The Ministry of Industry and other nine ministries and commissions jointly issued the "on strengthening the prevention and control of dioxin pollution guidance", clear to the existing dioxin-generating sources to take proactive measures to prevent and control pollution, and the current focus is to focus on the prevention and control of waste incineration and other key industries dioxin pollution work. What is dioxin? What are the benefits of controlling dioxin pollution to people's lives?
Dioxins accumulate in the human body
Dioxins (Dioxins, abbreviated as DXN) is a class of polychlorinated tricyclic aromatic hydrocarbons collectively, there are 209 isomers. The U.S. Environmental Protection Agency has recognized 30 kinds of dioxin substances, 2,3,7,8-tetrachlorodibenzo-p-dioxin is the most toxic, in 1997 the International Agency for Research on Cancer (IARC) has been designated as a clear human carcinogen. Dioxin is one of the first persistent organic pollutants (POPs) to be controlled under the Stockholm Convention. Dioxin has the *** properties of POPs, i.e. fat solubility and chemical stability, and is difficult to degrade in the environment. Once it enters the environment or living organisms, it will accumulate. The half-life of dioxin in the human body is 7 years on average.
Waste incineration produces dioxins
Dioxin-like compounds are basically not naturally occurring, but it is not intentionally produced by mankind, it is a by-product of industrial processes (smelting, bleaching of pulp, and certain herbicides, pesticides, antiseptics, and paint additives can be produced in the process of industrial production). Ninety percent of dioxins in the atmospheric environment originate from the incineration of municipal and industrial wastes, and various wastes, especially medical wastes, are prone to produce dioxins during incomplete combustion at low temperatures. Therefore, the atmosphere of cities, industrial areas or areas closer to the source of pollution will contain higher concentrations of dioxin.
Dioxins have the greatest impact on the fetus
People exposed to high doses of dioxins can develop skin lesions such as chloracne (a form of occupational acne) and skin discoloration, as well as changes in liver function. Chronic exposure to dioxins can cause damage to the immune system, the developing nervous system, the endocrine system, and reproductive function. Because dioxins are ubiquitous, all human beings have some amount of dioxin accumulation within their bodies. It is currently believed that exposure in the normal environment is generally unlikely to affect human health, but because of the high potential toxicity of this class of compounds, measures must be taken to try to reduce dioxin levels in the environment.
The developing fetus is the most sensitive to dioxins. Newborns are more susceptible because of their rapidly developing organ systems. Some individuals may be exposed to high levels of dioxins through diet (e.g., high consumption of fish from certain contaminated areas) or occupation (e.g., workers in the paper industry, incineration plants, and hazardous waste sites), resulting in a much higher risk of illness than the general population.
General conditions for dioxin generation in waste incinerators are: unstable combustion, uneven combustion temperature in the furnace, combustion temperature below 850 ℃ or less. 3T technology is the incinerator after the section of the combustion chamber ( secondary combustion chamber ) flue gas temperature combustion to 850 ℃ ( Temperature ), to maintain this temperature of the flue gas stays a certain amount of time ( Time ), at the same time to make the oxygen and refuse The fuel is efficiently perturbed (Turbulent). These three control conditions are usually referred to as 3T. 3T conditions can be met in the incinerator before the generation of a large number of dioxin-like substances to destroy the decomposition, and ultimately greatly reduce the dioxin in the incinerator outlet flue gas content.
Currently, China has gradually promoted 3T technology to control the generation of dioxin in the incineration process, and the use of semi-dry purification method + activated carbon injection method + baghouse dust collector method of flue gas treatment, the purification effect is remarkable.
Recently, Changzhou and Tongji University, a result of the world's leading technology to completely solve the problem.