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Ch1 Overview

Ch1 Overview. 1.A What Is Environmental Engineering Science? Use of Earth’s Resource, Release Contaminants to Environment, Environmental Impact Constituents, Impurities , Species, Contaminants , Pollutants

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Ch1 Overview

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  1. Ch1 Overview • 1.A What Is Environmental Engineering Science? • Use of Earth’s Resource, Release Contaminants to Environment, Environmental Impact • Constituents, Impurities, Species, Contaminants, Pollutants • Instead, the central mission of environmental engineering is to develop and applyscientific knowledgethrough technology to minimize adverse effects that are associated withcontaminants inenvironmental media. Environmental Engineering Science

  2. 何謂環境工程科學？ • 環境工程與其他工程技術之不同處。 • 資源之利用與污染物之控制。 • 污染物控制之發展歷史常涉及人或環境之傷害。 • 空氣污染、水污染、有害物質污染… • USEPA 1970年代成立 … • 台灣環保署 1987年成立 … Environmental Engineering Science

  3. Use of Earth’s Resource Release Contaminants to Environment Environmental Impact Environmental Engineering Science

  4. Constituents Impurities, Species Contaminants Pollutants Environmental Engineering Science

  5. Apply scientific knowledge The central mission of environmental engineering Technologies Minimize adverse effects of contaminants Environmental Engineering Science

  6. 環境流體：水、空氣 • 污染物名詞定義：pollutants, contaminants… • 污染物處理與控制之目標？ • 天然污染與人為污染，理想與現實。 • 環境品質標準與環境排放標準。 • 水體用途標準與放流水標準。 • 空氣品質標準與空氣污染物排放標準。 Environmental Engineering Science

  7. 1.B Domains of Environmental Engineering • 1.B.l Water Quality Engineering • 1.B.2 Air Qua1ity Engineering • 1.B.3 Hazardous Waste Management Environmental Engineering Science

  8. 1.B.l Water Quality Engineering • Water treatment, Wastewater treatment • Water Treatment • For drinking, for industry, for agriculture • Water Quality • Contaminants fate and transport, aquatic ecology, urban runoff …… • Filtration and chemical disinfection • Wastewater treatment • Health problem and poor sanitation • Physical, chemical and biological treatment • Organic, inorganic and nutrient removal Environmental Engineering Science

  9. 自來水淨水工程與廢水處理工程，水再生處理之發展。自來水淨水工程與廢水處理工程，水再生處理之發展。 • 淨水：飲用、工業用、農業用… • 廢水：環境衛生、預防疾病 (1854年, 10,000 死亡) • 過濾、消毒(UV/加氯/臭氧) • 再來水管線、下水道管線、再生水管線。 • 發展趨勢：微量污染物、環境賀爾蒙、傳輸宿命、 Environmental Engineering Science

  10. 飲用水法案、污染物種類眾多… • 有機化合物、無機化合物、放射性物質、微生物。 • 點污染源、非點污染源。 Environmental Engineering Science

  11. Seletar • 22,700cmd • 2004 • Kranji • 54,600cmd • Jan 2003 • Bedok • 27,300cmd • Jan 2003 • Ulu Pandan • 145,500cmd • Early- 2007 • Legend • NEWater pipeline • NEWater Plant • Service Reservoir • 新加坡NEWater市場規模 • 現行4都市廠產水250,000 cmd主要為工業用水補充。

  12. 美國水再生利用案例-南加州西流域 • 12 • 12

  13. Environmental Engineering Science

  14. 1.B.2 Air Qua1ity Engineering • Industries and motor vehicles • Point source, non-point source • Particulates, sulfur oxides, nitrogen oxides, hydrocarbon, ozone, lead • Acid deposition, Ozone depletion, Hazardous Air Pollutants, Biomass cookstoves. Environmental Engineering Science

  15. 不完全燃燒之空氣污染。 • 工業排放之空氣污染。 • 光化學煙霧、酸雨、CFC臭氧層破壞、189種有害空氣污染物… • CO2問題。 Environmental Engineering Science

  16. 1.B.3 Hazardous Waste Management • Synthetic organic chemicals and natural organic chemicals • US federal legislation “hazardous” • Corrosivity, ignitability, reactivity, toxicity • Specific operations, no precise boundary • Hazardous waste management • Prevention and remediation Environmental Engineering Science

  17. 1.C Context and Concepts • 1.C.l Concentrations and Other Units of Measure • 1.C.2 Material Balance • 1.C.3 Factors Governing Contaminant Concentrations • 1.C.4 Engineering Analysis • 1.C.5 Control Opportunities • 1.C.6 Environmental Regulations • 1.C.7 Precision and Accuracy • 1.C.8 Magnitudes: Length Scales and Characteristic Times Environmental Engineering Science

  18. 1.C.1 Concentrations and Other Units of Measure • Concentration Amounts are commonly quantified either by mass or by moles, where one mole is equal to Avogadro’s number of elements: Nav=6.02×1023. 1 mole of carbon has a mass of 12.0 grams, and 1 mole of carbon dioxide (CO2) has a mass of 12.0+2×16.0=44.0 grams. Environmental Engineering Science

  19. 單位：Dalton, 莫爾(mole) • 濃度表示方式：重量濃度、莫爾濃度、當量濃度。 • 重量比或莫爾比：ppm, ppb • 水處理領域中 ppm 為重量比。 • 空氣處理領域 ppm 為莫爾筆、體積比。 • 濃度換算：分子量 Environmental Engineering Science

  20. A special unit is defined for concentration of charge associated with ions in water. We refer to the ionic charge concentration associated with some species as its normality (N), measured in units of equivalents per liter (eq L-1), where one equivalent represents a net charge equal to one mole of electrons. Environmental Engineering Science

  21. Mass Fraction and Mole Fraction ％percent 1 part species per 100 part solution ‰ per mil 1 part species per 1000 part solution ppm part per million 1 part species per 106 part solution ppb part per billpon 1 part species per 109 part solution ppt part per trillion 1 part species per 1012 part solution Environmental Engineering Science

  22. Thus, 5 ppb of benzene in air means that there are 5×10-9 moles (3×1015 molecules) of benzene in a mole of air; on the other hand, 5 ppb of benzene in water means that 1g of water contains 5×10-9 g of benzene. Environmental Engineering Science

  23. 1.C.2 Material Balance Material balances are applied for both conserved and nonconserved properties of matter. An example of a conserves property is chemical element. • Conserved properties are not changed by transformation processes. Chemical reactions do not change the amount of a chemical element in a system. • An example of a nonconserved property is a chemical compound, since reactions change the quantities of compounds. Environmental Engineering Science

  24. 1.C.3 Material Balances on Flows • A wastewater stream containing a contaminant concentration Cw flows at a volumetric rate Qw into a river. Upstream of the discharge, the contaminant concentration in the river is Cr and the volumetric flow rate of water is Qr. Assuming complete mixing of the wastewater stream in the river at the point of discharge, what is the contaminant concentration immediately downstream? Environmental Engineering Science

  25. 1.C.3 Material Balances on Flows Environmental Engineering Science

  26. 1.C.3 Material Balances on Flows • SOLUTION： Qmix=Qr+Qw QmixCmix= QrCr + QwCw • Therefore, Cmix = (QrCr + QwCw )/ (Qr+Qw) • The concentration of contaminants does not change in the fluid streams as they diverge, so the composition of each branch is the same as in the entering branch. Environmental Engineering Science

  27. Transformation processes Removal mechanisms Transport processes Sources Concentrations Adverse effects 1.C.3 Factors Governing Contaminant Concentrations Environmental Engineering Science

  28. 1.C.4 Engineering Analysis • Analysis is at the heart of environmental engineering science. We analyze both engineered and natural environmental systems, usually for one of two major purposes: to predict how they will behave or to explain why they behaved as they did. • Analyses may be conducted at several levels, from simple range-finding Environmental Engineering Science

  29. 1.C.4 Engineering Analysis • Steps： 1.Translate the physical system into a mathematical representation. 2.Solve the mathematical problem to obtain the result. 3.Interpret the significance of the result for the physical system. Environmental Engineering Science

  30. 1.C.5 Control Opportunities • In the past, the major solution to pollution is dilution. • Human activities have reached a scale that is sufficient to causeregional and even global environmental impact. It is certainly no longer the case that dilution suffices to solve environmental quality problems. Environmental Engineering Science

  31. 1.C.5 Control Opportunities • The activity that generates the waste is the first link in this chain. • The next opportunity occurs when waste is present • The final opportunity occurs after the waste has been released to the environment. Environmental Engineering Science

  32. 1.C.5 Control Opportunities • Applying pollution control measures at the generating process is known as pollution prevention. • Control measures applied after the waste has been generated but before it is discharged are termedend-of-the-pipetreatment processes. • Corrective measures applied after the waste has been released are known asenvironmental restoration. Environmental Engineering Science

  33. 1.C.5 Control Opportunities • In water quality engineering, environmental control is most frequently applied at two points: • to water before it is delivered to the consumer • to wastewater before it is released to the environment • Air pollutants control methods focus on the effluent streams that may lead to airborne release of pollutants. Environmental Engineering Science

  34. 1.C.6 Environmental Regulations • Most environmental engineering activities are directly or indirectly motivated by environmental regulations. • Pollutant regulations are based on technical information concerning : • health effects and other environmental costs of pollution. • technology and cost of control. Environmental Engineering Science

  35. 1.C.6 Environmental Regulations • The political process is made complex by many factors, two prominent ones being : • that the technical information is incomplete, uncertain, and sometimes conflicting • that interest groups seek to influence the decision. Environmental Engineering Science

  36. 1.C.7 Precision and Accuracy Environmental Engineering Science

  37. 1.C.8 Magnitudes: Length Scales and Characteristic Times Environmental Engineering Science

  38. Characteristic residence time (r ) • Hydraulic detention time • r  S/F0 • t << r • t  r • t >> r Environmental Engineering Science

  39. 停留時間、反應時間。 • 重要之設計與操作指標。 • 特徵停留時間、空槽停留時間、空塔停留時間、水力停留時間、污泥停留時間。 • 特徵停留時間之意涵：反應狀態、平衡達成狀態、污染物濃度改變情形。 Environmental Engineering Science

  40. Problem Assignments #1 • 1. Unit conservation exercises and exposure pathway (1.2 in the text) • 2. A water resource problem (1.8 in the text) • 3. Characteristic times and urban air quality (1.9 in the text) Environmental Engineering Science

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