Polychlorinated biphenyls discharges

Polychlorinated biphenyls (PCBs) zero 0.0005 Skin changes thymus gland problems immune deficiencies reproductive or nervous system difficulties increased risk of cancer Runoff from landfils discharge of waste chemicals... 

There is a vast range of aqueous organic pollutants with a wide toxicity profile. Some, e.g. polychlorinated biphenyls, certain herbicides, fungicides and pesticides, and organo-mercury compounds, are persistent and may bioaccumulate in the food chain. Trace contaminants such as sodium chloride, iron and phenols (especially if chlorinated) may also impart a taste to water. Typical consent levels for industrial discharges are provided in Table 13.10. 

NPDES = National Pollutant Discharge Elimination System NTP = National Toxicology Program OSHA = Occupational Safety and Health Administration OW = Office of Water PCB = Polychlorinated Biphenyl RfD = Reference Dose STEL = Short-term Exposure Limit TLV = Threshold Limit Value TSCA = Toxic Substances Control Act TWA = Time Weighted Average WHO = World Health Organization... 

Polychlorinated biphenyls (PCBs) are a family of compounds, manufactured in the United States from 1930-1975, which were used in a number of discard applications and extensively as an electrical insulating fluid (see Chap. 1). Environmental concerns have led to strict controls on the use of PCBs and standards for cleanup of PCB discharges. One of the purposes of this section is to present information on the chemical and physical characteristics of these compounds. Based on this, the mechanisms of their movement in the surface/subsurface environment can be explained. 

Polychlorinated biphenyls (PCBs) were once used extensively to fill electrical equipment, such as transformers and relays, but they are now banned because they are toxic when discharged to the environment. The basic biphenyl C12H10 is two benzene rings connected by a single bridge. 

The IT Corporation thermal destruction unit is a mobile unit that uses infrared incineration technology. The main objective of this process is to transform the feedstock into another form (an ash acceptable for delisting) while assuring safe discharge of exhaust gas products to the environment. The unit is capable of on-site remediation of wastes and soils contaminated with polychlorinated biphenyls (PCBs) and other organics. This technology is based on a conveyor belt furnace process. 

Meanwhile, many other chemicals have enabled our society to accomplish great technical advances. For example, we have learned to recover fossil hydrocarbons from the earth and use these for heating, for transportation fuels, and for synthetic starting materials. Likewise, synthetic compounds like tetraethyllead, chlorinated solvents, freons, methyl /-butyl ether (MTBE), polychlorinated biphenyls (PCBs), and many others (see Chapter 2) have enabled us to develop products and perform industrial processes with greater efficiencies and safety. However, it has become quite apparent that even such contained applications always result in a certain level of discharge of these compounds to the environment. 

In 1997, the United Nations Environment Programme (UNEP) Governing Council decided that immediate international action should be taken to protect human health and the environment. International negotiations to reduce and eliminate the emission and discharges of an initial set of 12 POPs were initiated at the Stockholm Convention on POPs in May 2001. The 12 substances that were addressed at the Stockholm Convention were aldrin, endrin, dieldrin, dichlorodiphenyltrichoroethanes (DDTs), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), chlordane, toxaphene, heptachlor, hex-achlorobenzene (HCB) and mirex. Basic information and status of major organochlorine pesticides in China are summarized in Table 8.1. 

Figure 4.17 Correlation of Hudson River volumetric discharge at Waterford, New York, to enantiomer fractions (EFs) of dissolved (A) and particulate PCB 95 In the Hudson River Estuary. (Reproduced with permission from Environmental Science and Technology, Chiral Source Apportionment of Polychlorinated Biphenyls to the Hudson River Estuary Atmosphere and Food Web, by Brian j. Asher, Charles S. Wong and Lisa A. Rodenburg, 41(17), 6163-6169. Copyright (2007) American Chemical Society)...

Sediment concentration data of major groups of organic contaminants -aliphatic and aromatic hydrocarbons, chlorinated pesticides, phenols, polychlorinated biphenyls and -dibenzodioxins - are summarized in Table 2-5 (the book by Moore Ramamoorthy contains information on physicochemical properties, production, uses and discharges, and on toxicity). 

The evaluation of environmental presence of toxic compounds provides a basis to manage natural water resources in an effective and sustainable manner. Diverse groups of organic chlorinated compounds, eg, organochlorine (OC) pesticides, chlorophenols (CPs) and polychlorinated biphenyls (PCBs) are discharged and their presence and distribution in water environments need to be controlled by means of an environmental risk assessment. 

Relatively little research has focused on the destructive capabilities of corona discharge for organic or biochemicals. Polychlorinated biphenyls (PCBs) and other halogenated organics may be easily broken down into a mixture of harmless chemicals using superoxide (0 ) generated in solution [1]. 

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