CHAPTER 11TOWARD A GREENER ANTHROSPHERE THROUGH

INDUSTRIAL ECOLOGY

From Green Chemistry and the Ten Commandments of Sustainability, Stanley E. Manahan, ChemChar Research,

Inc., 2006manahans@missouri.edu

11.1. INDUSTRIAL ECOLOGY AND INDUSTRIAL ECOSYSTEMS

The anthrosphere has been defined as a fifth sphere of the environment.Industrial ecology integrates the principles of science, engineering, and ecology in industrial systems through which goods and services are provided in a way that minimizes environmental impact and optimizes utilization of resources, energy, and capital

• Every aspect of the provision of goods and services from concept, through production, and to the final fate of products remaining after use

• A sustainable means of providing goods and services• Most successful when it mimics natural ecosystems

Industrial EcosystemAn industrial ecosystem functions through groups of industrial concerns, distributors, and other enterprises functioning to mutual advantage, using each others’ products, recycling each others’ potential waste materials, and utilizing energy as efficiently as possible to maximize

Market value of products

An industrial ecosystem is illustrated on the following slideIndustrial symbiosis is the development of such mutually advantageous interactions between two or more industrial enterprises that cause an industrial ecosystem to develop in the first place• Required for recycling

Consumption of material and energy

Major Components of an Industrial Ecosystem Showing Maximum Flows of Material and Energy Within the System

Scope of Industrial EcologyRegional scope large enough to encompass several industrial enterprises, but small enough for them to interact with each other on a constant basisFrequently based around transportation systems such as segments of interstate highways

11.2. METABOLIC PROCESSES IN INDUSTRIAL ECOSYSTEMS

Industrial metabolism refers to the processes to which materials and components are subjected in industrial ecosystems• Analogous to the metabolic processes that occur with food and

nutrients in biological systemsIndustrial metabolism may be addressed at several levels• Green chemistry at the molecular level where substances are

changed chemically to give desired materials or to generate energy• Within individual unit processes in a factory• At the factory level• At the industrial ecosystem level• Even globally

Wastes and Industrial EcologyWastes in natural and industrial ecosystemsIn natural ecosystems true wastes are virtually nonexistent• Waste plant biomass forms soil humusAnthropospheric industrial systems have developed in ways that generate large quantities of wastes• Industrial waste may be defined as dissipative use of natural

resources.• Human use of materials has a tendency to dilute and dissipate

materials and disperse them to the environment• Materials may end up in a physical or chemical form from which

reclamation becomes impractical because of the energy and effort required

• A successful industrial ecosystem overcomes such tendencies

Minimization of Byproduct and WasteThe objective of industrial metabolism in a successful industrial ecosystem is to make desired goods with the least amount of byproduct and wasteConsider production of lead from lead ore for the production of storage batteries

The recycling pathway for lead production takes essentially pure lead from recycled batteries and simply melts it down to produce lead for new batteries

• Mining large quantities of ore• Extracting the relatively small fraction of the ore consisting of lead

sulfide mineral• Roasting and reducing the mineral to get lead metal• These processes generate large quantities of lead-contaminated

tailings left over from mineral extraction and significant quantities of byproduct sulfur dioxide, which must be reclaimed to make sulfuric acid and not released to the environment

Comparison of Natural Ecosystems and Current Industrial Systems

• The basic unit of a natural ecosystem is the organism, whereas that of an industrial system is the firm

• Natural ecosystems handle materials in closed loops whereas with current practice, materials traverse an essentially one-way path through industrial systems

• Natural systems completely recycle materials, whereas in industrial systems the level of recycling is often very low

• Organisms have a tendency to concentrate materials such as CO2 from air concentrated in biomass whereas industrial systems tend to dilute materials to a level where they cannot be economically recycled, but still have the potential to pollute.

• The major function of organisms is reproduction whereas the main function of industrial enterprises is to generate goods and services

Natural Ecosystems and Current Industrial Systems (Cont.)

• Reservoirs of needed materials for natural ecosystems are essentially constant (oxygen, carbon dioxide, and nitrogen from air as examples) whereas industrial systems are faced with largely depleting reservoirs of materials (essential mineral ores)

• Recycling gives essentially constant reservoirs of materials

Regulation in Natural and Industrial EcosystemsBiological systems have elaborate means of control.Entire ecosystems are self-regulating.Industrial systems do not inherently operate in a self-regulating manner that is advantageous to their surroundings, or even to themselves.Failure of self-regulation of industrial systems• Have wastefully produced large quantities of goods of marginal

value• Running through limited resources in a short time• Dissipating materials to their surroundings• Polluting the environmentIndustrial ecosystems can be designed to operate in a self-regulating manner• Best under conditions of maximum recycling in which the system

is not dependent upon a depleting resource of raw materials or energy

Level of Recycling and Embedded Utility

Source of raw materialMaterialFabricationAssemblyProductLow-level recyclingHigh-level recycling

Quantity of materials and energy involved

11.3. LIFE CYCLES IN INDUSTRIAL ECOSYSTEMSIn a system of industrial ecology the entire life cycle of the product is considered as part of a life-cycle assessment.• To determine, measure, and minimize environmental and resource

impacts of products and services.Scope of the assessment• Time period •Space• Kinds of materials, processes, and products in the assessment

Example of Scope in Life Cycle AssessmentExample of the manufacture of an insecticide that releases harmful vapors and generates significant quantities of waste material• A narrowly focused assessment might consider control measures to

capture released vapors and the best means of disposing of the waste byproducts

• A broader scope would consider a different synthetic process that might not cause the problems mentioned

• An even broader scope might consider whether or not the insecticide even needs to be made and used; perhaps there are more acceptable alternatives to its use.

Life Cycle Assessment• Inventory analysis to provide information about the consumption

of material and release of wastes from the point that raw material is obtained to make a product to the time of its ultimate fate

• Impact analysis that considers the environmental and other impacts of the product

• Improvement analysis to determine measures that can be taken to reduce impacts

In doing life-cycle assessments consider three major categories• Products: Things and commodities that consumers use• Processes: Ways in which products are made• Facilities consisting of the infrastructural elements in which

products are made and distributed

Example of Life Cycle Assessment

Example of paper product• The environmental impact of paper product tends to be relatively

low. Even when paper is discarded improperly; it does eventually degrade without permanent effect.

• Process of making paper, beginning with harvesting of wood and continuing through the chemically intensive pulping process and final fabrication has significant environmental impact

FacilitiesHighly variable impact of facilities• Brownfields to describe sites of abandoned industrial facilities• Challenge to decomission sites of nuclear power reactors in which

there is a significant amount of radioactivity to deal with in dismantling and disposing of some of the reactor components

• Facilities can be designed with eventual decommissioning in mind• Structure flexibility of commercial buildings

Product Stewardship• Laser printer cartridges • Automobile batteries• Disincentive of disposal fee for automobile tires• Leasing • Deposits

11.4. KINDS OF PRODUCTSConsumable products such as laundry detergentsRecyclable commodities such as motor oilService products such as washing machineConsumable products are dispersed to the environment• Nontoxic • Not bioaccumulative • DegradableRecyclable commodities should be designed with durability and recycling in mind• Not as degradable as consumables

Service ProductsService products are designed to last for relatively long times, but should be recyclable• Channels through which such products can be recycled• Proposed “de-shopping” centers where items such as old

computers and broken small appliances can be returned for recycling

• Designed and constructed to facilitate disassembly so that various materials can be separated for recycling.

11.5. ATTRIBUTES REQUIRED BY AN INDUSTRIAL ECOSYSTEM

Key attributes of energy, materials, and diversityEnergyWith enough energy, almost anything is possible

• Consuming abundant fossil energy resources would cause unacceptable global warming effects

• Solar energy and wind energy are renewable sources of energy but are intermittent nature and require large areas of land in order to provide a significant share of energy needs

• Nuclear power facilities can provide abundant reliable energy, but present waste problems

Cogeneration and Combined Power CyclesCogeneration employing combined power cycles (next slide)

represents the most efficient energy use within an industry or within an industrial ecosystem

(1) Electricity generation(2) Steam used in processing(3) Steam and hot water used for heating• Burning fuels in large turbines connected to an electrical generator

and using the hot exhaust from the turbine to raise steam can double the overall efficiency of energy utilization.

• Using the cooled steam from the steam turbine for heating can further increase the overall efficiency of the energy utilization process.

Combined power cycles use energy with great efficiency through several levels as shown below:

Combined Power Cycles

MaterialsUtilization of materialsDematerialization in which less material is used for a specific purpose• Example: Less copper in 12 volt automobile electrical systemsSubstitution of abundant materials for scarce ones• Solid state circuits in radios or televisions

Recycling and Waste MiningRecycling• Wood and paper, which are not scarce, but recycling is advisable• Metals, especially scarce and valuable ones such as chromium,

platinum, and palladium• Parts and apparatus that can be refurbished and reusedWaste mining: Needed materials extracted from wastes• Combustible methane gas from municipal refuse landfills• Aluminum from finely divided coal fly ash generated in coal

combustion

Diversity in Industrial EcosystemsDiversity imparts a robust character to industrial ecosystems, which means that if one part of the system is diminished, other parts will take its place and keep the system functioning well• Example: Diverse energy sources to reduce vulnerability to

interruptions in power and energy supplies• Example: Diverse food sources to reduce vulnerability to reliance

on one food source for diet

The Kalundborg Industrial Ecosystem

ASNAESelectricalpower plantStatoilpetroleumrefinerySteamFuelgasCoolingwaterKemirasulfuricacid plantGreenhousesHomesFishfarm

Novo Nordiskpharmceuticals

Steam heatSludge fertilizerGyprocwallboardCalciumsulfateCement,roadmaterialCoal, limeCrude oil

Lake Tissowater

11.7. ENVIRONMENTAL IMPACTS OF INDUSTRIAL ECOSYSTEMS

The practice of industrial ecology in the anthrosphere affects the atmosphere, hydrosphere, geosphere, and biosphere.Emission to the atmosphere of pollutant gases, vapors from volatile compounds, particles and greenhouse warming carbon dioxideLarge quantities of water that may become polluted or warmed excessively when used for cooling (thermal pollution).Disruption of the geosphere from mining, dredging, and pumping of petroleum and other extractive activitiesDetrimental effects to the biosphere by release of toxic substancesGreenhouse-warming carbon dioxide emissions, acid gas emissions, smog-forming hydrocarbons and nitrogen oxides, and deterioration of atmospheric quality from particles released from fossil fuel combustion

Environmental Effects of Agricultural ActivitiesSome of the environmental effects of agricultural activities include• Replacement of entire, diverse biological ecosystems with artificial

ecosystems, which causes a severe disturbance in the natural state of the biosphere

• Loss of species diversity• Greenhouse-warming methane from rice paddies and from

livestock digestive systems• “Slash and burn” agricultural techniques practiced in some tropical

countries• Water used for irrigation, water salinity• Transgenic crops and livestock may have profound effects

Design of Industrial Ecosystems to Minimize Environmental Impact

Recycling materials, especially those extracted from the geosphereSelection of materials, such as silica fiber optic cables in place of copperMinimization of emission of volatile organic compoundsComplete water recycleTotally eliminate wastes requiring land disposalMost efficient use of the least polluting sources of energy possibleDesign of buildings to reduce heating and cooling costsCombined power cycles along with the generation of electricity

11.8. GREEN CHEMISTRY IN THE SERVICE OF INDUSTRIAL ECOSYSTEMS

Percent atom economy =Total mass of reactants

Use of nontoxic chemicals and processesConsideration of the chemical reactions and processes by which chemicals are manufactured

• Use existing chemical synthesis processes but make the process itself safer and less polluting while also making the reagents required for it by greener processes

• Use different reagents for the synthesis that are safer and less likely to pollute.

Total mass of product

Hazard ReductionExposure reduction has emphasized protective measures• At a personal level, safety glasses• At an industry level, end-of-pipe measures, such as scrubbers on

stacks• Command and control refers to regulations that apply primarily

to processes that have inherent dangers or that produce pollutants.• End-of-pipe measures are applied to the removal of pollutants and

wastes that are produced in a process, rather than their elimination within the process itself.

Green chemistry relies on hazard reduction• Know what the hazards are and where they originate• Toxicity hazards• Hazards associated with uncontrolled events such as fires and

explosions

Toxic SubstancesToxic substances classified according to biochemical properties that lead to toxic responses• Structure activity relationships, which use computer programs to

find correlations between features of chemical structure, such as groupings of functional groups, and the toxicity of the compounds

• Example: Compounds containing the N-N=O functional group are N-nitroso compounds, a family noted for members that cause cancer

Chemicals to Eliminate in Reducing Toxicity HazardsThree kinds of chemicals have a high priority in eliminating the toxicity hazards in green chemistry1. Heavy metals, such as lead, mercury, and arsenic (a metalloid)2. Lipid-soluble organics that are not readily degraded and may

undergo biomagnification in moving through a food chain3. Volatile organic compounds (VOCs, below):

CCl

ClCl

HCH

H

HC

H

HC

H

HC

H

HC

H

HC

H

HC

H

HCH

Heptane Trichloroethylene

Hazardous, Reactive ChemicalsChemicals that pose hazards because of their potential to undergo destructive chemical reactions• Combustible or flammable substances

• Oxidizers, such as ammonium perchlorate, NH4ClO4, that provide sources of oxygen for the reaction of reducers

• Reactive substances such as explosive nitroglycerin

4C3H5N3O9 12CO2 + 10H2O + 6N2 + O2 (11.8.1)• Corrosive substances that attack materials, including even human

flesh because they are strong acids, bases, or oxidizing agents

11.9. FEEDSTOCKS, REAGENTS, MEDIA, AND CATALYSTS

The main components of a chemical process• Feedstocks that are converted to final product• Reagents that act upon feedstocks• Media in which reactions occur• Catalysts that enable reactions to occur

FeedstocksThree major components of the process by which raw materials from a source are obtained in a form that can be utilized in a chemical synthesis1. Source of the feedstock

• Depleting resource, such as petroleum• Recycled materials• Renewable resources, particularly from materials made by

photosynthesis and biological processes.2. Separation and isolation of the desired substance

• Often the most environmentally harmful because of the relatively large amount of waste material that must be discarded in obtaining the needed feedstock.

3. Chemical processes that give the final product by reactions upon feedstocks by various kinds of reagents in media such as organic solvents, often using catalysts.

Reagents

A reagent is a substance that converts feedstocks to new chemicals• High product selectivity• High product yieldAlternative reagents are often important in green chemistry

Oxidation and Oxidation ReagentsOxidation reagents add oxygen to a chemical compound or a functional group on a compoundExample:

• Oxidation often uses dangerous reagents, such as potassium dichromate, K2Cr2O7

• Green chemistry tries to use safer molecular oxygen (O2), ozone (O3), and hydrogen peroxide (H2O2) usually used with a suitable catalyst or catalyzed by enzymes

• Organisms carry out biochemical oxidations under mild conditions using monooxygenase and peroxidase enzymes that catalyze the oxidizing action of molecular oxygen or hydrogen peroxide

OHCO

CH

H

HOH

H

HC

H

HCH + H2O (11.9.1) + 2{O}

Ethanol Acetic acid

ReductionReduction consisting of loss of O, gain of H, or gain of electrons

• Hazardous reductants such as lithium aluminum hydride (LiAlH4) and tributyltin hydride.

Electrical currents can be used for oxidation and reduction without reagents:

Alkylation

Alkylation for attachment of alkyl groups especially -CH3

• Commonly performed with dimethyl sulfate reagent

HR N

CH3

CH3H3C O S

O

O

OH

NH

R +2 + 2NaOH

2 + Na2SO4 + 2H 2O (11.9.3)Dimethyl sulfate

• Dimethyl sulfate may be carcinogenic• As an alternative, use dimethyl carbonate

(11.9.4)NCH3

HR

CH3C

O

H3C O ONH

HR

OHH

H

H

C

Dimethyl carbonate+2

2 + CO2 +

MediaMedia in which reactions occurUsually organic solvents or waterProvide a medium in which feedstocks and reagents can dissolve and come into close, rapid contact at the molecular level• Water is safest, but may not work for organic materials• Hydrocarbon solvents may burn, explode or be toxicReplace solvents with less hazardous ones, such as benzene (which may cause leukemia) by toluene

Replace straight-chain hydrocarbon n-hexane, which can cause peripheral neuropathy, with branched-chain 2,5-dimethylhexane, which is not very toxicNonpolar organic solvents suspended as colloidal particles can be used as mediaSupercritical carbon dioxide at high pressure and elevated temperature can act as media

CH3

Benzene Toluene

Ionic LiquidsIonic liquids such as the one shown below have been used as media for some reactions:

H

H

H

CC

H

H

C

H

H

N NH3C C

H

H1-Butyl-3-methylimidazolium hexafluorophosphate

-

P

FF

FF

F

F+

Solvent-free reactions have been used with some success

CatalystsCatalysts are substances that speed reactions without being consumed themselvesHeterogeneous catalysts that are held upon some sort of support where they interact with reactants• Readily separated from reaction productsHomogeneous catalysts that are actually mixed with the reactants• Often work better because of intimate contact with reagents• Require separation and may contaminate productAn objective of green chemistry is to develop heterogeneous catalysts that equal homogeneous catalysts in their performance

Enhancement of Catalyst SelectivitySelectivity enhancement of catalysts is desirableLower energy requirements and less severe, safer conditions with appropriate catalystsEnzyme-catalyzed green chemical processes including those with transgenic organismsSynthetic catalysts that mimic enzyme action such as the one shown below that mimics iron-based enzymes

+ H2O2

N N

NN Fe

CH

RH

C

O

H

Alkene (R is an unspecifiedorganic group

Catalyst of N,N'-dimethyl-N,N'bis(2-pyridyl-methyl)ethylenediamine bonded to Fe 2+ ion

Epoxide group attached byoxidation at C=C bond

CH

RH

HC