Open burning of solid wastes, a potential nonpoint emission source, has recently become a topic of interests, particularly in the metropolitan area of Seoul, Korea. To estimate the effects of irregular open burning on local air quality, we evaluated the emission levels of harmful substances from test combustion of individual types of domestic municipal solid waste (MSW), including paper, wood, and plastics. The emission factors of PM 10 , PM 2.5 , PAHs, and heavy metals obtained from laboratory tests differed depending on the combustion material. A brief survey of residents and local government officials showed that more than 10.6% of homes in the metropolitan area have eliminated waste by irregular burning. Based on the public survey in the test area, the average annual emissions of hazardous materials from frequent open burning was estimated to be 71 tons for PM 10 , 46.6 tons for PM 2.5 , 914 kg for heavy metals, and 67 kg for PAHs. Open burning creates nearly 0.44% of regional air pollution from PM 10 .

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The particle velocity model developed in this study described the dynamic motion of fine dust particles along the magnetized mesh wires in a low Stokes regime. The numerically evaluated velocity contour of the particles modeled the critical path lines indicating the threshold positions for magnetic collection. The velocity contour was determined using the parameters such as particle size, magnetic intensity, flow velocity, and mesh configuration including wire thickness and packing density. Particle size was one of the most significant parameters to determine the magnetic collection. The theoretical estimation matched well with the lab experiments, but the discrepancy increased for large particles with a fine filter. In consequence, application of magnetized mesh filters could contribute to the collection of the ferromagnetic dust or aerosols to a certain extent without any additional power or pressure resistance.

The flue gas dispersion from the stack of a power station was investigated prior to addition of a high efficiency heat recovery facility. Decrease of the flue gas temperature from 115°C to 40°C by heat recovery could influence the local humidity and thermal NO x level. It might also result in the formation of a white large plume due to the early saturation of vapor around the stack, and deteriorate dispersion of thermal NO x . Numerical simulation revealed that the area influenced by flue gas has been enlarged, particularly in winter. The volume of visible plume indicating RH 1.0 increased to 120 m high and 80 m wide for the flue gas at 40°C, while a smaller plume was formed that was 85 m high and 50 m wide for that at 115°C. The humid air of the flue gas extended nearly 160 m further along the ground. The distance for the maximum NO 2 concentration on the ground increased by 80 m and 50 m for 1 m/s wind and 3 m/s, respectively. The area influenced at the ground level expanded more than 250 m at 1 m/s wind after heat recovery. In particular, lowering the temperature of flue gas may affect the local environment more significantly in unusual cases including temperature inversions.

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