Target pollutants

Another pathway by which targeted pollutants enter the wastewater stream is through the disposal of spent batch process solutions into the sewer system. Spent solutions consist of aqueous wastes and may contain accumulated solids as well. Spent solutions are typically bled at a controlled rate into the wastewater stream. Other sources of pollutants in wastewater streams include cleanup of spills and washdown of fugitive aerosols from spray operations. 

When the rates of sorption or desorption processes are known, environmental fate modeling can provide an educated estimate and prediction on the accessibility and bioavailability of a target pollutant to a specific transport mechanism in the environment. Hence, the present chapter is an attempt to assess fate (i.e., in terms of pollutant mobility using predictive sorption or desorption coefficients) as well as effects (i. e., in terms of bioavailability) of various pollutants and to correlate these observations for development of predictive relationships. 

Over the last decade, much interest has been generated in monitoring environmental problems and associated risks of wastes, in particular, wastewaters generated by the pulp and paper industries. A major goal is to reassess the target pollutant levels and consider the use of risk-based discharge permit values rather than the absolute endpoint values. This risk-based approach requires analytical tools that can quantify the ecotoxic characteristics of discharges rather than the absolute concentration of specihc pollutants or the values of lumped pollution parameters such as BOD, COD, and so on. 

There are important limitations in understanding the spatial and temporal trend of the pollutant levels of waterbirds, which is particularly true in China. Many studies that have been conducted in China have focused on water and sediment. There is limited information of pollutant levels in waterbirds available in China. In addition, a number of studies have investigated target pollutants with different tissue samples of different species. It has been determined that different tissue samples of species of birds can accumulate varying degrees of pollutants. It would be more instructive to compare tissue samples within species. Moreover, it is difficult to adequately compare current results with previous ones (i.e. 1940s-1970s) because of the advanced capability and improved sensitivity of instruments, and the application of different extraction methods and standards for quantification. 

Recent research has focused on the development of enzymatic processes for the treatment of wastewaters, solid wastes, hazardous wastes, and soils. The environmental applications may be classified according to their objectives. For example, some processes are specifically designed to accomplish the transformation of target pollutants in wastewater streams to reduce toxicity. Alternatively, the conversion of waste materials can sometimes be achieved in a manner that produces a product with commercial value. Some applications that have recently been identified will be outlined below. 

When a target pollutant compound is attacked by HO, three main mechanisms may be involved in the degradation of organics hydrogen abstraction, OH addition or substitution, and electron transfer. Hydrogen abstraction is generally the first step in many acid compounds [1,4] ... 

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