Solid waste, increase

Every year the U.S. generates about 320 billion lb of what is called municipal solid waste, or postconsumer waste. About 85% of this trash is currently disposed of in landfills. Yet as the amount of solid waste increases—and the Environmental Protection Agency estimates that it will reach 380 billion lb by 2000—a third of the landfills are expected to close in the next five years. Many people are concerned that efforts to deal with the growing quantity of garbage are not moving fast enough. 

Of the 200 million tons of municipal solid waste collected in the United States in 1993 (1), 22% was recycled while 62% was placed in landfills and 16% incinerated (2). Plastics comprised 9.3% of these materials. The number of U.S. residential collection programs increased from 1,000 in 1988 to more than 7,000 involving more than 100 million people in 1993 (2). Approximate 1994 U.S. recycling rates are given in Table 1. 

Solid Wastes and Biomass Large and increasing quantities of solid wastes are a significant feature of affluent societies. In the United States in 1993 the rate was about 1.8 kg (4 lb) per capita per day or nearly 190 Tg (2.07 X 10 U.S. tons) per year, but the growth rate has slowed in recent years as recycling efforts have increased. Table 27-4 shows that the composition of miscellaneous refuse is surprisingly uniform, but size and moisture variations cause major difficulties in efficient, economical disposal. 

Tier 0 and Tier 1 costs are direct and indirect costs. They include the engineering, materials, labor, construction, contingency, etc., as well as waste-collection and transportation services (in many cases we simply transform an air pollution problem into a solid waste or wastewater problem that requires final treatment and disposal), raw-material consumption (increase or decrease), and production costs. Tier 2 and... 

The J 984 Federal Hazardous and Solid Waste Amendments (HSWA, pronounced "hiss-wa") to RCRA requires phasing-out land disposal of hazardous waste. Some of the other mandates of this law include increased enforcement authority for EPA, more stringent hazardous waste management standards, and a comprehensive underground storage tank program. 

The Solid ira.ste Disposal Act was passed in 1965 to address Ute problem of wlitit to do with the increasing amounts of solid wastes being generated. It was designed to ... 

Centrifugation is performed in a closed system and is therefore an excellent choice for treating volatile fluids. The liquid and solid are mechanically separated by centrifugal force. The removal of most of the liquid increases the solid concentration in, and reduces the volume of, the waste stream. The collected solid waste may then be treated and disposed of or recovered. Three types of units are available for centrifugation the solid bowl, the disk, and the basket. The first two are used in large plants, the third in smaller plants. 

Use of some biomass feedstocks can increase potential environmental risks. Municipal solid waste can contain toxic materials that can produce dioxins and other poisons in the flue gas, and these should not be burned without special emission controls. Demolition wood can contain lead from paint, other heavy metals, creosote, and halides used in presen a-tive treatments. Sewage sludge has a high amount of sulfur, and sulfur dioxide emission can increase if sewage sludge is used as a feedstock. 

In addition to the solid waste problem, we can also expect that with expanding population or expanding demands of a static population, there will be societal pressure to reduce material usage over and above cost factors. These pressures could result in legislation to expand the environmental protection philosophy. For example, since plant materials are a renewable resource as well as readily recyclable, we may expect forced increases in paper-based packages. 

Process problems include slag formation, ash removal, and process control because of the heterogeneous solid waste feed. These problems have been managed to some degree by "overdesigning" the plant, with the result that combustion of municipal solid waste is not economically competitive in areas where low-cost electricity or landfills for waste disposal are available. The future cost of electricity is difficult to predict. However, the steady decrease in the availability of landfills portends increasing use of this process to dispose of municipal wastes, particularly in large cities. 

This chapter attempts to provide an overview of the application of principles, outlined in previous chapters, to the bioremediation of contaminated terrestrial sites and the associated groundwater. Cardinal microbiological processes will be addressed only briefly, and references should be made to previous chapters for metabolic details. There are several reasons for the heightened concern over the increasing volume of solid waste—both industrial and domestic. On the positive side, however,... 

The quantity of materials required to sustain the lifestyle of the developed world is large and increasing. In the 1990s, Germans discovered that they consume about 76 tonnes of solid materials and 60 tonnes of domestic water per capita per annum to support their lifestyle. Only a small fraction of this is retained for any length of time. Most of it results in sewage, solid waste and atmospheric pollution. 

A solid waste, or combination of solid waste, which because of its quantity, concentration, or physical, chemical, or infectious characteristics may (a) cause, or significantly contribute to, an increase in mortality or an increase in serious irreversible, or incapacitating reversible, illness or (b) pose a substantial present or potential hazard to human health or the environment when improperly treated, stored, transported, or disposed of, or otherwise managed. 

Molecular chlorine should not be used in the process. The effluent should not result in a temperature increase of more than 3 °C at the edge of the zone where initial mixing and dilution take place. Where the zone is not defined, 100 m from the point of discharge should be used. Solid wastes should be sent to combustion devices or disposed of in a manner that avoids odor generation and the release of toxic organics to the environment. 

Alternative final cover systems, such as the innovative evapotranspiration (ET) cover systems, are increasingly being considered for use at waste disposal sites, including municipal solid waste (MSW) and hazardous waste landfills when equivalent performance to conventional final cover systems can be demonstrated. Unlike conventional cover system designs that use materials with low hydraulic permeability (barrier layers) to minimize the downward migration of water from the cover to the waste (percolation), ET cover systems use water balance components to minimize percolation. These cover systems rely on the properties of soil to store water until it is either transpired through vegetation or evaporated from the soil surface. 

Long-range atmospheric transport of Hg from fossil fuel combustion and solid waste incineration has increased Hg in freshwater and biota. In the United States, combustion of fossil fuels for power generation is estimated to generate about 30% of the total release of Hg into the atmosphere (Harriss and Hohenemser, 1978). One in every three lakes in the United States and nearly one-quarter of the nation s rivers contain various pollutants, including Hg (CNN, 2004). Forty States in the U.S. have issued advisories for methylmercury on selected water-bodies, and 13 states have statewide advisories for some or all sportfish from rivers or lakes (USGS, 2000). Fish consumption advisories for methylmercury account for more than three-quarters of all fish consumption advisories. 

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