four steps: (1) Hazard Identifica- tion—Asks ‘‘Does the facility or site pose sufficient risk to require further inves- tigation?’’ If the answer is Yes, then: (a) Select compounds to include in the as- sessment; (b) Identify exposed populations; (c) Identify exposure pathways. (2) Exposure Assessment—Asks ‘‘To how much of a compound are people and the environment exposed?’’ For exposure to occur, four events must happen: (a) release; (b) contact; (c) transport; (d ) absorption. Taken together, these four events form an exposure pathway. There are many possible exposure pathways for a fa- cility or site. (3) Toxicity Assessment—Asks ‘‘What adverse health effects in humans are po- tentially caused by the compounds in question?’’ This assessment reviews the threshold and nonthreshold effects potentially caused by the compounds at the en- vironmental concentration levels. (4) Risk Characterization—Asks ‘‘At the exposures estimated in the Exposure Assessment, is there potential for adverse health effects to occur; if so, what kind and to what extent?’’ The Risk Characterization develops a hazard index for thresh- old effects and estimates the excess lifetime cancer-risk for carcinogens. 3. Select suitable treatment methods and estimate the relative costs The site contains polluted water, solid wastes, dangerous metals, and organic con- taminants. Of these four components, the polluted water is the simplest to treat. Hence, we will look at the other contaminants to see how they might best be treated. As Table 2 shows, thermal desorption treats volatile and semivolatile organics and volatile metals; cost is medium to high. Alternatively, incineration handles organic wastes and metals with an ash residue; cost is high. Nonhazardous solid wastes can be landfilled at low cost. But the future cost may be much higher because landfill costs are rising as available land becomes scarcer. Polluted water can be treated with chemicals, aeration, or air stripping—all at low cost. None of these methods can be combined with the earlier tentative choices. Hence, the polluted water will have to be treated separately. 1 Hopper, David R., ‘‘Cleaning Up Contaminated Waste Sites,’’ Chemical Engineering, Aug., 1989. Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. ENVIRONMENTAL CONTROL AND ENERGY CONSERVATION 18.8 ENVIRONMENTAL CONTROL 4. Determine the landfill dimensions and other parameters Annual landfill space requirements can be determined from V A ϭ W/1100, where V A ϭ landfill volume required, per year, yd 3 (m 3 ); W ϭ annual weight, lb (kg) of waste generated for the landfill; 1100 lb/yd 3 (650 kg/m 3 ) ϭ solid waste compaction per yd 3 or m 3 . Substituting for this site, V A ϭ 1,500,000/1100 ϭ 1363.6 yd 3 (1043.2 m 3 ). The minimum recommended depth for landfills is 20 ft (6 m); minimum rec- ommended life is 10 years. If this landfill were designed for the minimum depth of 20 ft (6 m), it would have an annual required area of 1363.6 ϫ 27 ft 3 /yd 3 ϭ 36,817.2 ft 3 /20 ft high ϭ 1840.8 ft 2 (171.0 m 2 ), or 1840.9 ft 2 /43,560 ft 2 /acre ϭ 0.042 acre (169.9 m 2 ; 0.017 ha) per year. With a 10-year life the landfill area required to handle solid wastes generated for this site would be 10 ϫ 0.042 ϭ 0.42 acre (1699.7 m 2 , 0.17 ha); with a 20-year life the area required would be 20 ϫ 0.042 ϭ 0.84 acre (3399.3 m 2 ; 0.34 ha). As these calculations show, the area required for this landfill is relatively modest—less than an acre with a 20-year life. However, in heavily populated areas the waste generation could be significantly larger. Thus, when planning a sanitary landfill, the usual assumption is that each person generates 5 lb (2.26 kg) per day of solid waste. This number is based on an assumption of half the waste (2.5 lb; 1.13 kg) being from residential sources and the other half being from commercial and industrial sources. Hence, in a city having a population of 1-million people, the annual solid-waste generation would be 1,000,000 people ϫ 5 lb/day per person ϫ 365 days per year ϭ 1,825,000,000 lb (828,550,000 kg). Following the same method of calculation as above, the annual landfill space requirement would be V A ϭ 1,825,000,000/1100 ϭ 1,659,091 yd 3 (1,269,205 m 3 ). With a 20-ft (6-m) height for the landfill, the annual area required would be 1,659,091 ϫ 27/20 ϫ 43,560 ϭ 51.4 acres (208,002 m 2 ; 20.8 ha). Increasing the landfill height to 40 ft (12 m) would reduce the required area to 25.7 acres (104,037 m 2 ; 10.4 ha). A 60-ft high landfill would reduce the required area to 17.1 acres (69,334 m 2 ; 6.9 ha). In densely populated areas, landfills sometimes reach heights of 100 ft (30.5 m) to conserve horizontal space. This example graphically shows why landfills are becoming so much more ex- pensive. Further, with the possibility of air and stream pollution from a landfill, there is greater regulation of landfills every year. This example also shows why incineration of solid waste to reduce its volume while generating useful heat is so attractive to communities and industries. Further advantages of incineration include reduction of the possibility of groundwater pollution from the landfill and the chance to recover valuable minerals which can be sold or reused. Residue from incineration can be used in road and highway construction or for fill in areas need- ing it. Related Calculations. Use this general procedure for tentative choices of treat- ment technologies for cleaning up contaminated waste sites. The greatest risks faced by industry are where human life is at stake. Penalties are severe where human health is endangered by contaminated wastes. Hence, any expenditures for treatment equipment can usually be justified by the savings obtained by eliminating lawsuits, judgments, and years of protracted legal wrangling. A good example is the asbestos lawsuits which have been in the courts for years. To show what industry has done to reduce harmful wastes, here are results published in the Wall Street Journal for the years 1974 and 1993: Lead emissions declined from 223,686 tons in 1973 to 4885 tons in 1993 or to 2.2 percent of the original emissions; carbon monoxide emissions for the same period fell from 124.8 million tons to 97.2 million tons, or 77.9 percent of the original; rivers with fecal coliform above the federal standard were 31 percent in 1974 and 26 percent in Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. ENVIRONMENTAL CONTROL AND ENERGY CONSERVATION ENVIRONMENTAL CONTROL AND ENERGY CONSERVATION 18.9 FIGURE 1 Leachate seepage in landfill. (McGraw-Hill). 1994; municipal waste recovered for recycling was 7.9 percent in 1974 and 22.0 percent in 1994. The simplest way to dispose of solid wastes is to put them in landfills. This practice was followed for years, but recent studies show that rain falling on land- filled wastes seeps through and into the wastes, and can become contaminated if the wastes are harmful. Eventually, unless geological conditions are ideal, the con- taminated rainwater seeps into the groundwater under the landfill. Once in the groundwater, the contaminants must be treated before the water can be used for drinking or other household purposes. Most landfills will have a leachate seepage area, Fig. 1. There may also be a contaminant plume, as shown, which reaches, and pollutes, the groundwater. This Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. ENVIRONMENTAL CONTROL AND ENERGY CONSERVATION 18.10 ENVIRONMENTAL CONTROL is why more and more communities are restricting, or prohibiting, landfills. Engi- neers are therefore more pressed than ever to find better, and safer, ways to dispose of contaminated wastes. And with greater environmental oversight by both Federal and State governments, the pressure on engineers to find safe, economical treatment methods is growing. The suggested treatments in Table 2 are a good starting point for choosing suitable and safe ways to handle contaminated wastes of all types. Landfills must be covered daily. A 6-in (15-cm) thick cover of the compacted refuse is required by most regulatory agencies and local authorities. The volume of landfill cover, ft 3 , required each day can be computed from: (Landfill working face length, ft)(landfill working width, ft)(0.5). Multiply by 0.0283 to convert to m 3 . Since the daily cover, usually soil, must be moved by machinery operated by hu- mans, the cost can be significant when the landfill becomes high—more than 30 ft (9.1 m). The greater the height of a landfill, the more optimal, in general, is the site and its utilization. For this reason, landfills have grown in height in recent years in many urban areas. Table 2 is the work of David R. Hopper, Chemical Process Engineering Program Manager, ENSR Consulting and Engineering, as reported in Chemical Engineering magazine. CLEANING UP A CONTAMINATED WASTE SITE VIA BIOREMEDIATION Evaluate the economics of cleaning up a 40-acre (161,872 m 2 ) site contaminated with petroleum hydrocarbons, gasoline, and sludge. Estimates show that some 100,000 yd 3 (76,500 m 3 ) must be remediated to meet federal and local environ- mental requirements. The site has three impoundments containing weathered crude oils, tars, and drilling muds ranging in concentration from 3800 to 40,000 ppm, as measured by the Environmental Protection Agency (EPA) Method 8015M. While hydrocarbon concentrations in the soil are high, tests for flash point, pH, 96-h fish bioassay, show that the soil could be classified as nonhazardous. Total petroleum hydrocarbons are less than 500 ppm. Speed of treatment is not needed by the owner of the project. Show how to compute the net present value for the investment in alternative treatment methods for which the parameters are given in step 4 of this procedure. Calculation Procedure: 1. Compare the treatment technologies available A number of treatment technologies are available to remediate such a site. Where total petroleum hydrocarbons are less than 500 ppm, as at this site, biological land treatment is usually sufficient to meet regulatory and human safety needs. Further, hazardous and nonhazardous waste cleanup via bioremediation is gaining popular- ity. One reason is the high degree of public acceptance of bioremediation vs. al- ternatives such as incineration. The Resource Conservation and Recovery Act (RCRA) defines hazardous waste as specifically listed wastes or as wastes that are characteristically toxic, corrosive, flammable, or reactive. Wastes at this site fit certain of these categories. Table 3 compares three biological treatment technologies currently in use. The type of treatment, and approximate cost, $/ft 3 ($/m 3 ), are also given. Since petro- Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. ENVIRONMENTAL CONTROL AND ENERGY CONSERVATION [...]... 1.1 1.15 1 .23 1. 32 1.41 1. 52 1. 62 1.74 1 .86 2. 00 2. 14 1 .25 1.39 1.55 1.73 1.93 2. 16 2. 41 2. 69 3.00 3.35 1. 38 1. 62 1.90 2. 24 2. 45 3.09 3. 62 4 .26 5.00 5 .87 1. 58 2. 00 2. 51 3.16 3. 98 5.01 6.31 7.94 10.00 12. 59 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 20 06 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as... pp 1 38 175 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 20 06 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website 23 ϩ 62 ϩ100 ϩ 38 ϩ90 ϩ151 ϩ 38 ϩ90 ϩ151 0.3 ϩ41 ϩ 124 21 6 2 times 5 times 10 times 2 times 5 times 10 times Scaleup 0 .2 23 ϩ 62 ϩ100 ϩ15 ϩ 38 ϩ 58 0.4 ϩ15 ϩ 38 ϩ 58 ϩ7 ϩ17 26 ... concentration of hazardous gas inside the building cavity, use C ϭ Q / (1.5Uc)(Ap), where Uc ϭ the critical wind speed, m / s (ft / min); Ap ϭ cross-sectional area of the building perpendicular to the wind direction, m2 For this building, assuming a critical wind speed of 1 m / s (3 . 28 ft / s), and a crosssectional area of 10 m ϫ 5 m ϭ 50 m2 (5 38 .2 ft2), C ϭ 0. 526 g / s / [(1.5)(1 m / s)(50 m2)] ϭ 0.007... step 1 and multiply it by the ratio of today’s cost to the earlier cost Or, (C2) / (C1) ϭ (S2) / (S1)R(it / ie), where it ϭ today’s cost index; ie ϭ cost index at earlier date; other symbols as before Substituting, C2 ϭ $8, 600,000 (80 0,000 / 25 0,000)0.75( 387 / 325 ) ϭ $24 ,501 ,26 7; say $24 ,500,000 for discussion and comparison purposes Thus, the engineer making estimates of plant or facility costs can bring... using a table of compound interest factors for an interest rate of 12 percent, NPV, treatment A ϭ Ϫ$ 180 ,000 ϩ $60,000 / 0 .27 741 ϭ $36 , 28 6 In this relation, the cash flow for years 1, 2, and 3 repays the investment of $ 180 ,000 in the equipment Hence, the cash flow for the fourth year is the only one used in the NPV calculation For the second treatment method, B, NPV ϭ Ϫ$ 180 ,000 ϩ $ 180 ,000 / 0 .8 929 ϩ $30,000... ϩ7 ϩ17 26 Error in using 0.7, % 0 0 0 0.6 Error in using 0.6, % TABLE 5 Potential Errors from Using the 0.6 or 0.7 as Cost-Capacity Factors 0 0 0 Ϫ7 Ϫ15 21 0.7 Ϫ7 Ϫ15 21 Ϫ13 28 Ϫ37 0 .8 Ϫ13 28 Ϫ37 Ϫ19 Ϫ 38 Ϫ50 0.9 Ϫ19 Ϫ 38 Ϫ50 24 Ϫ47 Ϫ60 1.0 ENVIRONMENTAL CONTROL AND ENERGY CONSERVATION Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 20 06 The... Table 5 Thus, the ratio for (80 0,000 / 25 0,000)0.75 ϭ 2. 39 From the table, interpolating between R ϭ 0.7 and R ϭ 0 .8, gives a ratio of 2. 285 for a plant three times as large as the original plant The plant here is 3 .2 times (ϭ 80 0,000 / 25 0,000) Again, this is well within the accuracies met in early cost estimates A rule of thumb says that with R ϭ 0.6, doubling the size of a plant increases the cost... ENERGY CONSERVATION 18. 15 TREATMENT COST FOR COMBINED SLURRY BIOREACTOR-LANDFARM SYSTEM $1 38 $111 $/ton 120 $ 62 80 40 0 3 year 5 year Landfarm cost 10 year Slurry cost FIGURE 4 The treatment cost for this system reaches a minimum value after 5 years, then rises again (Carla Magazino and Chemical Engineering. ) Note that the costs given above are for a specific installation While they are not applicable... technologies of almost every other branch of the profession Thus, the environmental engineer will use methods and solutions from engineering disciplines including mechanical, civil, electrical, chemical, industrial, architectural, sanitary, nuclear, and control engineering Today a number of engineering schools are offering a major in environmental engineering Graduates have studied portions of the disciplines... plants that are not permitted to discharge to receiving bodies of water have often relied on solar evaporation ponds to dispose of this ‘‘unsuitable’’ water, especially in arid and semiarid regions The plant shown in Fig 5 is in the Orlando, FL area which has a particularly wet season from June through September Hence, evaporation ponds are not feasible Further, the plant site is not located near any major . 1.39 1. 62 2.00 0.4 1. 32 1.55 1.90 2. 51 0.5 1.41 1.73 2. 24 3.16 0.6 1. 52 1.93 2. 45 3. 98 0.7 1. 62 2.16 3.09 5.01 0 .8 1.74 2. 41 3. 62 6.31 0.9 1 .86 2. 69 4 .26 7.94 1.0 2. 00 3.00 5.00 10.00 1.1 2. 14 3.35. required area of 1363.6 ϫ 27 ft 3 /yd 3 ϭ 36 ,81 7 .2 ft 3 /20 ft high ϭ 184 0 .8 ft 2 (171.0 m 2 ), or 184 0.9 ft 2 /43,560 ft 2 /acre ϭ 0.0 42 acre (169.9 m 2 ; 0.017 ha) per year. With a 10-year life. ϩ41 ϩ 38 23 ϩ15 ϩ70Ϫ7 Ϫ13 Ϫ19 5 times ϩ 124 ϩ90 ϩ 62 ϩ 38 ϩ17 0 Ϫ15 28 Ϫ 38 10 times 21 6 ϩ151 ϩ100 ϩ 58 26 0 21 Ϫ37 Ϫ50 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright