• Journal of Environmental Science International
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• v.15 no.6
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• pp.513-525
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• 2006

In recent decades, biofiltration has been widely accepted for the treatment of contaminated air stream containing low concentration of odorous compounds or volatile organic compounds (VOCs). In this study, conventional biofilters packed with flexible synthetic polyurethane (PU) foam carriers were operated to remove toluene from a contaminated air stream. PU foams containing various amounts of pulverized activated carbon (PAC) were synthesized for the biofilter media and tested for toluene removal. Four biofilter columns were operated for 60 days to remove gaseous toluene from a contaminated air stream. During the biofiltration experiment, inlet toluene concentration was in the range of 0-150 ppm and EBRT (i.e., empty bed residence time) was kept at 26-42 seconds. Pressure drop of the biofilter bed was less than 3 mm $H_2O/m$ filter bed. The maximum removal capacity of toluene in the biofilters packed with PU-PAC foam was in the order of column II (PAC=7.08%) > column III (PAC=8.97%) > column I (PAC=4.95%) > column IV (PAC=13.52%), while the complete removal capacity was in the order of column II > column I > column III > column IV. The better biofiltration performance in column II was attributed to higher porosity providing favorable conditions for microbial growth. The results of biodegradation kinetic analysis showed that PU-PAC foam with 7.08% of PAC content had higher maximum removal rate ($V_m$=14.99 g toluene/kg dry material/day) than the other PU-PAC foams. In overall, the performance of biofiltration might be affected by the structure and physicochemical properties of PU foam induced by PAC content.

• Applied Biological Chemistry
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• v.37 no.6
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• pp.472-479
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• 1994

This study was conducted to determine the effective removal method of THMs and humic material in drinking water when the doses of oxidants, coagulants, and activated carbon, and the points of oxidants treatment were changed in the drinking water treatment process. The inhibition of THMs formation and the removal of humic matter were more effectively achieved by $ClO_2$ than by other oxidants, $Cl_2,\;NH_2Cl,\;KMnO_4\;and\;O_3$. By changing the point of oxidant treatment, the formation of THMs was reduced by about 36.7 to 8.2% on treatment after coagulation, but the content of humic matter was not affected. The coagulation efficiency of alum and ferric sulfate to coagulate organic materials in water was affected by the molecular weight of humic matter in drinking water. The treatment of activated carbon after filtration was found to be more effective than that before oxidation in inhibiting THMs formation and removing THMs.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.5
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• pp.539-549
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• 2007

To establish effective and prompt measures for energy conservation in public wastewater treatment plants in Korea, energy consumption rates in 233 utilities in 9 provinces and 7 metropolitan cities are investigated and compared to the rest of the world. Mean load factor for wastewater treatment utilities is 74.9% and those for influent pumps and aeration blowers are 56.2% and 61.0%, respectively. Mean electrical energy usages as the key performance indicators are $0.243kWh/m^3$ for overall sewage treatments and 2.07 kWh per unit kg BOD removal. Digester gas as one of major byproducts in the process amounts to $382,000m^3/day$ nationwide. While major part of the digester gas is used for sludge heating, only 7.3% of the gas is utilized for electricity generation. Both efficiencies for BOD removal and digestion gas generation are considerably lower than those in USA and EU utilities due to low concentration of organic material in influent wastewater. Such low energy regeneration, in turn, results in significantly higher energy consumption in Korean plants, compared to that in USA and EU ones.

• The KSFM Journal of Fluid Machinery
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• v.17 no.2
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• pp.35-40
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• 2014

The optimal removal efficiency to develop wastewater treatment system using the magnetic ion exchange resin. The secondary sedimentation effluent of wastewater in W wastewater treatment plant located in Gyeong-gi Province was used as the influent. To compare the sedimentation effluent reacted with the magnetic ion exchange resin to the influent, the concentrations of CODmm, TN, $NO{_3}^-$-N and TP were measured. The flux of the influent and HRT were set to 250 mL/min, 10 min, respectively, and BVTR has adjusted to 200, 150, 100. The removal efficiency of CODmn, TN, $NO{_3}^-$-N and TP in the 200 BVTR from 71%, 40.37%, 46.34%, 42.03%, 150 BVTR from 55.22%, 37.83%, 50.38% 41.6% and 100 BVTR from 74%, 59.15%, 79.94%, 79.16%, respectively. The results on 200 BVTR, 150 BVTR, 100 BVTR tests show that 100 BVTR is the optimal factor capable of the highest rate of rejection of the organic material.

• Environmental Engineering Research
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• v.21 no.1
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• pp.36-44
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• 2016

Constructed wetlands are established efficient technologies and provide sustainable solution for wastewater treatment. Similarly, biochar, which is an organic material, produced by means of pyrolysis, offers simple and low cost techniques to treat water and reduce carbon footprint. Combining both of these technologies can greatly augment the efficiency of the system. The objective of this study was to evaluate the efficiency of constructed wetlands by using biochar as media. Horizontal wetland beds with dimension ($1m{\times}0.33m{\times}0.3m$) were prepared using gravels and biochar, and cultivated with the Canna species. Synthetic wastewater was passed through these beds with average flow rate of $1.2{\times}10^{-7}m^3/sec$ achieving a retention time of three days. Pollutant removal performance was compared between the controlled and experimental wetland beds. This study reveals that the wetland with biochar were more efficient as compared to the wetland with gravels alone with average removal rate of 91.3% COD, 58.3% TN, 58.3% $NH_3$, 92% $NO_3-N$, 79.5% TP, and 67.7% $PO_4$.

• Membrane and Water Treatment
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• v.13 no.2
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• pp.97-104
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• 2022

With a small particle size, specific surface area and chemical nature, Pd/Cu-Fe nanocomposites can efficiently remove the organic compounds. In order to understand the applicability for in situ remediation of contaminated groundwater, the degradation of p-nitrophenol by Pd/Cu-Fe nanoparticles was investigated. The degradation results demonstrated that these nanoparticles could effectively degrade p-nitrophenol and near 90% of degradation efficiency was achieved by Pd/Cu-Fe nanocomposites for 120 min treatment. The efficiency of degradation increased significantly when the Pd content increased from 0.05 wt.% and 0.10 wt.% to 0.20 wt.%. Meanwhile, the removal percentage of p-nitrophenol increased from 75.4% and 81.7% to 89.2% within 120 min. Studies on the kinetics of p-nitrophenol that reacts with Pd/Cu-Fe nanocomposites implied that their behaviors followed the pseudo-first-order kinetics. Furthermore, the batch experiment data suggested that some factors, including Pd/Cu-Fe availability, temperature, pH, different ions (SO42-, PO43-, NO3-) and humic acid content in water, also have significant impacts on p-nitrophenol degradation efficiency. The recyclability of the material was evaluated. The results showed that the Pd/Cu-Fe nanoparticles have good recycle performance, and after three cycles, the removal rate of p-nitrophenol is still more than 83%.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.10
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• pp.975-983
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• 2008

In view of previous investigations that the outermost zone of porous media displays the most vigorous removal of organic contaminant, a novel filtration apparatus of cylinder-shaped porous material (polyester fiber) was applied to the Samcheonji reservoir in Gyeongsan to assess its ability to remove contaminants from reservoir water. The apparent mechanism of purification is that organic pollutant dispersed in the water is collected by the matrix to be degraded by microbes in due course. Data obtained from the experiment appear promising; 19$\sim$27% decrease in COD$_{Cr}$, 37$\sim$43% reduction in COD$_{Mn}$, BOD$_5$ diminution between 67$\sim$81%, 93% decrease in turbidity, and 99% removal of Suspended Solids. The results suggest that this device may be a valuable supplementary means to ameliorate the quality of reservoir water.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.28-34
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• 2012

In this study, we operated a UASB (upflow anaerobic sludge blanket) reactor by using foodwaste leachate as a raw material with the method of Mesophilic Digestion ($35{\pm}0.5^{\circ}C$) and Thermophilic Digestion ($55{\pm}0.5^{\circ}C$). During 20 days of operating time with the Mesophilic Digestion, the recirculation ratio of effluent was stepwisely changed in every five days. Thermophilic Digestion was carried out at the same condition for Mesophilic Digestion. Results showed that the organic removal efficiency of Mesophilic Digestion was over 90% and the yield of methane production was from 66 up to 70%. The organic removal efficiency of Thermophilic Digestion was over 80% and the yield of methane production was between 62 to 68%. Also, when UASB reactor was operating to over the 3Q effluent recirculation, the experiment could be carried out economically and stably.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.3
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• pp.93-102
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• 2023

This study investigated the possibility of treating heavy metal pollutants existing in the air in addition to simultaneously removing NOx and SOx by injecting oxidizing and reducing agents into a scrubber into a microbubble device to create an eco-friendly method that does not generate secondary pollutants. Lead compound (Pb) was selected as the heavy metal substance in the air to be treated with microbubbles, and the removal efficiency was confirmed. By treating microbubbles by connecting them to a scrubber, it was confirmed that not only NOx and SOx but also heavy metal substances in the air were reduced, cost was reduced, and secondary environmental pollutants were not generated. Through this study, it was possible to simultaneously remove NOx, SOx, and heavy metals at low cost by applying an eco-friendly method, rather than the existing high-cost treatment method such as SCR. If oxidizing agent, reducing agent, and microbubbles are used appropriately, economical and efficient air pollution can be achieved. Since material processing was possible, it is expected to be helpful in the technological development of environmental prevention facilities.

• Journal of the Korea Organic Resources Recycling Association
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• v.32 no.2
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• pp.15-25
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• 2024

In this study, the regeneration effect of pressurized water and ultrasonic cleaning was investigated for contaminated filter cloth from the sewage sludge filter press process. For this purpose, contaminated filter cloth was collected from a 3-ton sewage sludge hydrothermal carbon treatment filter press. First, the contamination characteristics were analyzed. According to the location of the filter cloth, air permeability and unit mass were measured, and compared with the values of a new filter cloth. Next, the results were mapped over the entire area to evaluate the contamination characteristics. Finally, pressure cleaning at 3 bar and ultrasound at frequencies of 34, 76, 120, and 168 kHz were performed on the contaminated filter cloth. In addition, the cleaning efficiency was evaluated by 3 levels of contamination degree. As a result, pore contamination occurred mainly at the bottom and both sides of the filter cloth, where the filter material was continuously injected and compressed. Surface contamination appeared evenly over the entire area. As a result of washing, air permeability increased by 1.3-3.1%p and contaminant removal was by 2.7-4.4% under pressure. In ultrasonic cleaning, air permeability increased by 12.5-61.5%p and contaminants were removed by 2.7-29.2%. In ultrasonic cleaning the lower the frequency, the higher air permeability and contaminant removal rate. Also, The higher pore contamination level, the better the air permeability improvement and contaminant removal.