Emission Characteristics Of Particulate Matter And Health Risk Assessment From Carbon Anode Industry In Zhengzhou

In order to perfect the localized source profiles and emission factors of emission source pollutants in Zhengzhou,three typical prebaked anode plants were selected for sampling in this study.Using the dilution channel method,92 particulate matter samples were collected from the stack gas of the prebaked anode plant,and the source component spectrum of the particulate matter emitted from the calcining and baking process in the prebaked anode industry was established.The emission factors and annual emissions of the particulate matter and its chemical components were calculated.This research discussed the differences between source profiles through coefficient of difference,and provides some characteristic ratios that could be used as source identification.Toxicity of particulate phase polycyclic aromatic hydrocarbons?PAHs?was evaluated according to Toxic Equivalent Quantity?TEQ?and Ba P equivalent carcinogenicity?Ba PE?.Meanwhile,72 samples of volatile organic compounds?VOCs?were collected in different functional areas of the plant used the US Environmental Protection Agency's?EPA?health risk assessment model,the cancer and non-cancer risks of 104 VOCs in the plant area were evaluated.The results showed that the calcining emissions of PM₁₀ and PM_2.5 in the prebaked anode industry ranged from 0.5–8.3 mg/m³ and 0.4–4.8 mg/m³,respectively,and the baking was 0.6–5.0 mg/m³ and 0.5–3.0 mg/m³,respectively.The range of PM_2.5/PM₁₀ was 56–88%,indicated that fine PM was dominated.The mass proportions of water-soluble ions,inorganic elements,organic carbon?OC?and elemental carbon?EC?in the PM was 37–42%,16–20%,11–17%,and 9.2–14%,respectively,among which calcining was mainly EC?Ca²⁺?OC?SO₄^2–?Na⁺,and baking was mainly OC?EC?Na⁺?SO₄^2–?NH₄⁺.The results of the divergence coefficient showed that there was a certain difference in the source profiles between the calcining and baking particles at the same particle size,and there was no difference between the different particle sizes with the same process.The anion/cation ratio results showed that the PM emitted by the calcining and baking were alkaline.The ratio of OC/EC indicated that the OC in the calcining PM was mainly emitted once,and the OC emitted by baking was mainly formed in the secondary.The composition and emission factors of particulate phase PAHs from calcining and baking were analyzed and calculated.The combustion derived PAHs accounted for 57.1–76.1%,indicated that the particulate phase PAHs in this study mainly came from the cracking of organics at high temperatures.The five-ring and four-ring PAHs were the main components of calcining,and the characteristic PAHs were Bk F,Flu,and Ace.The five-ring and three-ring PAHs were the main components of baking,and the characteristic PAHs were Ace,B[b,k]F,and Bghi P.The emission factors of the particulate phase PAHs of the calcining PM₁₀ and PM_2.5 were 181±52.8 mg/t and112±99.6 mg/t,respectively,and the banking were 992±855 mg/t and 771±1095mg/t,respectively.It was estimated that in 2019,the PAHs of PM₁₀ and PM_2.5 emitted from calcining in prebaked anode industry in Zhengzhou emitted 470.6 kg and 291.2kg,respectively,and baking emitted 2579.2 kg and 2004.6 kg,respectively.The particulate phase PAHs emissions in 2019 decreased by 21.2%compared to 2018.The TEQ results showed that the toxicity of baking PM was 4–5 times higher than that of calcining,and the toxicity of PM_2.5 was 19.6–33.1%higher than that of PM₁₀.The cancer risk?CR?of VOCs in the production area wsa 3.5×10^–5–2.8×10^–3,the management area was 2.0×10^–5–9.4×10^–5,which was higher than the maximum acceptable level recommended by the EPA(10^–6).The production area VOCs non-carcinogenic risk hazard index?HI?was 3.2–104,and the management area was0.43–3.8.It can be seen that there were serious cancer and non-cancer risks in the prebaked anode plant.