RESUMO
The characteristics of the VOCs species in foundry industries based on the production processes were analyzed through gas chromatography-mass spectrometry (GC-MS) after sampling the emissions of VOCs in 9 typical foundry enterprises using air packages and absorption tubes. The source profiles of the VOCs species in foundry industries based on production processes were established for the first time in China. In addition, the emission characteristics of VOCs and the contribution of VOCs emitted by various production processes to ozone generation were also studied. The results showed that the characteristic components of the VOCs in foundry industries were predominantly aromatic hydrocarbons, halogenated hydrocarbons, and oxygenated hydrocarbons. The average concentrations were 50.9%, 20.8%, and 12.6%, respectively. In general, aromatic hydrocarbons, such as toluene, benzene, and m/p-xylene; halogenated hydrocarbons, such as trichloroethylene and dichloromethane; oxygenated hydrocarbons, such as acetone, ethyl acetate, cyclopentanone, and some alkanes, were the primary VOCs species of the foundry industries. The emission characteristics of different production processes were related to the solvents and surface treating agents used by each process. The results also demonstrated that painting was the largest contributor of VOCs concentrations among all the production processes, followed by the modeling procedure and the silica sol and pouring processes. The OFP values for the different production processes ranged from 0.29-96.09 mg·m-3. Painting was the largest contributor to OFP, followed by the modeling procedure and the melting and pouring processes. Aromatic hydrocarbons and oxygenated hydrocarbons were the dominant contributors to OFP, and 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, toluene, and m/p-xylene were the main active components in the foundry industry, with a total contribution to the ozone generation potential of nearly 60%. It is suggested that the painting process should be prioritized regarding control measures to reduce its emissions and impact, while the waste gas from the modeling procedure and the melting and pouring processes should be collected efficiently and treated properly before being discharged to the environment.
RESUMO
120 main industrial installations were screened based on the emissions inventory of 2016 in Cangzhou City, and the air pollution effect of PM2.5, PM10, SO2, NO2, sulfates, nitrates, and secondary organic aerosol (SOA) was simulated for 2017 autumn-winter season for different levels of pollution using the CALPUFF model after code recompilation. The results showed that the ratios of the modelled and measured concentrations of PM2.5, PM10, SO2, and NO2 were 3.3%, 5.7%, 5.6%, and 2.9%, respectively. The areas most affected by pollution from primary PM10 were the southwest and southeast part of Cangzhou, while sulfate, nitrate, and SOA pollution mainly affected the southeast part. The proportion of SOA in the PM2.5 was around 27.3%, and rose to 29.0% during heavily polluted periods. The aerosols of alkenes, tolune, xylene, and PAH in PM2.5 accouted for 12.1%, 6.0%, 7.0%, and 2.2% of the total aerosols respectively. The result of the simulation of individual enterprises showed that their total contribution to PM2.5 during heavily polluted periods was 3.02 µg·m-3, accounting for 50% of the requirements in the "Three-year Plan" for Cangzhou City (6.00 µg·m-3). The top 5 contributors were 1 Petrochemical industry in Cangzhou (0.41 µg·m-3), 2 Carbon Co. Ltd. (0.29 µg·m-3), 3 Petrochemical industry in Juhai (0.26 µg·m-3), 4 Fertilizer Company (0.23 µg·m-3), 5 Dahua Co. Ltd. (0.19 µg·m-3). These industrial installations were mainly located in Xinhua District, Cangxian, and Bohai New District. This research can provide a scientific ground for production restrictions and limitations and emissions reduction of each industry during heavily polluted periods.
