• Journal of Environmental Science International
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• v.27 no.6
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• pp.447-456
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• 2018

In this research, the target process was a modified type of a conventional aeration tank with four different influent feeding points and alternated aeration to obtain nitrogen removal. For more accurate switching of influent feeding, the process was operated under a designed control strategy based on monitoring of $NH_4-N$ and $NO_X-N$ concentrations in the tank. However, the strategy did have some limitations. For example, it was not sensitive to detecting the end of each reaction when losing the balance between nitrification and denitrification of each opposite part of biological tank. To overcome the limitations of the existing control strategy, a diagnosis-based control strategy was suggested in this research using the diagnosis results classified as normal (N), ammonia accumulation (AA) and nitrate accumulation (NA). Using the pre-designed rules for control actions, the aeration and volume of the aerated part of the reactor could be increased or decreased at a fixed mode time. In simulations of the suggested diagnosis-based control strategy, the $NH_4-N$ and $NO_X-N$ removal rates in the reactor were maintained at higher levels than those of the existing control strategy.

• Environmental Engineering Research
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• v.16 no.4
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• pp.213-218
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• 2011

The two-stage intermittent aeration activated sludge process (IAP) and dynamic-flow intermittent aeration activated sludge process (DFP) were investigated for the nutrient removal of domestic wastewater. Three sets of IAP and one set of DFP were operated. The fermented settled sludge taken from the primary settling tank was added to two IAP and one DFP as an external electron donor, with one IAP, in which an external carbon source was not added, as a control. All the systems were operated at a sludge retention time of 20 days and a hydraulic retention time of 12 hr. A Higher denitrification rate was observed with the fermented settled sludge for the denitrification compared to the process without the addition of the organic source. The result indicates that the fermented acid from the primary domestic sludge has been proved to be an excellent electron donor for denitrification and biological phosphorus removal with IAP and DFP in treating relatively low C/N ratio(Carbon / Nitrogen ratio) wastewater. Phosphate accumulating organisms have a capability of competing with denitrifiers in the presence of volatile organic acids under anoxic conditions.

• Journal of Environmental Health Sciences
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• v.31 no.5 s.86
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• pp.404-410
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• 2005

The pH efforts on the removal of 1,4-dioxane and the biodegradobility enhancement of dioxane contaminated water were investigated using $O_3/H_2O_2$ baled advanced oxidation process. Experiments were conducted using a bubble column reactor under different initial pH. The $O_3/H_2O_2$ process effectively converted 1,4-dioxane to more biodegradable intermediates which had a maximum $BOD_5$ enhancement at pH 11 within the experimental range, precisely, when the initial pH increased, $BOD_5$ enhanced. However, in case of removal efficiencies of 1,4-dioxane during $O_3/H_2O_2$ oxidation the optimum condition was shown at pH 9 compared with pH 6 and 11. TOC and COD values were not largely changed for all reaction time. From the results of 1,4-dioxane removal efficiency, TOC, COD, and $BOD_5$ enhancement with reaction time, it was surely observed that 1,4-dioxane was just converted to biodegradable materials, not completely oxidized to carbon dioxide.

• Particle and aerosol research
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• v.5 no.4
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• pp.189-197
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• 2009

Wet-type particulate removal system is employed in most of ironmaking processes. These de-dusting systems require additional downstream aggregates for treatment of water and for drying of the collected slurry. Thus dried slurry can be pressed in shape of briquettes and recycled in the steelmaking process. Different from the wet-type, the dry-type particulate removal systems generate no slurry. A high-temperature, high-pressure de-dusting system with inertial inlet was developed. The target application of this system was to remove particulate matter generated from the novel ironmaking process and other steelmaking processes. In this study we conducted tests with this newly developed system to evaluate the performance of the silica-carbide (SiC) ceramic filters. In addition, for purpose of comparison, we also conducted tests with a unit which has conventional direct inlet. Fe-Particles collected from the novel ironmaking process were used in our tests as test dusts. The temperature and the pressure were kept constant at their respective values $800^{\circ}C$ and $3kg_f/cm^2$.

• Journal of Korea Society of Digital Industry and Information Management
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• v.12 no.2
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• pp.7-14
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• 2016

In this paper presents a low power algorithm using a feasible cluster generation method considered glitch. The proposed algorithm is a method for reducing power consumption of a given circuit. The algorithm consists of a feasible cluster generation process and glitches removal process. So that glitches are not generated for the node to which the switching operation occurs most frequently in order to reduce the power consumption is a method for generating a feasible cluster. A feasible cluster generation process consisted of a node value set, dividing the node, the node aligned with the feasible cluster generation. A feasible cluster generation procedure is produced from the highest number of nodes in the output. When exceeding the number of OR-terms of the inputs of the selected node CLB prevents the signal path is varied by the evenly divided. If there are nodes with the same number of outputs selected by the first highest number of nodes in the input produces a feasible cluster. Glitch removal process removes glitches through the path balancing in the same manner as [5]. Experimental results were compared with the proposed algorithm [5]. Number of blocks has been increased by 5%, the power consumption was reduced by 3%.

• Membrane Journal
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• v.12 no.2
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• pp.67-74
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• 2002

Submerged membrane bioreactor(SMBR) and reverse osmosis(R/O) systems treated dye wastewater for reusing of industrial water. The permeate fluxes of SMBR at 20-25 cmHg of lab. test and field test were 10 LMH($1/m^2$.hr) all test. Removal efficiencies of CODcr, $COD_{Mn}$ and T-N were 93%, 90% and 60% in the SMBR, respectively The advanced treatment of combined process(SMBR+R/0) was accomplished for increasing the removal efficiency of non-biodegradable materials and T-N. Therefore, the removal efficiency of T-N obtained in 80% above, then nitrogen concentration was under 15 mg/L. The combined process(SMBR+R/0) was suitable to reuse of the dye wastewater.

• Journal of Korean Society of Water and Wastewater
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• v.14 no.2
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• pp.147-156
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• 2000

In this study, the optimal operation parameters of MLE(Modified Ludzack-Ettinger) process treating the liquid supernatant separated from the slurry excreta of swine feedlot was studied as a promising biological treatment process. The nitrogen removal characteristics with different volume ratio between nitrification and denitrification reactor and the operational effect with different nitrogen loading rate, and different C/N($COD_{Cr}/TKN$) ratio were investigated. Based on the laboratory results, pilot MLE plant was operated to examine the effect of ambient temperature for five months including winter. The denitrification reactor which is 20% of total volume was proposed as the most optimal volume fraction for nitrification and denitrification. The optimum ratios of F/M and $F_N/M$ were increased with increase of the C/N ratio. However, optimum F/M ratio was changed more rapidly than $F_N/M$ ratio with increase of the C/N ratio. Therefore, MLE process is desirable to be controlled by F/M ratio in the range of high C/N ratio and by $F_N/M$ ratio in the range of low C/N ratio. Pilot MLE plant showed the higher removal efficiencies of COD and TKN in winter than in summer and was operated most stably at the temperature of $20{\sim}25^{\circ}C$ for mixed liqour.

• Journal of Environmental Health Sciences
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• v.19 no.4
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• pp.38-43
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• 1993

The characteristics of food wastewater treatment in an anaerobic packed bed reactor (APBR) with polyurethane as a packing material and sludge bed reactor (ASBR) was studied. The reactor of 9cm-ID, 150cm-height was fed in a continuous mode from bottom of reactor. For the purpose of constant temperature of reactor, water jacket was installed. The used packing materials was polyurethane sponge foam. Methane which was produced by decomposed organics collected at the top of the reactor for using as a fuel. The substrates used were synthetic, mixed and food wastewater. For the acclimatization of microorganisms, mixed wastewater was used. The major analyses were gas production, COD, pH and volatile acids. Based upon the completed works, the results are as follows: When food wastewater was fed the quantity of produced gas was less than that of synthetic wastewater, but food process saw higher methane content than synthetic process. As well as COD removal efficiency of food process reached at about 85%. In aspect of effluent volatile acid, food process showed low concentration of below 500 mg/l, therefore anaerobic reaction stabled. Conclusively food wastewater used can be digested by anaerobic treatment, especially anaerobic packed bed reactor showed 82% of COD removal, 75% of methane content, 10 l of gas production, and anaerobic sludge bed reactor did 79% of COD removal, 75% of methane content, 81 of gas production at 4 kgCOD/m$^3$day, 36$\circ$C.

• Journal of Soil and Groundwater Environment
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• v.19 no.3
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• pp.142-152
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• 2014

In this study, generic characteristics of the acid mine drainage (AMD), removal efficiency of iron, aluminium and manganese by chemical treatment, electrolysis and hybrid process using electrolysis after neutralization were evaluated. The pH of AMD was inversely proportional to the rainfall. In dry-season, the average pH of AMD was ranged from 4.5 to 5.5, showing slight variation. However, the pH of AMD was gradually decreased along with rainfall and dropped to 3.02 in September showing the greatest rainfall. Removal efficiency of heavy metals by chemical treatments using three different neutralizing agents or by electrolysis was low. However, a hybrid process performed with electrolysis after addition of neutralization shows higher removal capacity for heavy metal ions than neutralization-alone and electrolysisalone process.

• Journal of the Semiconductor & Display Technology
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• v.16 no.2
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• pp.55-60
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• 2017

The supercritical $CO_2$ (sc-$CO_2$) mixture and the sc-$CO_2$-based Photoresist(PR) stripping(SCPS) process were applied to the removal of the post etch/ash PR residue on aluminum patterned wafers and the results were observed by scanning of electron microscope(SEM). In the case of MDII wafers, the carbonized PR was able to be effectively removed without pre-stripping by oxygen plasma ashing by using sc-$CO_2$ mixture containing the optimum formulated additives at the proper pressure and temperature, and the same result was also able to be obtained in the case of HDII wafer. It was found that the efficiency of SCPS of ion implanted wafer improved as the temperature of SCPS was high, so a very large amount of MEA in the sc-$CO_2$ mixture could be reduced if the temperature could be increased at condition that a process permits, and the ion implanted photoresist(IIP) on the wafer was able to be removed completely without pre-treatment of plasma ashing by using the only 1 step SCPS process. By using SCPS process, PR polymers formed on sidewalls of metal conductive layers such as aluminum films, titanium and titanium nitride films by dry etching and ashing processes were removed effectively with the minimization of the corrosion of the metal conductive layers.