Experimental Study On The Influence Factors Of Dioxin Adsorption By Activated Carbon

Incineration technique is widely used as an efficient method for municipal solid waste (MSW) treatment. However, the combustion of organic matter in MSW leads to toxic pollutant emissions such as polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), which is a risk to the environment as well as human health. Activated carbon (AC) has been long used in removal of PCDD/Fs from municipal solid waste incinerator (MSWI), and activated carbon injection (ACI) with dual bag filter (DBF) is a major PCDD/Fs control device in MSWI. This paper mainly focused on the dioxin adsorption behavior of four specific ACs in laboratory-scale fix-bed system and optimizing dioxin removal efficiency with ACI+DBF technology in pilot-scale system.To obtain the two aims, the physicochemical properties of the four ACs including BET-surface, pore-size distribution, iodine value, methylene blue value were examined before adsorption experiments.The results of adsorption experiment in laboratory-scale fix-bed system showed that the key factor of AC on the dioxin removal efficiency is mesopore volume rather than the total BET-surface and micropore volume. And surface area of mesopore (20-200A) is the critical factor affecting PCDD/Fs adsorption capacity. Generally, the increase of adsorption temperature and time would reduce the dioxin removal efficiency. And there was hardly any adsorptive selectivity for the17toxic dioxin homologs.To study the AC adsorption behavior for PCDD/Fs in real flue gas from MSWI,a pilot-scale system was equipped with ACI+DBF developed for the adsorption of PCDD/Fs from real incineration gas streams. Excellent dioxin removal efficiency was achieved and the efficiency increased with the increase of AC feeding rate. The toxic equivalent quantity (TEQ) of PCDD/Fs could be controlled under0.1ng I-TEQ/Nm3when the AC feeding rate increased to250mg/Nm3. The other results on the relevance between physicochemical properties of AC and dioxin removal efficiency were similar with to the laboratory-scale adsorption experiment. The surface area of mesopore (20-200A) and some existing macropore were the critical factors affecting PCDD/F adsorption capacity.