Environmental Problems, Their Causes, and Sustainability 1

These new landfills are equipped with a connectednetwork of vent pipes to collect landfill gas(consisting mostly of two greenhouse gases, methaneand carbon dioxide) released by the underground decompositionof wastes. The methane is filtered out andburned in small gas turbines to produce steam or electricityfor nearby facilities or sold to utilities for use asa fuel. In the United States Waste Management has decidedthat producing and selling power from methaneproduced by decomposing garbage in its many landfillsis a major business opportunity. Figure 24-15 liststhe advantages and disadvantages of using sanitarylandfills to dispose of solid waste.Thousands of older and abandoned landfills in theUnited States (and elsewhere) do not have gas collectionsystems and will emit methane and carbon dioxide,both potent greenhouse gases, for decades.Contamination of groundwater and nearby surfacewater by leachate from unlined and lined olderlandfills is also a serious problem. Some 86% of olderAdvantagesNo open burningLittle odorLowgroundwaterpollution if sitedproperlyCan be builtquicklyLow operatingcostsCan handlelarge amountsof wasteFilled land canbe used forotherpurposesNo shortage oflandfill space inmany areasTrade-OffsSanitary LandfillsDisadvantagesNoise and trafficDustAir pollution fromtoxic gases andvolatile organiccompoundsReleasesgreenhouse gases(methane and CO 2 )unless they arecollectedGroundwatercontaminationSlow decompositionof wastesDiscouragesrecycling and wastereductionEventually leaks andcan contaminategroundwaterFigure 24-15 Trade-offs: advantages and disadvantagesof using sanitary landfills to dispose of solid waste. Pick thesingle advantage and disadvantage that you think are the mostimportant.U.S. landfills studied have contaminated groundwater,and a fifth of all Superfund hazardous waste sites areformer municipal landfills. In other words, most olderlandfills throughout the world are chemical timebombs that release greenhouse gases and can eventuallyleak hazardous chemicals.xHOW WOULD YOU VOTE? Do the advantages of buryingsolid waste in sanitary landfills outweigh the disadvantages?Cast your vote online at http://biology.brookscole.com/miller14.24-7 HAZARDOUS WASTEWhat Is Hazardous Waste? ToxicThreatsDeveloped countries produce about 80–90%of the world’s solid and liquid wastes that canharm people, and most such wastes are notregulated.Hazardous waste is any discarded solid or liquid materialthat is toxic, ignitable, corrosive, or reactive enoughto explode or release toxic fumes. According to the UNEnvironment Programme, developed countries produce80–90% of these wastes.In the United States, about 5% of all hazardouswaste is regulated under the Resource Conservationand Recovery Act (RCRA, pronounced “RICK-ra”)and is often referred to as RCRA hazardous waste. RCRAdoes not regulate■ Radioactive wastes■ Hazardous and toxic materials discarded byhouseholds (Figure 24-16)■ Mining wastes■ Oil- and gas-drilling wastes (routinely dischargedinto surface waters or dumped into unlined pits andlandfills)■ Liquid waste containing organic hydrocarboncompounds (80% of all liquid hazardous waste) cementkiln dust produced when liquid hazardouswastes are burned in a cement kiln■ Wastes from the thousands of small businesses andfactories that generate less than 100 kilograms (220pounds) of hazardous waste per monthAbout 72% of these hazardous wastes are producedby chemical and petroleum industries andanother 22% are generated by mining and metal processingindustries.The amount of hazardous and toxic waste in theUnited States and other countries is likely to increasebecause of the projected 80% global increase in chemical548 CHAPTER 24 Solid and Hazardous Waste