• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.5
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• pp.9-18
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• 2014

London Convention on the prevention of marine pollution by dumping of wastes and other matter prohibits the deliberate disposal of paper mill sludges at sea. In order to explore the alternative plan on the prohibition of sludge disposal at sea, the biodegradable seedling pot was developed by mixing the sludge with old newspaper (ONP) in appropriate mixing ratios. The C/N ratio of the mixed sludge was below 20, leading to rapid deterioration of the organic matters composing the seedling pot. The increased ONP contents in the seedling pot resulted in the increase of pot thickness and thereafter in the decrease of pot density. Cellulose fibers in ONP promoted water absorption of the pot but AKD addition helped the seedling pot to repel water during raising seedling. Breaking length and burst strength of the seedling pot were improved by addition of wet strength additives but air permeability was a little diminished. Biodegradable rate of the seedling pot in a soil was accelerated by the attack of soil microbes at the beginning, and finally the pot was completely degraded in 150 days in a soil.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.3
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• pp.42-48
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• 2010

The aim of this study is to investigate the influence of driving atomizing nozzle position, the slope of sludge entering tube and supplying air flow rate on the performance of sludge air dryer. This paper deals with optimization of the geometry of the atomizing nozzle for sludge drying using computational fluid dynamics and drying performance test using pilot air dryer. The air drying system was composed of the atomizing nozzle which made high-speed fluid field. dewatered cake was crushed at the high-speed zone as the first step and formed intto dried powder of sphere shape by the collision between particles at the circling zone. The CFD analysis results show when the slope of entering sludge tube is smaller, suction air amount is increased. It is shown that the developed atomizing nozzle is very excellent in the drying performance through pilot test.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.9
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• pp.938-948
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• 2009

In this paper, permanent magnets were used to remove magnetic sludge in the condenser of the power plant. To obtain the flow characteristics and magnetic information that are needed for determining a proper design of the magnetics sludge removal apparatus, numerical simulations were performed through the use of two commercial codes, ANSYS Workbench-Emag and CFX. Experiments were also performed on various kinds and sizes of magnets to obtain the magnetic information through a gauss meter. By analyzing the results of simulations and experiments, the minimum magnetic force that is able to remove the any size of the magnetic sludge in the condenser was calculated, and the design of the removal apparatus was confirmed. The test model which was confirmed by simulations and experiments was made. After testing, the test results were compared with those of numerical simulations and have good agreements.

• Environmental Analysis Health and Toxicology
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• v.29
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• pp.15.1-15.7
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• 2014

Objectives This paper tried to review a recent research trend for the environmental exposure of engineered nanomaterials (ENMs) and its removal efficiency in the nanowaste treatment plants. Methods The studies on the predicted environmental concentrations (PEC) of ENMs obtained by exposure modeling and treatment (or removal) efficiency in nanowaste treatment facilities, such as wastewater treatment plant (WTP) and waste incineration plant (WIP) were investigated. The studies on the landfill of nanowastes also were investigated. Results The Swiss Federal Laboratories for Materials Science and Technology group has led the way in developing methods for estimating ENM production and emissions. The PEC values are available for surface water, wastewater treatment plant effluents, biosolids, sediments, soils, and air. Based on the PEC modeling, the major routes for the environmental exposure of the ENMs were found as WTP effluents/sludge. The ENMs entered in the WTP were 90-99% removed and accumulated in the activated sludge and sludge cake. Additionally, the waste ash released from the WIP contain ENMs. Ultimately, landfills are the likely final destination of the disposed sludge or discarded ENMs products. Conclusions Although the removal efficiency of the ENMs using nanowaste treatment facilities is acceptable, the ENMs were accumulated on the sludge and then finally moved to the landfill. Therefore, the monitoring for the ENMs in the environment where the WTP effluent is discharged or biomass disposed is required to increase our knowledge on the fate and transport of the ENMs and to prevent the unintentional exposure (release) in the environment.

• Journal of Korean Society on Water Environment
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• v.25 no.6
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• pp.964-971
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• 2009

In this paper, activated sludge settling was characterized based on field trip and zone settling tests. Plants used for this study include 5 conventional activated sludge processes and 3 A2O type treatment processes. The treatment capacities are in the range from 12,000 to $250,000m^3$/day. Total number of zone settling tests were 188 set and SVI values representing settling characteristics were from 100 to 300 mL/g. It was found out that zone settling velocity of these examined plant sludges can be approximated by mean values calculated by Keinath and Daigger/Roper models. Based on these three models, solid flux analysis were carried out in order to compare design criteria ($3.96{\sim}6.04kg/m^2-hr$) recommended by Korea Sewage Facility Design Guideline with two models used in USA. The results show that design criteria are only applicable for normal condition in settling characteristics (below SVI 100 mL/g). Solid flux analysis of surveyed plants indicates that most of the plants are operated underload conditions except several plants experiencing poor sludge settling problem. Most of the plants are operated under high sludge blanket depths (SBD).

• Clean Technology
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• v.15 no.3
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• pp.154-164
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• 2009

In 2007, 94% of organic wastewater sludge from industries located in Ulsan was disposed of by ocean dump. The ocean dump of organic sludge would be totally prohibited by the year of 2012. However, there is no alternative but incinerating the sludge from the industries located in Ulsan. Securing the technology for sludge treatment and on-land disposal is very important issue among the industries in the Ulsan Petrochemical Industry Complex. In this study, the material aspects of dried and carbonized sludge as a fuel were evaluated for petrochemical and sewage sludge from Ulsan. The dried and carbonized sludges from the factories producing terephthalic acid, BTX, propylene, chemical textile, etc. of which the low heat value exceeded 3,000 kcal/kg had high potential as a fuel according to the results of thermal characteristic analysis. However, the dried sludges with heat values lower than 2,100 kcal/kg and carbonized sludges, lower than 1,100 kcal/kg containing more Inorganic material from the industries producing pulp, paper, methylamine, amide, etc. had a little potential to be used as a fuel. In most cases, drying the sludge showed better results than carbonization in the aspect of thermal characteristics of sludge.

• Journal of the Korean Applied Science and Technology
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• v.35 no.2
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• pp.540-559
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• 2018

The utilization of sewage sludge for liquid biofuel production is considered as a approach for achieving better energy security, sustainable productivity and economical raw material. Thermochemical technologies of sewage sludge into energy and fuel has been considered as one of the most effective process. Generally, sewage sludge contains more than 80% of moisture, has high metal contents and 14 ~ 20 MJ/kg of calorific value. This paper reviews the technologies of converting sewage sludge to liquid biofuel via three main thermochemical conversion processes namely pyrolysis, transesterification and supercritical. The fuel properties of liquid fuels produced by different technologies from sewage sludge and definition in relevant laws for liquid biofuels in Korea are also discussed.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.1
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• pp.34-39
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• 2017

The recent gradual increase in the energy demand is mostly met by fossil fuel, but the research on and development of new alternative energy sources is drawing much attention due to the limited fossil fuel supply and the greenhouse gas problem. This paper assesses the feasibility of producing fuel energy from a dewatered sewage sludge by microwave-induced pyrolysis with sludge char and graphite receptor. Both receptors produced gas, char, and tar in order from product amount. The gas produced for the sludge char receptor contained mainly hydrogen and methane with a small amount of light hydrocarbons. The graphite receptor generated higher gravimetric tar and generated higher light tar. Through the results, the product gas from the microwave processes of wet sewage sludge might be possible as a fuel energy. But the product gas has to be removed the condensable PAH tars.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.7
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• pp.938-947
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• 2003

In this paper, we derived the formula for estimating the power of the electric motors needed to operate the Decanter-type centrifuge. In the derivation of the formula the sludge-removal torque is to be supplied from the formula derived in the first paper. The intricate nature of the transmission mechanism in the planetary gear trains of the sludge-removal power and torque has been clarified in this second paper. In particular we considered two-motor system, where the main motor drives the machine while the differential-speed control motor plays the role of braking in adjusting the differential speed. Sample calculation for the specific design treated in the first paper showed that the selection criterion for the main motor depends on the lower limit of the differential speed; when the lower limit is set low, it should be selected based on the steadily operating power, while it should be selected based on the starting power when the lower limit is set high. The total power required by both the main motor and the differential-speed control motor increases as the differential speed is decreased. It is suggested that the power loss in the differential-speed control motor could be minimized by attaching an electric generator to it.

• Resources Recycling
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• v.25 no.6
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• pp.58-64
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• 2016

Paper industry discharges many by-products and quantity of PSA (Paper sludge ash) has been increased. In this study, hydration water was added to PSA for use as cement admixture. PSA with added water was mixed with anhydrite and this mixture was used as cement substitute. Physical properties of PSA cement were changed by contents of PSA, but PSA cement containing PSA less than 10% had similar properties to those of OPC. Compressive strength of PSA cement mortar had a certain relationship with $Ca(OH)_2$ content. Compressive strength at 3 days increased, as $Ca(OH)_2$ content increased. However, the strength at 28 days increased, as $Ca(OH)_2$ content decreased.