Food waste is both an industrial and residential source of pollution, and there has been a great need for food waste reduction. As a preliminary step in this study, waste reduction is quantitatively modeled. This study presents two models based on kinetics: a simple kinetic model and a mass transport-shrinking model. In the simple kinetic model, the smaller is the reaction rate constant ratio k1 , the lower the rate of conversion from the raw material to intermediate products. Accordingly, the total elapsed reaction time becomes shorter. In the mass transport-shrinking model, the smaller is the microbial decomposition resistance versus the liquid mass transfer resistance, the greater is the reduction rate of the radius of spherical waste particles. Results showed that the computed reduction of waste mass in the second model agreed reasonably with that obtained from a few experimantal trials of biodegradation, in which the microbial effect appeared to dominate. All calculations were performed using MATLAB 2020 on PC.
This study intended to propose an improvement plan to improve user satisfaction by establishing a park and green space masterplan by comparing its current status and surveying the residents’ perception of green park services in two regions. The study results showed that the residents are aware of the physical and qualitative aspects of the green park environment. In addition, the quality level of the green park that people may actually use in everyday life was considered a factor for evaluation of satisfaction. In addition, it was found that the residents, who are actual users of the green park services, evaluated the satisfaction of use considering the qualitative characteristics of the green park, such as ‘quality of green park’ and ‘availability of green park.’ As a result, efforts are required to create and improve the quality of green parks efficiently based on establishing qualitative indicators, a survey of residents’ perception, and quantitative analysis to develop policy directions and guidelines of the park and green space masterplan.
This study investigated the biomass content of fluff type SRF(Solid refuse fuel) operated in B city according to the physical composition. As a result of analyzing the physical composition of SRF, it was investigated that papers 25.2%, fiber 15.1%, vinyl‧plastics 42.6%, woods 9.4%, rubbers 1.5%, diapers 3.2% and incombustibles 3.0%. The average of ash and combustible content of SRF was 10.5% and 89.5%, and the higher the proportion of paper and wood, the lower proportion of ash. In addition, the biomass of SRF is 24.9%~58.0%, with an average of 42.6%.
This research investigated the characteristics of fine particle concentration and ionic elements of PM2.5 during sea breeze occurrences during summertime in Busan. The PM10 and PM2.5 concentrations of summertime sea breeze occurrence days in Busan were 46.5 ㎍/㎥ and 34.9 ㎍/㎥, respectively. The PM10 and PM2.5 concentrations of summertime non-sea breeze occurrence days in Busan were 25.3 ㎍/㎥ and 14.3 ㎍/㎥, respectively. The PM2.5/PM10 ratios of sea breeze occurrence days and non-sea breeze occurrence days were 0.74 and 0.55, respectively. The SO4 2-, NH4 +, and NO3 - concentrations in PM2.5 of sea breeze occurrence days were 9.20 ㎍/㎥, 4.26 ㎍/㎥, and 3.18 ㎍/㎥ respectively. The sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) of sea breeze occurrence days were 0.33 and 0.05, respectively. These results indicated that understanding the fine particle concentration and ionic elements of PM2.5 during sea breeze summertime conditions can provide insights useful for establishing a control strategy of urban air quality.
This research investigated the characteristics of fine particles during cold front passage in Busan, on March 19, 2020. The cold front speed was 17.4 m/s (about 63k km/hr), moving from the northwest to the southeast, and with a width of about 64 km. The backward trajectory analysis showed that a southern sea air parcel flowed into Busan before the cold front passage, carrying continental materials from China transported into Busan after cold front passage. The PM10 concentration in Busan showed a rapid increase after passing through the cold front, with PM2.5 showing a high concentration during cold front passage. The PM2.5/PM10 ratio was 0.10 - 0.30. When the cold front passed, SO4 2-, NO3 -, Ca2+, NH4 +, Na+, and K+ in PM2.5 showed a rapid increase, with SO4 2- showing the most significant increase. These results indicated that understanding the characteristics of fine particles during cold front passage in Busan could provide insight into establishing a strategy to control urban air quality.
To evaluate the geochemical characteristics and assess the pollution in surface sediments of the Nakdong River estuary, two sites adjacent to the estuary bank (Hh1 and Hh2) and one site at the upper part of the estuary bank (Hh3) were investigated. The surface sediments were analyzed for their contents of metals (Cu, Pb, Ni, Cr, Zn, and Al), organic matter (IL, COD, TOC, and TN), and grain size from 2018 to 2020. As a result of the pollution assessment, there was little anthropogenic contamination by most of the metals. The surface sediments in Hh2 had comparatively abundant silt and clay, whereas the other sites were mainly composed of sand. The organic index and contents of organic matter were highest at Hh2. Multivariate statistical analyses (cluster analysis and Pearson correlation analysis) showed that the contents of organic matter and pollution were associated with fine sediment. These results suggest that the geochemical characteristics were changed by the estuary bank built in the research area and that the increase in fine sediment attributable to the low-energy environment resulted in an increase in organic matter pollution.
V2O5-TiO2 catalysts were prepared by various methods. V2O5-TiO2 were prepared by sol-gel method with different drying conditions (aerogel and xerogel), and V2O5 supported on TiO2 obtained by sol-gel method with precipitation-deposition method and impregnation method. The performance of the V2O5-TiO2 catalysts was investigated for the selective oxidation of hydrogen sulfide in the stream containing both ammonia and excess water. All the catalysts showed good dispersion of vanadium and they had high H2S conversion with no or little production of sulfur dioxide. The V2O5-TiO2 aerogel catalyst prepared by sol-gel method with drying under super critical condition had the highest surface area which led to better catalytic activity compared to those by other synthesis methods.