• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.7
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• pp.3285-3294
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• 2012

A field test on mud flat remediation was carried out in order to observe the effects of the treatments such as microbial dose and an oxygen releasing compound like $CaO_2$. The size of each treatment site was $100m^2$ and the dosage was 3.6 kg per site. The 6 week monitoring showed that pH on two sites was below 7 and ORP increased from .178~-188 mV to .121~-142 mV. In Ignition loss and COD there were no significant changes. Meanwhile nitrogen and phosphorus concentrations changed: ammonia concentration decreased both on control and treatment sites. Nitrate nitrogen decreased more on combined treatment site than on single microbial treatment (11.3% vs. 7.3%) probably because the extra oxygen supplied by $CaO_2$ formed more oxic environment so that the facilitated nitrification might produce more nitrate but the nitrate would be much rapidly released into the water layer out of the sediment. That also explains the total nitrogen reduction(6.1%). Similarly, T-P and $PO_4-P$ reduced by 29% and 31.8%, respectively on combined treatment sites, resulting from the phosphorus release effect though the initial concentrations of the two factors were considerably high.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.523-533
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• 2000

A two-phase anaerobic reactor with submerged membrane system was developed for increasing acidogen concentration and methane recovery. The membrane used was mixed esters of cellulose of $0.5{\mu}m$ pore size and $0.8m^2$ of effective surface area. The methanogenic reactor comprised of UASB (Upflow Anaerobic Sludge Blanket) and AF (Anaerobic Filter). COD removal efficiency was 70~80% and the methane content in the biogas increased up to 90% for the submerged membrane system in the anaerobic reactor. As the cake resistance of membrane caused a serious problem, stainless steal prefilters (40, 53, $63{\mu}m$) and air backwashing methods were applied to minimize the cake resistance effectively. Among the tested prefilters. the $63{\mu}m$ prefilter showed the best performance for reduction of cake resistance and a successful long-tern operation. By cleaning with alkali first and acidic solution later. the permeate flux decreased by long term operation was recovered to 89% of that with a new membrane.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2175-2185
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• 2000

Respiration rate should be a reasonable state variable for the activated sludge and could be used to simulate the performance of the activated sludge process. Toxic materials are classified into three groups, competitive, noncompetitive and uncompetitive. They increase/decrease the half saturation coefficient or specific growth rate. that means decreasing of the substrate removal capacity. In this research, a pilot-scale activated sludge process was operated under extended aeration method, and a representative noncompetitive inhibitor, acidic wastewater was applied to establish a respirometry-based toxicity model. Using this model. the correlation coefficient between measured and calculated respiration rate was 0.96 when acidic wastewater(pH 3.9~5.5) was introduced continuously to the aeration tank. Even though respiration rate was decreased by toxic effect of acidic wastewater, effluent substrate concentration represented to COD was deteriorated just a little bit. It might be caused by the low ratio of readily biodegradable substrate in the input substrate. Reduction of respiration rate by decreasing of input substrate concentration was much lower than that by acidic wastewater, and hence it was estimated that the possibility of false toxic alarm caused by decreasing of substrate concentration should be low.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.3
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• pp.76-85
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• 2004

Anaerobic decomposition of municipal solid waste (MSW) had potential adverse impacts such as the production of methane and long-term post closure on human health and the environment. It was demonstrated that aerobic degradation of MSW resulted in the reduction of a methane yield and the enhancement of stabilization of MSW. Excavated solid wastes were both aerobically and anaerobically treated in order to evaluate the effects of air injection on the stabilization of landfill site. The municipal solid waste (MSW) samples were excavated from a 10-year old landfill (operation period: 1991. 11~1994. 11), Jeonju, Korea. Excavated municipal solid wastes are primarily composed of soils and vinyl/plastics. For the two aerobic simulated lysimeters, the levels of $O_2$ ranged 1.6~23.1% and the levels of $CO_2$ ranged 1.5~15.1%, which confirmed the aerobic decomposition. Aeration did prevent methane formation. For the anaerobic simulated lysimeter, the $CO_2$ rose as $O_2$ was consumed and low levels of CH4 were produced. The pH levels ranged from 7.7 to 8.9 for anaerobic lysimeter and from 7.3 to 8.5 for aerobic lysimeters. As expected, aerobic treatment proved to enhance the removal of biodegradable materials in the excavated solid wastes when monitoring the concentration of BOD, COD, $NH_4-N$, and $NO_3-N$ in the leachate.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.293-298
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• 2005

Lab scale experimental study was carried out for SBR process, to investigate the effects of influent ship sewage organic compound removal and Bacillus sp. state on design parameters. This process was able to remove nitrogen and phosphorus as well as organic matter efficiently. More than 95% of chemical oxygen demand(COD) were removed. In addition, about 97% of total nitrogen (T-N) was reduced. The total phosphorus(T-P) reduction averaged 93%. The performance load of SBR process was shown to be 0.095kg ${\cdot}$ TOC/$m^{3}$ ${\cdot}$ day. The pH was decreased from 8.1 to 7.0 within 30 min and increased to 7.3 at the end of anoxic stage, and these phenomena were explained. The sluge produced in the SBR process is characterized by low generation rate (about 0.36kg ${\cdot}$ MLSS/kg ${\cdot}$ TOC) and excellent settleability. The number of Bacillus sp. in the SBR was 24.2%, indicating that Bacillus sp. was a predominant species in the reactor.

• Applied Chemistry for Engineering
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• v.20 no.1
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• pp.87-93
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• 2009

Pd/activated carbon (Pd/AC) and Pd/alumina (Pd/AO) catalysts were prepared by the impregnation of palladium into activated carbon and alumina. The catalytic characteristics according to the kinds of support materials were compared. The decomposition efficiencies of ozone according to kinds of support materials are about the same when these were compared by adding 10 g of catalysts into the water saturated with ozone. The decomposition efficiencies and the oxidation characteristics (TOC, $COD_{Cr}$) of dichloroacetic acid were compared with the ozone only process and the catalytic ozonations using Pd/activated carbon and Pd/alumina catalysts. The decomposition efficiencies of dichloroacetic acid by catalytic ozonations were better than the one by ozone only process, but there was slight difference of the one between Pd/activated carbon and Pd/alumina catalyst. The decomposition efficiency of dichloroacetic acid was increased with increasing ozone dose at a constant concentration of dichloroacetic acid, but the one was little increased with increasing ozone dose at more than 1.0 L/min of ozone dose. It was seemed that the bicarbonate and the chloric ion formed throughout the decomposition of dichloroacetic acid acted as the scavenger of hydroxyl radical.

• Korean Journal of Environmental Agriculture
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• v.28 no.1
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• pp.47-52
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• 2009

The aim of this study was to evaluate the effect of yeast(Saccharomyces exiguus SJPAF1, referred to as SA) addition on odor emission and contaminants reduction in piggery sluny. Four different rates of yeast addition were compared: no addition(SA0), 0.7L(SA0.7), 1.0L(SA1.0), and 1.5L(SA1.5) to one tone of piggery slurry. Odor emission tended to decrease with increasing the yeast application with concurrent effects of changes in temperature on outside of reactors. Particularly, reduction in ammonia emission was proportional to the yeast application rate; it reduced from 161.1 ppm in SA0 to 47.1 ppm in SA1.5 after 6 days of treatment Decomposition of piggery shiny by yeast increased to 13.8% more in SA1.5, and total amounts of piggery slurry decreased to 12.5% in SA1.5. Total coliforms were detected below 30MPN $ml^{-1}$ in SA1.5, while $8.3{\times}10^3$ MPN $ml^{-1}$ of Total coliforms were found in SA0. However, the effect of yeast addition in piggery slurry seemed to have no influence on the removal efficiency of contaminants such as BOD, COD, $NO_3^{-}-N$, $NH_4^{+}-N$, $PO_4^{-}P$. Consequently, the yeast(Saccharomyces exiguus SJPAF1) addition of 1.5% in the piggery sluny seems to have potential applicability for improving agent of pig-farm environment.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.12
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• pp.682-688
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• 2015

Effect of electrode spacing on the performance of microbial electrolysis cells(MECs) for treating sewage sludge was investigated through lab scale experiment. The reactors were equipped with two pairs of electrodes that have a different electrode spacing (16, 32 mm). Shorter electrode distance improved the overall performance of MEC system. With the 16 mm of electrode distance, the current density was $3.04{\sim}3.74A/m^3$ and methane production was $0.616{\sim}0.804Nm^3/m^3$, which were higher than those obtained with 32 mm of electrode spacing ($1.50{\sim}1.82A/m^3$, $0.529{\sim}0.664Nm^3/m^3$). The COD removal was in the range of 34~40%, and the VSS reduction ranged 32~38%. As the current production increased, VSS reduction and methane production were increased possibly due to the improved bioelectrochemical performance of the system. Methane production was more affected by current density than VSS reduction. These results imply that the reducing the electrode spacing can enhance the methane production and recovery from sewage sludge with the decreased internal resistance, however, it was not able to improve VSS reduction of sewage sludge.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.4
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• pp.91-102
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• 2009

In this study, to estimate the transforming (runoff and leachate) rate of the organic fertilizer made of livestock resources to farm land, laboratory scale test was conducted and the results were obtained as follows: The runoff volume from farm land showed the tendency of increase according to the increase of rainfall intensity. The most rainfall leachated into the underground at the rainfall intensity of 20mm/hr, and rainfall of 5L or less leachated at the rainfall intensity of > 32.4 mm/hr. This shows that surface runoff largely depends on the rainfall intensity when soil characteristic and hardness are similar in each site. When liquid compost was fertilized, the surface runoff was similar with the results from the reactor fertilized by compost, and leachate flow was found to be lower than compost. The runoff ratio of contaminant parameters from farm land were BOD 0.00003,, $COD_{cr}$ 0.00006, TN 0.00056, TP 0.00011, TOC 0.00005, Especially, the runoff ratio of TN showed 10 folds higher than other parameters. On the other hand, the runoff ratio of SS showed higher value of 0.001, and colloid particles of soil caused this result rather than the leachate from compost fertilizer. At all ranges of rainfall intensity, fertilizer removal ratio by farm land was found to be 94.9~98.4% for compost and 85.8~98.1% for liquid compost in terms of BOD. For TN, it resulted in 96.6~98.4% for compost and 97.2~98.5% for liquid compost, and thus the most fertilizer from livestock resources were shown to be reduced through farm land application.

• Korean Journal of Microbiology
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• v.48 no.3
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• pp.192-199
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• 2012

Microalgal biotechnology has gained prominence because of the ability of microalgae to produce value-added products including biodiesel through photosynthesis. However, carbon and nutrient source is often a limiting factor for microalgal growth leading to higher input costs for sufficient biomass production. Use of municipal wastewater as a low cost alternative to grow microalgae as well as to treat the same has been demonstrated in this study using mini raceway open ponds. Municipal wastewater was collected after primary treatment and microalgae indigenous in the wastewater were encouraged to grow in open raceways under optimum conditions. The mean removal efficiencies of TN, TP, COD-$_{Mn}$, $NH_3$-N after 6 days of retention time was 80.18%, 63.56%, 76.34%, and 96.74% respectively. The 18S rRNA gene analysis of the community revealed the presence of Chlorella vulgaris and Scenedesmus obliquus as the dominant microalgae. In addition, 16S rRNA gene analysis demonstrated that Rhodobacter, Luteimonas, Porphyrobacter, Agrobacterium, and Thauera were present along with the microalgae. From these results, it is concluded that microalgae could be used to effectively treat municipal wastewater without aerobic treatment, which incurs additional energy costs. In addition, municipal wastewater shall also serve as an excellent carbon and nitrogen source for microalgal growth. Moreover, the microalgal biomass shall be utilized for commercial purposes.