Waste disposal routes

Schematic of material chains related to plastics, from production to waste disposal routes...

According to APME, energy recovery should be the preferred waste disposal route for polymeric materials that are very contaminated, bonded, laminated to other materials, or are at the end of their performance with respect to their physical/chemical properties. This paper takes a detailed look at energy recovery from municipal solid waste combustors, and considers the effect of polymeric materials. 

Compounds that are endocrine disrupters include natural animal hormones released into the environment, plant toxins or phytoestrogens, synthetic hormones present in sewage water and used for medical treatment (e.g., diethylstilbestrol), and several chemicals, including some pesticides and polychlorinated biphenols (PCBs). Endocrine disrupters enter the environment often as a by-product of many chemical and manufacturing processes and through waste disposal routes. Some evidence now suggests that effects of thyroid hormones and the immune system occur in addition to the disruptions of hormones that play a major part in the control of reproduction and development. 

Where hazardous chemical(s) are used they should be assessed to determine the impact on the environment. Such an assessment should also consider the effect of intermediates and breakdown products that may be produced. The assessment should include consideration of the effect of the materials on the atmosphere, the sewage treatment system, controlled waters, land and groxmdwater, and waste disposal routes. The risk assessment should include an estimation of the risk from the hazardous materials, the magnitude of the effects, and the probability of an occurrence. Included should be an evaluation of the significance of the hazards and the consequences should the environment be affected. It is a structured approach to setting priorities for controlling the hazards. The risk assessment will provide iiiformation of where control measures will need to be applied to prevent an impact on the environment. 

Manufacture Various methods for the manufacture of acrylates are summarized in Figure 1, showing thek dependence on specific raw materials. For a route to be commercially attractive, the raw material costs and utilization must be low, plant investment and operating costs not excessive, and waste disposal charges minimal. 

Some alkylphenol appHcations can tolerate "as is" reactor products, most significantly in the production of alkylphenol—formaldehyde resins. These resins can tolerate some of the reactant and by-product from the alkylphenol reactor because they undergo purification steps. This resin production route has both capital and operating cost advantages over using purer alkylphenol streams as feedstock. For these savings, the resin producer must operate the process in such a way as to tolerate a more widely varying feedstock and assume the burden of waste disposal of some unreactive materials from the alkylphenol process. 

Selection of appropriate disposal routes for liquids/solids to comply with acceptable discharge levels Disposal of toxic waste... 

The cost of depositing waste on controlled landfill sites is relatively cheap. However, the expense of road transport to suitable sites generally limits this disposal route to relatively low-volume applications. 

The most important routes of exposure to endosulfan for the general population are ingestion of food and the use of tobacco products with endosulfan residues remaining after treatment. Farmers, pesticide applicators, and individuals living in the vicinity of hazardous waste disposal sites contaminated with endosulfan may receive additional exposure through dermal contact and inhalation. 

Legislative controls are generally applicable to the various forms of wastes and disposal routes. 

Will this allow syntheses to be automated It depends how difficult syntheses are (and will provide a way of quantifying this). It may be that the best possible synthesis is not required, provided that a good route is available, as assessed by total cost (including waste disposal and safety precautions), by time required, by certainty of success, by ease of using robots to follow the procedure, and so on. 

The fact that endrin is no longer produced or used in the United States greatly reduces the potential for human exposure. Future levels of endrin, endrin aldehyde, and endrin ketone in environmental media are expected to be low. The most significant route of exposure is most likely ingestion of imported foods contaminated with endrin however, there may also be some localized risks from exposures near waste disposal sites or from groundwater contaminated with endrin. 

Endrin has also been shown to be absorbed after ingestion by humans (Coble et al. 1967 Curley et al. 1970 Kintz et al. 1992 Rowley et al. 1987 Runhaar et al. 1985 Waller et al. 1992 Weeks 1967) however, no studies were located on the rate or extent of absorption that occurs in orally exposed humans or animals. Exposure to endrin through ingestion of contaminated drinking water is not expected to be an important source of concern because the compound has only rarely been detected in drinking water (Schafer et al. 1969 Wnuk et al. 1987). Since endrin is tightly bound to soil particles, ingestion of endrin-contaminated soil, particularly by children, may be an important route of exposure near hazardous waste disposal sites that contain endrin. 

Given the enormous number of toxicants, it is difficult to classify them chemically, either by function or by mode of action, since many of them would fall into several classes. Some are natural products, many are synthetic organic chemicals of use to society, while others are by-products of industrial processes and waste disposal. It is useful, however, to categorize them according to the expected routes of exposure or according to their uses. 

Exposure Assessment. In exposure assessment, the population potentially exposed to hazardous substances and the pathways and routes through which exposure could occur are specified, and the magnitude, duration, and timing of the doses people might receive are quantified. The approach to exposure assessment for hazardous waste disposal can range from very sophisticated and complex e.g., Wilson et al., 1994) to a multiplication of simple factors (e.g., Dornsife, 1995 EG G, 1982 EPA, 1989 Smith et al., 1980). Exposure assessment for waste disposal is itself a multi-step process, and is discussed below. 

In the case of a hazardous waste disposal site, the geo-hydrologic setting characteristics must now be carefully considered to assess the existence of subsurface exposure routes. Also, the potential for exposure from air emissions and surface runoff must be quantified where possible. Overall, the significant factors would include (1) evaluating the volatility of the wastes which could lead to short- and long-term exposure to air... 

The choice of recycling option depends primarily on the waste-disposal infrastructure already in place. The choice of recycling route will differ according to product group and region. The goal... 

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