• Environmental Engineering Research
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• 제18권3호
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• pp.163-168
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• 2013

In this study, an innovative media, iron mixed ceramic pellet (IMCP) has been developed for arsenic (As) removal from groundwater. A porous, solid-phase IMCP (2-3 mm) was manufactured by combining clay soil, rice bran, and Fe(0) powder at $600^{\circ}C$. Both the As(III) and As(V) adsorption characteristics of IMCP were studied in several batch experiments. Structural analysis of the IMCP was conducted using X-ray absorption fine structure (XAFS) analysis to understand the mechanism of As removal. The adsorption of As was found to be dependent on pH, and exhibited strong adsorption of both As(III) and As(V) at pH 5-7. The adsorption process was described to follow a pseudo-second-order reaction, and the adsorption rate of As(V) was greater than that of As(III). The adsorption data were fit well with both Freundlich and Langmuir isotherm models. The maximum adsorption capacities of As(III) and As(V) from the Langmuir isotherm were found to be 4.0 and 4.5 mg/g, respectively. Phosphorus in the water had an adverse effect on both As(III) and As(V) adsorption. Scanning electron microscopy results revealed that iron(III) oxides/hydroxides are aggregated on the surface of IMCP. XAFS analysis showed a partial oxidation of As(III) and adsorption of As(V) onto the iron oxide in the IMCP.

• 한국수산과학회지
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• 제40권2호
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• pp.73-78
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• 2007

The suitability of a flexible fiber filter for removing suspended solid (SS) in a recirculating aquaculture system was evaluated. This study focused on variation in the performance with a change in filtering time, influent water quality, and filtering mode duration. The particle distribution diagram of the filter effluent showed that the number of particles bigger than $5-8{\mu}m$ decreased dramatically, and the removal efficiency exceeded 80%. Although the removal efficiencies of SS and chemical oxygen demand (COD) were dependent on the quality of the influent, the SS and COD concentrations of the effluent were not affected by the influent concentrations. This was despite the deterioration if water quality after feeding in the rearing tank. The performance of the filter was not affected by the filtering mode duration, feeding conditions, or filtering time. The SS concentration and turbidity of the recirculating-type rearing tank were 30% and 50% lower, respectively, than of the a non-recirculating-type rearing tank under the same operating conditions. The flexible fiber filter was applicable to a recirculating aquaculture system that uses plenty of seawater, based on its low filtering resistance $(2kg_f/cm^2)$, high flux $(330m^3/m^2/hr)$, and high fine particle removal efficiency (80%, $5-8{\mu}m$).

• Membrane and Water Treatment
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• 제7권5호
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• pp.403-416
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• 2016

The possibility of using carica papaya leaf powder for removal of copper from wastewater as a low cost adsorbent was explored. Different parameters that affect the adsorption process like initial concentration of metal ion, time of contact, adsorbent quantity and pH were evaluated and the outcome of the study was tested using adsorption isotherm models. A maximum of 90%-94.1% copper removal was possible from wastewater having low concentration of the metal using papaya leaf powder under optimum conditions by conducting experimental studies. The biosorption of copper ion was influenced by pH and outcome of experimental results indicate the optimum pH as 7.0 for maximum copper removal. Copper distribution between the solid and liquid phases in batch studies was described by isotherms like Langmuir adsorption and Freundlich models. The adsorption process was better represented by the Freundlich isotherm model. The maximum adsorption capacity of copper was measured to be 24.51 mg/g through the Langmuir model. Pseudo-second order rate equation was better suited for the adsorption process. A dynamic mode study was also conducted to analyse the ability of papaya leaf powder to remove copper (II) ions from aqueous solution and the breakthrough curve was described by an S profile. Present study revealed that papaya leaf powder can be used for the removal of copper from the wastewater and low cost water treatment techniques can be developed using this adsorbent.

• 상하수도학회지
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• 제22권2호
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• pp.179-182
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• 2008

The KIDEA process, occurred in single reactor, is operated by three consequential steps, i.e., aerobic, settling, and discharge while introducing wastewater into the bottom of reactor continuously. It could accomplish biological oxidation (BOD), nitrification, denitrification (T-N), phosphate removal (T-P), and solid separation (SS) through the operational mode mentioned. Especially, this system has removed the T-P by wasting certain amount of sludge at the end of aeration phase during 5~10 minutes and not returned the activated sludge into the reactor, that is, no RAS (Return Activated Sludge). All running mode and instrumentation were controlled by the PLC equipment automatically. In this study, therefore, we have evaluated T-P removal efficiency and moisture content (MC) performance under the different excess sludge wasting mode. T-P track study and MC with TS concentration were analyzed during aerobic and settling phase. It has revealed that there was no significant difference of released T-P concentration between the first case which waste the sludge at the end of aerobic phase (0.2mg/L) and the second case which waste the sludge at 40 min of settling phase (0.25mg/L). Also, dewatering duration and MC have decreased 1.7% when TS concentration was increased from 0.31% to 0.5% during aerobic condition. Hence, it has concluded the system performance was less influenced by the operation time change of PLC program.

• 한국환경과학회지
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• 제13권1호
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• pp.47-53
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• 2004

A biofiltration system using activated carbon/polyurethane composite as solid support inoculated with Bacillus sp. was developed for treating a gaseous stream containing high concentrations of H$_2$S. The effects of operating condition such as the influent H$_2$S concentration and the empty bed contact time (EBCT) on the removal efficiency of H$_2$S were investigated. The biofilter showed the stable removal efficiencies of over 99 ％ under the EBCT range from 15 to 60 sec at the 300 ppmv of H$_2$S inlet concentration. When the inlet concentration of H$_2$S was increased, the removal efficiencies decreased, reaching 95 and 74％, at EBCTs of 10 and 7.5 sec, respectively. The maximum elimination capacity in the biofilter packed with activated carbon/polyurethane composite media was 157 g/m$^3$/hr.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.219-222
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• 2004

Removal characteristics of Mn and Co was studied from the contaminated solutions via surface reaction with various calcium carbonate (calcite). Synthetic calcium carbonates which has different surface morphology as well as surface areas were prepared by a spontaneous precipitation method and used. Mn and Co removal behavior by the different solid surface demonstrate characteristic sorption behaviors depend on the type of calcite used, such as surface area or surface morphology. Calcium carbonate crystals (mostly calcite) which exhibit complicated surface morphology (c-type) shows strong sorption affinity for Mn and Co removal via sorption than on the a-type or b-type calcite crystals of less complicated surfaces. The applicability of two kinetic models, the pseudo-first-order kinetic equation and the Elovich kinetic model was examined on these sorption behavior. Elovich kinetic model was found more suitable to explain the very early stage adsorption kinetics, while the pseudo-first-order kinetic equation was successfully fitted for the adsorption kinetics after 50 hours.

• 한국미생물·생명공학회지
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• 제24권5호
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• pp.597-603
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• 1996

This study was carried out to examine degradation characteristics of microalgae Chlorella vulgaris in methane fermentation. We measured COD and VS reduction, gas and methane productivity, VFA (volatile fatty acid), respectively. Then we calculated material balance and hydrolysis rates in soluble and solid material. The substrate concentration was controlled from 14 gCOD$_{cr}$/l to 64 gCOD$_{cr}$/l in batch cultures, and HRT (hydraulic retention time) controlled from 2 days to 30 days in continuous experi- ments. The results were as follows. In batch culture, accumulated gas productivity increased with the increase of the substrate concentration. The SS and VSS was removed all about 30% increase of substrate concentration and the most of the degradable material removed during the first 10 days. The curve of gas and methane production rate straightly increased until substrate concentration is 26 gCOD$_{cr}$/l. In continuous culture experiments, the removal rates at HRT 10days were 20% for total COD and TOC, respectively. At longer HRT, there was no increase in the removal efficiency. At HRT 15 days, the removal rates were 30% for SS and VSS, respectively. Soluble organic materials were rapidly degraded, and so there was no accumulated. Soluble COD concentration was not increase regardless of HRT-increasing. That meaned the hydrolysis was one of the rate-limiting stage of methane fermentation. The first-order rate constants of hydrolysis were 0.23-0.28 day$^{-1}$ for VSS, and 0.07-0.08 day$^{-1}$ for COD.

• 한국축산시설환경학회지
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• 제1권1호
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• pp.47-53
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• 1995

An efficient Treatment of animal wastewater is one of the hot issues for preventing the environmental pollution. It should be established the design parameter in order to purify the animal wastewater. A test is carried on in the pilot plant as a simplified activated sludge process. A vibration sieve separator is deviced to keep the pollution load constant by means of separation of solid matter. The BOD removal efficiency of the vibration sieve showed over 50%. As the test results, the BOD contents of the influent was in average of 3,000 mg/I and that of the effluent 85 mg/I. So, the BOD removal rate showed 97% in average. The SS-contents in the primary chamber was about 3,300 mg/I and that of effluent 92 mg/I. The SS removal efficiency showed 97%. The removal rate of total nitrogen and phosphore were in average of 82% respectively. Carrying out in winter season, it showed relatively good results; The design parameter approved in this test can be applied to the full-time farmers.

• 한국안전학회지
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• 제14권1호
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• pp.78-85
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• 1999

The removal characteristics of H$_2$S from IGCC process over the natural manganese ore(NMO) containing several metal oxides($MnO_x$ : 51.85%, $FeO_y$ : 3.86%, CaO : 0.11%) were carried out in a batch type fluidized bed reactor(I.D.=40mm, height=0.8m). The $H_2S$ breakthrough curves were obtained as a function of temperature, initial gas velocity, initial gas concentration, and aspect ratio. The effect of particle size ratio and particle mixing fraction on $H_2S$ removal were investigated with binary system of different particle size. From this study, the adsorption capacity of $H_2S$ increased with temperature but decreased with excess gas velocity. The breakthrough time for $H_2S$ is reduced as the gas velocity is increased which leaded to gas by-passing and gas-solid contacting in a fluidized bed reactor. The results of the binary particle system with different size in batch experimental could predict to improve the behavior of continuous process of $H_2S$ removal efficiency. The natural manganese ore could be considered as potential sorbent in $H_2S$ removal.

• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.219-230
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• 2018

The present study examined a moving bed biofilm reactor (MBBR) bioreactor on a laboratory scale for simultaneous removal of atrazine, organic carbon, and nutrients from wastewater. The maximum removal efficiency of atrazine, chemical oxygen demand (COD), total phosphorus (TP) and total nitrogen (TN) were 83.57%, 90.36%, 90.74% and 87.93 respectively. Increasing salinity up to 40 g/L NaCl in influent flow could inhibit atrazine biodegradation process strongly in the MBBR reactor.Results showed that MBBR is so suitable process for efficiently biodegrading of atrazine and nitrogen removal process was based on the simultaneous nitrification-denitrification (SND) process.