Fundamental characteristics of input waste of small MSW incinerators in Korea

Waste incineration in a small incinerator is a simple and convenient way of treating waste discharged from small areas or from large facilities and buildings such as business centers, marketplaces, factories, and military units. Despite their ostensible advantages, however, many small incinerators frequently suffer from serious problems, e.g., unsystematic waste feeding, unstable combustion, deficient air pollution control devices, and consequently, environmental pollution. To obtain a better understanding of the characterization of wastes in small incinerators, we investigated a series of fundamental characteristics, i.e., physical composition, bulk density, proximate and ultimate analysis, potential energy content, and so on. The main waste components in small incinerators were identified as paper and plastic; the proportion of food waste was less than that in large incinerators. Especially, a low ratio of food waste had a strong influence on other waste characteristics, e.g., lower moisture content and bulk density, and higher potential energy. On the other hand, in contrast with that of HCl, there was no distinguishable linear relationship between Cl content in waste and PCDD/DF concentration in combustion gas.     

Mass Load-Based Pollution Management of the Han River and Its Tributaries, Korea

Spatio-temporal variations of biochemical oxygen demand (BOD) and total coliform (TC) in the Han River, Korea, were investigated in terms of concentration-based and mass loading-based approaches. Considering the river water quality criteria regulated by the Ministry of Environment in Korea, the tributaries linked to the mainstream of the Han River were found to be highly contaminated with respect to both BOD and TC and, in fact, most of the tributaries exceeded the maximum water quality criteria. To evaluate the pollution impact of tributaries on the mainstream, the monthly water quality monitoring data for six years (from 1995 to 2000) were collected from the Han River basin, and statistically analyzed using Pearson’s correlation coefficient. The results revealed that mass loading-based approach was superior to the concentration-based approach for effective Han River watershed management. Overall results supported that the mass loading-based approach associated with total maximum daily loads (TMDL) management would be a useful and suitable protocol in watershed management for improving the water quality of the Han River and protecting public health. Therefore, this study supporting TMDL management can be applicable to a wide array of contaminants and watershed settings in Korea.     

Response of microbial growth to orthophosphate and organic carbon influx in copper and plastic based plumbing water systems

Consequences of orthophosphate addition for corrosion control in water distribution pipes with respect to microbial growth were investigated using batch and dynamic tests. Batch tests showed that the release of copper in either low or high organic carbon content water was decreased by 69% and 56% with addition 206 microg PO(4)-P, respectively. Dosing of orthophosphate against corrosion did not increase microbial growth potential in the water and in the biofilm in both corroded and uncorroded systems receiving tap water with a low content of organic carbon and of biodegradable organic fraction. However, in tap water having a high concentration of organic carbon from acetate addition, orthophosphate addition promoted the growth of bacteria, allowed more bacteria to assemble on corroded and uncorroded surfaces, and increased the consumption of organic carbon. Orthophosphate consumption did not exceed 1% of the amount of easily biodegradable organic carbon required for microbial growth, and the orthophosphate demand for corrosion control greatly exceeded the nutritional requirement of microbial growth. The results of the dynamic tests demonstrated that there was a significant effect of interaction between biodegradable organic carbon and orthophosphate on biofilm growth, whereby the effect of orthophosphate flux on microbial growth was dependent on the levels of biodegradable organic carbon. Controlling an easily biodegradable organic carbon would be therefore necessary to minimize the microbial growth potential induced by orthophosphate-based anticorrosion treatment.     

Strategies for sustainable development of industrial park in Ulsan,South Korea—From spontaneous evolution to systematic expansion of industrial symbiosis

The Korea National Cleaner Production Center (KNCPC) affiliated to the Korea Institute of Industrial Technology (KITECH) has started a 15 year, 3-phase EIP master plan with the support of Ministry of Commerce, Industry, and Energy (MOCIE). A total of 6 industrial parks, including industrial parks in Ulsan city, known as the industrial capital of South Korea, are planning projects to find the feasibility of shifting existing industrial parks to eco-industrial parks. The basic survey shows that Ulsan industrial complex has been continuously evolving from conventional industrial complexes to eco-industrial parks by spontaneous industrial symbiosis. This paper describes the Korean national policies and the developmental activities of this vision to drive the global trend of innovation for converting the existing industrial parks to eco-industrial parks through inter-industry waste, energy, and material exchange in Ulsan Industrial complexes. In addition, the primary and supportive components of the Ulsan EIP pilot project, which will be implemented for 5 years is elaborated with its schedules and economic benefits.     

A combined approach of physicochemical and biological methods for the characterization of petroleum hydrocarbon-contaminated soil

Main physicochemical and microbiological parameters of collected petroleum-contaminated soils with different degrees of contamination from DaGang oil field (southeast of Tianjin, northeast China) were comparatively analyzed in order to assess the influence of petroleum contaminants on the physicochemical and microbiological properties of soil. An integration of microcalorimetric technique with urease enzyme analysis was used with the aim to assess a general status of soil metabolism and the potential availability of nitrogen nutrient in soils stressed by petroleum-derived contaminants. The total petroleum hydrocarbon (TPH) content of contaminated soils varied from 752.3 to 29,114 mg kg^?1. Although the studied physicochemical and biological parameters showed variations dependent on TPH content, the correlation matrix showed also highly significant correlation coefficients among parameters, suggesting their utility in describing a complex matrix such as soil even in the presence of a high level of contaminants. The microcalorimetric measures gave evidence of microbial adaptation under highest TPH concentration; this would help in assessing the potential of a polluted soil to promote self-degradation of oil-derived hydrocarbon under natural or assisted remediation. The results highlighted the importance of the application of combined approach in the study of those parameters driving the soil amelioration and bioremediation.     

A study on hexachromic ion selective electrode based on supported liquid membranes

An ion selective electrode (ISE) for determining Cr(VI) using supported liquid membranes (SLMs) containing trioctylphosphine oxide (TOPO) was investigated in this study. TOPO, as a carrier, had a high selectivity for Cr(VI) against interfering ions such as sulfate, nitrate, nitrite, and chloride. The composition of the SLM was optimized as 0.193 g TOPO/1 mL NPOE (o-nitrophenyl octyl ether)/0.5 g poly (vinyl chloride) for detection of Cr(VI). The Cr(VI) concentration was measured in the range of1 × 10^-3 to 1 × 10^-6 M with the SLM prepared in the study. It seemed that Cr(VI) was transported in the SLM as a triply charged ion indicated by the slope of the emf response. Selectivity coefficients and detection limits of Cr(VI) in the presence of interfering ions were determined experimentally using the fixed interference method.     

Impact of land-use types on nitrate concentration and δN in unconfined groundwater in rural areas of Korea

An understanding of the long-term changes in the nitrate contamination pattern of unconfined groundwater is critical to conservation of drinking water in rural areas supporting mixed land-use activities such as cropping, livestock farming, and residence. To examine the effect of different land-use activities on nitrate contamination, groundwater samples were collected monthly for 3 years (1997–1999) from 12 wells in rural areas with different land-use activities and analyzed for the concentrations and N isotopic ratios (δ¹⁵N) of nitrate. The characteristics of nitrate contamination clearly differed with land-use activities. The percentages of samples that had a nitrate concentration exceeding the national standard for drinking water (10 mg N L⁻¹) were 0, 23, 43, and 67% for the uncontaminated natural area, cropping area, cropping-livestock farming complex area, and residential area, respectively. The range of δ¹⁵N values was between +1.4 and +4.5‰ for groundwater nitrate from the uncontaminated natural area. In the cropping area, the δ¹⁵N values were slightly different with the type of fertilizer applied to fields in the vicinity of the well, and the values ranged between +8.7 and +14.4‰ for the compost-applied area and between +4.5 and +8.5‰ for the area where urea was applied with compost. The δ¹⁵N values of the cropping-livestock farming complex area ranged from +1.0 to +17.7‰, probably resulting from mixed contamination sources (inorganic fertilizer and livestock manure). The well located closest to the livestock feedlot had relatively higher δ¹⁵N values, with a range between +8.7 and +17.6‰. In the residential area, a higher δ¹⁵N (most frequently above +10‰) of nitrate suggested that the major source of contamination was effluent from leaky septic tanks. Our data showed that unconfined groundwater is susceptible to land-use activities above the aquifers, and the impacts of the activities could be more precisely inferred from long-term data on the concentration and δ¹⁵N of nitrate. By determining the impacts, more effective (specific to contamination sources) measures for preventing groundwater quality could be implemented.     

Self‐efficacy changes in groups: effects of diversity,leadership, and group climate

Self‐efficacy belief is a significant predictor of behavioral choices in terms of goal setting, the amount of effort devoted to a particular task, and actual performance. This study conceives of formation and change of self‐efficacy as a social and context‐dependent process. We hypothesized that different group factors (discretionary and ambient group stimuli) influence changes in members' self‐efficacy through differing routes (individual‐level and cross‐level processes). We tested our hypotheses using data from individuals in 169 training groups who attended a 5‐day workshop designed to increase participants' job‐search skills and efficacy. Specifically, we examined the degree of change in participants' job‐search efficacy before and after the workshop. The results showed that (a) membership diversity in education was positively related to increases in job‐search efficacy, (b) supportive leadership contributed to job‐search efficacy at the individual level of analysis with no cross‐level effects, and (c) open group climate contributed to job‐search efficacy through both individual‐level and cross‐level processes. Limitations and directions for future research are discussed. Copyright © 2003 John Wiley & Sons, Ltd.     

GIS BASED LONG TERM HYDROLOGIC IMPACT EVALUATION FOR WATERSHED URBANIZATION1

ABSTRACT: To adequately manage impacts of ongoing or future land use changes in a watershed, the magnitude of their hydrologic impacts needs to be assessed. A grid based daily streamflow model was calibrated with two years of observed streamflow data, using time periods when land use data are available and verified by comparison of model predictions with observed streamflow data. Streamflow data were separated into direct runoff and baseflow to estimate the impacts of urbanization on each hydrologic component. Analysis of the ratio between direct runoff and total runoff from 30 years of simulation results and the change in these ratios with urbanization shows that estimated annual direct runoff increased from 49.2 percent (1973) to 63.1 percent (1984) and 65.0 percent (1991), indicating the effects of urbanization are greater on direct runoff than on total runoff. The direct runoff ratio also varies with annual rainfall, with dry year ratios larger than those for wet years. This suggests that the impact of urbanization on areas that are sensitive to runoff ratios, such as stream ecosystems, might be more serious during drier years than in wetter years in terms of water quality and water yield. This indicates that sustainable base‐flow is important to maintaining sound stream ecosystems.     

Hydrochemistry of urban groundwater, Seoul, Korea: the impact of subway tunnels on groundwater quality

Hydrogeologic and hydrochemical data for subway tunnel seepage waters in Seoul (Republic of Korea) were examined to understand the effect of underground tunnels on the degradation of urban groundwater. A very large quantity of groundwater (up to 63 million m³ year^− 1) is discharged into subway tunnels with a total length of 287 km, resulting in a significant drop of the local groundwater table and the abandonment of groundwater wells. For the tunnel seepage water samples (n = 72) collected from 43 subway stations, at least one parameter among pathogenic microbes (total coliform, heterotrophic bacteria), dissolved Mn and Fe, NH₄⁺, NO₃⁻, turbidity, and color exceeded the Korean Drinking Water Standards. Locally, tunnel seepage water was enriched in dissolved Mn (avg. 0.70 mg L^− 1, max. 5.58 mg L^− 1), in addition to dissolved Fe, NH₄⁺, and pathogenic microbes, likely due to significant inflow of sewage water from broken or leaking sewer pipes.Geochemical modeling of redox reactions was conducted to simulate the characteristic hydrochemistry of subway tunnel seepage. The results show that variations in the reducing conditions occur in urban groundwater, dependent upon the amount of organic matter-rich municipal sewage contaminating the aquifer. The organic matter facilitates the reduction and dissolution of Mn- and Fe-bearing solids in aquifers and/or tunnel construction materials, resulting in the successive increase of dissolved Mn and Fe. The present study clearly demonstrates that locally significant deterioration of urban groundwater is caused by a series of interlinked hydrogeologic and hydrochemical changes induced by underground tunnels.