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Phsicochemical Treatment of Hazardous Wastes - Chapter 2

Như là một kết quả của quá trình đô thị hóa trên toàn thế giới và công nghiệp hóa, nhiều hợp chất hữu cơ độc hại và nguy hiểm đã tìm thấy con đường của họ vào vùng nước bề mặt và mặt đất, cả hai đều là nguồn gốc của nước uống. Việc xử lý hơn 40.000 hóa chất hữu cơ được sử dụng bởi các ngành công nghiệp khác nhau tại Hoa Kỳ đã dẫn đến một loạt các vấn đề chất thải nguy hại. Lượng nước thải công nghiệp có chứa các chất gây ô nhiễm ngoan. | 2 Environmental Hazardous Wastes 2.1 Introduction As a result of worldwide urbanization and industrialization numerous toxic and hazardous organic compounds have found their way into surface and ground waters both of which are the source of drinking water. The disposal of over 40 000 organic chemicals used by various industries in the United States has resulted in a broad range of hazardous waste problems. The amount of industrial wastewater containing these recalcitrant pollutants is increasing significantly. Many of these chemicals are resistant to degradation and pose a potential health threat to the human population. In addition many hazardous waste materials are recalcitrant normally nonbiodegrad-able and even toxic to microorganisms therefore physicochemical treatment techniques are better alternatives than biological treatment. Since 1970 one of the most widespread industrial practices has been the halogenation of organics which produces organic solvents pesticides chlorofluorocarbons CFCs and polychlorinated biphenyls PCBs . The halogenation of hydrocarbons yields compounds of lower flammability higher density higher viscosity and improved solvent properties compared to nonhalogenated solvents. For example 46.5 of chlorine gas used in the United States was for the production of chlorinated organic compounds. Classified as derivatives of aliphatic hydrocarbons halogenated solvents have been used extensively in a number of industrial processes and over 400 000 tons of halogenated solvents are used annually for metal cleaning. Due to their higher density high water solubility and low degradability chlorinated solvents are extremely mobile in groundwater. Chlorinated solvents are commonly used in the manufacturing of pesticides. Carbon tetrachloride is a commercial product widely used in the United States for dry cleaning metal degreasing and fire extinguishers. It is also used for the production of CFCs and grain fumigation. Methylene chloride is commonly used