Study On PCDD/Fs Emission Characteristics And BAT/BEP Of Hazardous Waste Incinerators

With the rapid development of China’s industry, the generation of hazardous and medical waste has increased annually. However incineration of these wastes produces dioxins and other toxic substances inevitably. In addition, our country’s survey of existing incineration facilities is unclear and dioxin emissions from incineration facilities also difficult to calculate. All these status bring great challenges and difficulties to carry out dioxin emission reduction work for our country. Based on the above background, this paper carried out a study on PCDD/Fs emission characteristics and BAT/BEP of hazardous waste incinerators (HWIs) and medical waste incinerators (MWIs), expecting to provide help for the technique optimization and pollutants reduction of hazardous and medical waste incineration industry in our country.Through online inquiry, field research and other methods, this paper investigated the distribution, disposal scale, air pollution control system and dioxin emission levels of our country’s HWIs and MWIs. Besides, a systematic and classified analysis on these dioxin emission levels was also conducted. The results show that the disposal of hazardous waste incineration should use rotary kiln incinerator. However, the disposal capacity, production cost, and dioxin emissions should be carefully considered when pyrolysis furnace or rotary kiln was used as to disposal medical waste. The dioxin emissions success rate of HWIs and MWIs with a capacity between10-20t/d was poorrer compared to other incinerators.In order to fill the research gap in our country, this paper studied the similarities and differences of dioxin emission characteristics during normal, start-up and shut-down operating conditions in our country’s typical HWIs and MWIs, which focus on the reason for sharp increase of dioxin concentrations and impact on the subsequent conditions. The contribution rates to the total dioxin emissions of different operation conditions have also been estimated. The results indicate that dioxin emissions contribution rate during start-up operation condition in HWI, start-up and shut-down three times a year, is about27.7%of total dioxin emissions and the shut-down’s is4.7%. While the contribution rate of start-up in MWI, start-up and shut-down daily, is higher about56.7%and the shut-down’s is27.4%. The memory effect of dioxin emissions during start-up lasted for a long time and became weaker with time gradually, which was mainly due to the gas phase dioxins. Besides, the correlation coefficient between dioxins and PCBs, as the important precursor of dioxins, during start-up and shut-down operating conditions reached up to0.97and abnormal PCBs emissions would also affect the subsequent conditions.Combining the above results, this paper also did some BAT/BEP researches on the technique optimization and pollutants reduction in our country’s waste incineration industry from the point of before-combustion, in-combustion process, after-combustion and environment management, forming some preliminary technical guidances and suggestions.