tailieunhanh - Phsicochemical Treatment of Hazardous Wastes - Chapter 10

Việc tiêu hủy chất thải hữu cơ độc hại tập trung là một vấn đề lớn mà đất nước đang phải đối mặt. Ví dụ, Hải quân Mỹ và quân đội tạo ra khoảng tấn / năm tập trung vật liệu hữu cơ độc hại. Bột giấy và ngành công nghiệp giấy tạo ra 2,8 triệu tấn bùn khô mỗi năm. Hiện nay, thiêu đốt và quá trình oxy hóa nước siêu tới hạn (SCWO) là hai lựa chọn chính để tiêu hủy hoàn toàn nước thải độc hại tập trung và bùn hữu cơ, tuy nhiên, quá trình. | 10__ Supercritical Water Oxidation Introduction The destruction of concentrated toxic and hazardous organic wastes is a major problem facing the nation. For example the . Navy and Army generate about 10 000 tons year of concentrated hazardous organic materials. The . pulp and paper industry generates million tons of dry sludge each year. Currently incineration and supercritical water oxidation SCWO are the two primary options for complete destruction of concentrated toxic wastewater and organic sludge however incineration process might cause air pollution if incomplete combustion occurs. SCWO process is one of the best physicochemical processes for destruction of concentrated toxic and hazardous organic wastes. Organic-laden wastes such as waste oil solvent cleaners paint sludge pulp sludge and municipal and refinery slurries can be treated economically with high destruction efficiencies due to the high content of thermal energy. After these wastes are treated residuals including gases liquids and solids are usually nontoxic. Remediation of contaminated soils is another application of the SCWO process. Bench-scale testing has shown that hazardous and toxic organics can be extracted from soil and simultaneously oxidized in an SCWO reactor. Soil slurries containing 1 to 20 of organic wastes can be continuously fed to an SCWO reactor system. The effluents are water CO2 and NO2 and the soil is sterilized and free of organics. Concentrated organic wastes and dilute aqueous waste frequently present at the same site can be blended to provide a feed with the appropriate heating value in a concentration range of 1 to 20 wt . Table summarizes historical aspects of SCWO research and development. Fundamental Theory Characteristics of Supercritical Water Water may exist in three phases solid liquid and gas however at elevated temperatures and pressures above its critical point 374 C and 221 atm 2004 by CRC .