• Journal of Environmental Impact Assessment
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• v.25 no.6
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• pp.466-476
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• 2016

Dredging is inevitably necessary for the management of water infrastructure such as waterways and polluted bottom sediment. Dredged material management options may be offshore dumping, wetland creation, beach nourishment and various other engineering uses depending on the given circumstances at the time of dredging. Among those options, wetland creation and beach nourishment are the preferred ones in Korea considering significant loss of wetland and beach erosion due to various development projects along the coastal region. In order to use dredged material beneficially, however, dredged material needs to be assessed its suitability with respect to its engineering purpose and environmental criteria. In this paper, we demonstrate that environmental risk of dredged material to be introduced into the marine environment can be easily assessed using biomarkers with relative low cost. Biomarkers can also compliment pollutant contents analysis that may not be specific to their impact on biological response. Biomarker information may be used to assist decision making process in selecting suitable treatment or beneficial use options for dredged materials.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.1
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• pp.27-36
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• 2011

Squid by-product like viscera has just been recognized as one of the serious pollutants on the surrounding marine environment in Ulleung island of Korea. The effect as a marine pollutant, however, has not been examined and evaluated properly. It was carried out the comprehensive examination of the marine pollution by disposing squid by-products. The sediments and water qualities were investigated in several positions, including the dumping position around Ulleung island. It is also estimated a spreading of by-product in terms of estimating the sinking speed and evaluating the attracting characteristics as a feed. As a result, There were no significant pollutions of the sediment and water quality. The spreading of by-product by the local current was 2-2.5 times of the depth, and it will become longer in spring tide. It was confirmed that the squid by-product has attracting ability for local fish by acoustical survey. Furthermore, it can be useful for the local fish species as feeds.

• Journal of Korean Society on Water Environment
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• v.26 no.2
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• pp.225-230
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• 2010

Dumping of waste sludge to ocean will be prohibited in Jananuary, 2012. Thus, various methods of sludge recycling are intensively studied. To present new way of sewage sludge recycling method, feasibility of making porous biological support media was investigated. Porous biological support media was made of sludge cake from sewage treatment plant and loess. They were mixed in varying ratio and burnt in high temperature to ensure sufficient mechanical strength. It was evaluated that about 67% of sewage sludge were ignitible. The ignitible portion play an important role in making pore in biomedia during ignition process. It was evaluated that optimum mixing ratio of loess to sludge cake was 25% in respect of compressive strength. In results of observation using scanning electron microscope (SEM), inner structure of biomedia become simple when the contents of loess are increased.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.1
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• pp.1-6
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• 2010

Paper industry in Korea produces 14 million tons of paper and 1.3 million tons of sludge per year. Most of them has been treated by incineration, landfilling or ocean dumping. The sludge recycling to minimize the impact on the environment, so its importance is highlighted. In this study, in order to develop a new way of recycling the sludge, it was calcined and the recycled ash was tried to use as papermaking filler. Concerning the yield of calcium carbonate and the brightness and the rheology of the recycled calcination sludge, the optimum calcination conditions were found to be $600^{\circ}C$ and 12 hours. The sludge ash itself was not suitable for papermaking due to its color and low brightness. Thus the ash from the sludge was first mixed with a commercial filler and then utilized for papermaking. The effect of the increased hardness after high temperature treatment on wire abrasion was confirmed.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.2
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• pp.182-189
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• 2012

Co-combustion of sludge with coal is proposed as an alternative option for sludge disposal instead of ocean dumping. Because the combustion of sludge can cause emissions of various air pollutants, it is important to understand the characteristics of sludge combustion flue gases. Especially, very few studies are found to investigate mercury emissions from the co-combustion of sludge with coal. In this study, coal and sludge samples were prepared with different mixing ratios. These samples were combusted in a bench-scale combustor, and their flue gases were analyzed. Due to higher mercury content in the sludge sample, higher mercury emissions were found with an increase in a ratio of sludge to coal. Compared to the combustion flue gas of the coal sample, higher levels of mercury oxidation were found in the combustion flue gas of the samples including sludge.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_2
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• pp.73-77
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• 2001

The disposal of sewage sludge using landfills and ocean dumping is no longer a viable option due to land scarcity and increasingly stringent environmental control regulations. As such, various efforts have been made to develop new sewage sludge recycling technologies. This work investigates the fundamental physical and chemical characteristics of rural type sewage sludge from Chungnam province in South Korea. The average moisture content, ignition loss, elementary analysis, and average heating value of the sewage sludge samples were examined. The average moisture content of the dewatered sludge was about 80%, while the organic matter was about 50% of the total solid sludge weight. The average heating value of a sewage sludge and petroleum coke waste mixture(1:1 weight ratio) was about 5,000 ㎉/kg, thereby indicating a high potential for energy recycling.

• Journal of Korean Society on Water Environment
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• v.30 no.5
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• pp.559-567
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• 2014

Since the ocean dumping of organic wastes is prohibited under the London Convention, the need for land treatment of food waste leachate (FWL) has significantly been growing in recent years. This study was conducted to use thermal solubilization to turn FWL into a form that can easily be degraded during the anaerobic digestion process, thereby reducing the percentage of solids and increasing the production of methane. To derive the optimal operating conditions of thermal solubilization, a laboratory-scale reactor was built and operated. The optimal reaction temperature and time turned out to be $190^{\circ}C$ and 90 min, respectively. The BMP test showed a methane production of 465 mL $CH_4/g$ $COD_{Cr}$ and a biodegradation rate of 90.1%. The production of methane rose by about 15%, compared with no the application of thermal solubilization. To reduce the solid content of FWL and improve the methane production, therefore, it may be helpful to apply thermal solubilization to pre-treatment facilities for anaerobic digestion.

• Journal of Soil and Groundwater Environment
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• v.20 no.3
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• pp.1-6
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• 2015

The rapid industrial development is facing problem due to energy depletion in Korea. So that, it can be necessary to develop alternative energy sources. Alternative energy like biofuels can be produced by using waste fuel, which is ecofriendly. As we know, the organic waste was banned to dump in landfill and ocean dumping. The most practicable method usually used to reduce organic waste is getting feedstuff or composting, considering the discharge characteristics of agricultural by-products waste treatment were selected. In this study, bio-coal was made using agriculture by product. Biocoal was prepared by adding 50 g of uniformly mixture into reactor and was carbonized at low temperatures 210, 220, and 230℃. The time of reaction was 1, 2 and 3 hours. Bio-coal approximately was similar to the standard of solid fuels. Other characteristics of fuel were also studied. The experiments which were analyzed were moisture content and calorific value, ash, chlorine, sulfur and heavy metals analysis as mercury, cadmium, lead, arsenic, and chromium. As a result, bio-coal 220℃, 2 hours was the optimal conditions while heating.

• Clean Technology
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• v.8 no.2
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• pp.67-76
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• 2002

Dewatered sludge of 400,000t/y from water treatment plants in Korea is being disposed through landfill and ocean dumping. However, the disposal is posing more and more serious environmental problems at the same time not only because of landfill site shortage in municipal suburbs, but because of the concern it will contaminate the oceans. In this study, the research on utilizing the sludge dried by flash dryer as covering soil in the landfill sites was carried out to solve these problems on environmental affinity. Both dewatered and dried sludge were exposed to the natural condition and observed according to the atmospheric changes. An experiment of soil engineering characteristics of the dried sludge and tests on mixed sludge(silty sandy soil : dried sludge = 10:90 ~ 30:70) such as particle size distribution, liquid and plastic limit, moisture content, specific gravity and compaction test were carried out. According to the compaction test, the compaction was confirmed as the optimum water content ratio was observed in the condition of SM-silty sand of particle size distribution, NP of liquid and plastic limit, 101.4% of moisture content, 2.04~2.12 of specific gravity. The results showed that dried sludges mixed with at least 30% of natural soil could be used as daily covering soil in the landfill sites.

• Journal of Korean Society on Water Environment
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• v.31 no.5
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• pp.476-481
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• 2015

Water permeable block was manufactured using waste sewage sludge, loess and clay for the purpose of recycling waste sludge due to the prohibition of waste sludge ocean dumping. Experiments for determining optimum mixing ratio was conducted by changing sludge content in water permeable block as 5~20%. In respect of compressive strength, $1,600N/cm^2$ ($163.3kg/cm^2$) was obtained when the mixing ratio of sludge : loess : clay were maintained by 5% : 65% : 30%, 10% : 65% : 25% and 15% : 65% : 20%, respectively. These mean that relatively high compressive strength can be obtained when the sludge content is maintained 5, 10, 15% at the 65% of loess content. In terms of water permeability and absorption rate, the higher values can be obtained as the sludge content increases. The optimum mixing ratio of sludge : loess : clay came out to be 15% : 65% : 20% when water permeability, absorption and strength were considered altogether, which matches the result observed by an electron microscope. The heavy metal leaching test result of the prepared permeable block appeared to satisfy the environmental standard in the content of Cd, Cu, Pb and As.