• Journal of the Korea Organic Resources Recycling Association
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• v.20 no.3
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• pp.27-33
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• 2012

According to the statistics of the Ministry of Environment, the emission of sewage sludge is increased by 7~9% yearly. In the future, it will be increased continuously because of extension of sewage disposal plants, high class treatment for removing nitrogen and phosphorus. Until now, we have depended on reclamation for lots of quantity and some part has been treated by ocean emission. But, direct reclamation of organic waste will be prohibited and even ocean emission will be prohibited now, so the treatment of sludge is put on emergency alert. Bio-gas can be produced by applying anaerobic digestion method for the recycling or refuse derived fuel can be conducted by applying carbonization method. However, the process is difficult, causes bad smell and makes it the second waste, so it cannot be practical method in fact. This study applied a fluidized bed combustor for sewage sludge treatment technologies that can actually take advantage of key technologies in order to verify its purpose is to demonstrate selected. If applying the fluidized bed combustor, it can be easily utilized as the replaced resource of energy(fuel) in the countries whose energy resources are insufficient, like our country. Especially, if applying only original strengths of the fluidized bed combustor sufficiently, the sewage sludge can be treated simply, eco-friendly, sanitarily and economically. Particularly, it is verified as the energy technology suitable for government's green growth policy.

• Journal of Korea Technology Innovation Society
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• v.2 no.2
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• pp.290-308
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• 1999

In this study a system for the treatment or recyling of organic wastes from both urban and rural area was recommended. It was developed based on the resource recovery system regarding human being by four tectnologies; forage, methane production, high-grade composting and complete decomposition. High quality compost can be produced by combining several kind of wastes produced from urban and agricultural areas. High quality compost must possess not only general characteristics of ordinary compost, but also a superior ability to improve the soil properties and must contain more nutrients for plant. Cedar chips were recommended as the main bulking agent to adjust moisture contents and air permeability. Charcoal and zeolite can be used not only as the second bulking agent but also as fertilizer for improve the soil amendment. Complete decomposition of organic wastes is defined by organic matter being completely converted to $CO_2$ and water. All the input water was evaporated by the heat produced through the oxidation of organic matter, In the present study, the complete treatments were successfully achieved for Shochu wastewater, swine wastes, thickened excess sewage sludge, wastes produced by Chinese restaurant and anaerobic digested sludge. First of all, recycling center of organic wastes should be established for the protect the environments and effective recovery of organic resources. This may means the way to derive the recovery of human value.

• Journal of Korean Society on Water Environment
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• v.34 no.1
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• pp.121-131
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• 2018

Domestic sewage treatment plants (STPs) consume about 0.5 % of total electric energy produced annually, which is equivalent to 207.7 billion Korean won per year. To minimize the energy consumption and as a way of mitigating the depletion of energy sources, the sewage treatment strategy should be improved to the level of "energy positive". The core processes for the energy positive sewage treatment include A-stage for energy recovery and B-stage for energy-efficient nitrogen removal. The integrated process is known as the A/B-process. In A-stage, chemically enhanced primary treatment (CEPT) or high rate activated sludge (HRAS) processes can be utilized by modifying the primary settling in the first stage of sewage treatment. CEPT utilizes chemical coagulation and flocculation, while HRAS applies returned activated sludge for the efficient recovery of organic contents. The two processes showed organic recovery efficiencies ranging from 60 to 70 %. At a given recovery efficiency of 80 %, 17.3 % of energy potential ($1,398kJ/m^3$) is recovered through the anaerobic digestion and combustion of methane. Besides, anaerobic membrane bioreactor (AnMBR) can recover 85% of organic contents and generate $1,580kJ/m^3$ from the sewage. The recovered energy is equal to the amount of energy consumption by sewage treatment equipped with anaerobic ammonium oxidation (ANAMMOX)-based B-stage, $810{\sim}1,620kJ/m^3$. Therefore, it is possible to upgrade STPs as efficient as energy neutral. However, additional novel technologies, such as, fuel cell and co-digestion, should be applied to achieve "energy positive" sewage treatment.

• Journal of Korean Society on Water Environment
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• v.36 no.1
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• pp.55-68
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• 2020

Because of the intensified environmental problems such as climate change and resource depletion, sewage treatment technology focused on energy management has recently attracted attention. The conversion of primary sludge from the primary sedimentation tank and excessive sludge from the secondary sedimentation tank into biogas is the key to energy-positive sewage treatment. In particular, the primary sedimentation tanks recover enriched biodegradable organic matter and anaerobic digestion process produces methane from the organic wastes for energy production. Such technologies for minimizing oxygen demand are leading the innovation regarding sewage treatment plants. However, sewage treatment facilities in Korea lack core technology and operational know-how. Actually, the energy potential of sewage is higher than sewage treatment energy consumption in the sewage treatment, but current processes are not adequately efficient in energy recovery. To improve this, it is possible to apply chemically enhanced primary treatment (CEPT), high-rate activated sludge (HRAS), and anaerobic membrane bioreactor (AnMBR) to the primary sedimentation tank. To maximize the methane production of sewage treatment plants, organic wastes such as food waste and livestock manure can be digested. Additionally, mechanical pretreatment, thermal hydrolysis, and chemical pretreatment would enhance the methane conversion of organic waste. Power generation systems based on internal combustion engines are susceptible to heat source losses, requiring breakthrough energy conversion systems such as fuel cells. To realize the energy positive sewage treatment plant, primary organic matter recovery from sewage, biogas pretreatment, and co-digestion should be optimized in the energy management system based on the knowledge-based operation.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.5
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• pp.401-410
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• 2002

Concerns for energy conservation, environmental pollution, and the fact that organic wastes account for a major portion of our waste materials, have created the interest of biogas, which usually contains about 60 to 70 percent methane, 30 to 40 percent carbon dioxide, and other gases, including ammonia, hydrogen sulfide, mercaptans and other noxious gases. Cyclone combustors are used for homing a wide range of fuels such as low calorific value gas, waste water, sludge. coal, etc. The 3-dimensional swirling flow, combustion and emission in a tangential inlet cyclone incinerator under different inlet conditions are simulated using a standard k-s turbulence model and ESCRS (Extended Simple Chemically-Reacting System) model. The commercial code Phoenics Ver.3.4 was used for the present work. The main parameters considered in this work are inlet velocity and air to fuel ratio. The results showed that the change of operating conditions had an influence on the shape and size of recirculation zones, mixture fraction and axial velocity which are important factors for combustion efficiency and emission behavior. The application of this kind of computer program seams to be promising as a potential tool for the optimum design of a cyclone combustor with low emission.

• Journal of the Korean Society of Combustion
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• v.22 no.1
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• pp.14-22
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• 2017

Co-firing of renewable fuel in coal fired boilers is an attractive option to mitigate $CO_2$ emissions, since it is a relatively low cost option for efficiently converting renewable fuel to electricity by adding biomass as partial substitute of coal. However, it would cause reducing plant efficiency and operational flexibility, and increasing operation and capital cost associated with handling and firing equipment of renewable fuels. The aim of this study is to investigate the effects of biomass co-firing on $CO_2$ emission and capital/operating cost. Wood pellet, PKS (palm kernel shell), EFB (empty fruit bunch) and sludge are considered as renewable fuels for co-firing with coal. Several approaches by the co-firing ratio are chosen from previous plant demonstrations and commercial co-firing operation, and they are evaluated and discussed for $CO_2$ reduction and cost estimation.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.4
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• pp.223-231
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• 2012

The purpose of this study is to investigate basically the mechanism of heat transfer by the resolution of complex fluid flow inside a sophisticated designed screw dryer for the treatment of sewage sludge by using numerical analysis and experimental study. By doing this, the result was quite helpful to obtain the design criteria for enhancing drying efficiency, thereby achieving the optimal design of a multiple screw type dryer for treating inorganic and organic sludge wastes. One notable design feature of the dryer was to bypass a certain of fraction of the hot combustion gases into the bottom of the screw cylinder, by the fluid flow induction, across the delicately designed holes on the screw surface to agitate internally the sticky sludges. This offers many benefits not only in the enhancement of thermal efficiency even for the high viscosity material but also greater flexibility in the application of system design and operation. However, one careful precaution was made in operation in that when distributing the hot flue gas over the lump of sludge for internal agitation not to make any pore blocking and to avoid too much pressure drop caused by inertial resistance across the lump of sludge. The optimal retention time for rotating the screw at 1 rpm in order to treat 200 kg/hr of sewage sludge was determined empirically about 100 minutes. The corresponding optimal heat source was found to be 150,000 kcal/hr. A series of numerical calculation is performed to resolve flow characteristics in order to assist in the system design as function of important system and operational variables. The numerical calculation is successfully evaluated against experimental temperature profile and flow field characteristics. In general, the calculation results are physically reasonable and consistent in parametric study. In further studies, more quantitative data analyses such as pressure drop across the type and loading of drying sludge will be made for the system evaluation in experiment and calculation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.6
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• pp.584-590
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• 2012

In this study, we have conducted a work on homogenizer development which is operated by high shearing force generated by stator and rotor inside it. To investigate the performance for homogenization and atomization of homogenizer, Bunker-C (IFO 380 cSt) was used as a fuel for experiment. Pre-treatment of bunker-C was carried out with homogenizer developed in this study. Oil purifier was used to investigate effect of oil sludge reduction after pre-treatment. Experimental result showed that the amount of sludge of fuel oil after pre-treatment with homogenizer has decreased by 13 %. To confirm combustion efficiency, Bunker-C which have pre-treatment with homogenizer and purified after are burned in boiler system. The result showed that CO concentration in exhaust gas was decreased. These results mean that if the homogenizer which is developed in this study for marine fuel oil is applied on real vessels, oil costs and operating costs can be reduced.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.19-20
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• 2013

The cofiring of renewable fuel in coal fired boilers is an attractive option to mitigate $CO_2$ emissions, since it is relatively low cost option for efficiently converting renewable fuel to electricity by adding biomass as partial substitute of coal. However, it would lead to reduce plant efficiency and flexibility in operation, and increase operation cost and capital cost associated with renewable fuels handling and firing equipment. The aim of this study is to investigate reduction of carbon dioxide at varying percentage of biomass in fuel blend to the boiler biomass, and estimate operation and capital cost. Wood pellet, PKS (palm kernel shell), EFB (empty fruit bunch) and sludge are considered as a renewable fuels for a cofiring with coal. Several approaches by the cofiring ratio are chosen from past plant demonstrations and commercial cofiring operation, and they are evaluated and discussed for CO2 reduction and cost estimation.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.15 no.3
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• pp.1-6
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• 2019

The basalt fiber, which is found to be non-toxic and harmless to the human body, is expected to become a trend for industrial fibers as they have better properties of non-combustion, heat-resistant, soundproof, absorbent, moistureproof, wear-resistant, corrosion resistant, lightweight, and high strength properties. Thus, in this study, we analyzed the chemical compositions of basalt produced at seven sites on Jeju Island for making a high value inorganic insulation material. The results showed that the MgO content of basalt collected from the eastern part of Jeju Island was higher than 7.5 percent, while that of the western region was less than 6 percent.