• Environmental Engineering Research
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• v.21 no.2
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• pp.164-170
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• 2016

Since most of the existing wastewater treatment options lack the ability to treat micro-contaminants, the increased use of pharmaceuticals and personal care products (PPCPs) and release as human waste have become a serious concern in recent years. Constructed wetlands (CWs) are a low-cost technology for wastewater treatment, however, its performance in term of PPCPs removal has not yet been fully investigated. This study aimed to characterize the removal factors and efficiency of acetaminophen (ACT) removal by CWs. The results revealed the decreased concentrations of ACT with increasing hydraulic retention times (HRT) of 0, 3, 5 days. The contribution of removal factors was found to be varied with initial ACT concentration. At the low ACT concentration (i.e. 1 ppb), plant uptake was the dominant, followed by microbial and photolytic removal. In contrast, at the high ACT concentration (i.e. 100 ppb), microbial and photolytic removal were found as dominant factors. On the other hand, hydrogen peroxide ($H_2O_2$) concentration was found at higher level in the plant shoot than in the root probably due to occurrence of the Fenton reaction resulting in PPCPs removal.

• Journal of Korean Society on Water Environment
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• v.25 no.1
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• pp.120-124
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• 2009

This study was performed to investigate the application of submerged membrane bioreactor (MBR) system for biological nutrient removal of municipal wastewater. MBR bioreactor consists of four reactors such as anaerobic, stabilization, anoxic and submerged membrane aerobic reactors with two internal recycles. The hydraulic retention time (HRT), sludge retention time (SRT) and flux were 6.2 hr, 34.1 days and $19.6L/m^2/hr$ (LMH), respectively. As a result of operation, the removal efficiency of $COD_{Cr}$, SS, TN and TP were 94.3%, 99.9%, 69.4%, and 74.6%, respectively. There was no significant effect of microbial activity after the maintenance cleaning using 200 mg/L of NaOCl. Membrane filtration for the treatment of municipal wastewater was performed for longer than 9 months without chemical recovery cleaning.

• Environmental Engineering Research
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• v.24 no.3
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• pp.443-448
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• 2019

The present study was conducted to compare the voltage generation in two-chamber microbial fuel cells (MFCs) with a biocathode where nitrate and oxygen are used as a terminal electron acceptors (TEA) and to investigate the nitrogen removal and the electrochemical characteristics depending on the separators of the MFCs for denitrification. The maximum power density in a biocathode MFC using an anion exchange membrane (AEM) was approximately 40% lower with the use of nitrate as a TEA than when using oxygen. The MFC for denitrification using an AEM allows acetate ($CH_3COO^-$) as a substrate and nitrate ($NO_3{^-}$) as a TEA to be transported to the opposite sides of the chamber through the AEM. Therefore, heterotrophic denitrification and electrochemical denitrification occurred simultaneously at the anode and the cathode, resulting in a higher COD and nitrate removal rate and a lower maximum power density. The MFC for the denitrification using a cation exchange membrane (CEM) does not allow the transport of acetate and nitrate. Therefore, as oxidation of organics and electrochemical denitrification occurred at the anode and at the cathode, respectively, the MFC using a CEM showed a higher coulomb efficiency, a lower COD and nitrate removal rate in comparison with the MFC using an AEM.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.139-139
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• 2022

Nature-based solutions (NBS) involved conservation or rehabilitation of natural ecosystems or the creation of natural processes in modified or artificial ecosystems to mimic natural processes for the improved management of water (UN-Water, 2018). This study investigated the relationship between microbial presence and survival to the pollutant treatment performance of seven different stormwater NBS managing urban stormwater runoff. In this study, seven different stormwater nature-based solution (NBS) was investigated to identify the relationship of microbial community to the pollutant removal performance of stormwater NBS. Based on this study, Proteobacteria was found to be the most dominant microorganism for all stormwater NBS and IS followed by Acidobacteria and Actinobacteria. Acidobacteria, Actinobacteria, Chloroflexi, Gemmatimonadetes, WS3, and AF234118_p were found to have high positive correlation to most pollutant removal efficiency of different stormwater NBS (r-value: 0.62 to 0.68). Using Proteobacteria and Acidobacteria count in stormwater NBS, equations predicting pollutant removal performance were also developed and may be used in minimizing the cost for stormevent monitoring to identify the pollutant removal performance of stormwater NBS.

• KSBB Journal
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• v.16 no.1
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• pp.61-65
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• 2001

In this study, a BTX degrading microbial consortium was obtained from the activated sludges of a BTX releasing sewage water and city sewage water treatment plant. The MY microbial consortium was developed for benzene and toluene degradation, whereas the MA microbial consortium was developed for xylene isomers. The major microorganism of the MA consortium was identified as Rhodococcus ruber DSM 43338T, whereas that of the MY consortium was Rhodococcus sp. In terms of the degradation of a single component, the removal rate of benzene was fastest and decreased in order; toluene, o-xylene, p-xylene and m-xylene. For degradation of mixed BTX, most BTX were degraded within 108 hours and the degradation rate showed either stimulatory or inhibitory effects depending on the composition. MA and MY microbial consortium obtained in this study may be used effectively to remove BTX biologically.

• Journal of Environmental Science International
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• v.11 no.1
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• pp.63-68
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• 2002

In this study, we examined statistical analysis between sewage plant operations parameters and effluent quality We got six components from principle component analysis of the operation parameters and secondary effluent quality. 91.8% of the total variance was explained by the six components. The components were identified in the following order : 1) organic matter removal by aeration basin microbe, 2) settleability on secondary clarifier load, 3) removal of nutrients, 4) microbial number increasement and species diversity, 5) microbial activity in aeration basin, 6) oxidation in aeration basin.

• Journal of Korean Society on Water Environment
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• v.29 no.6
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• pp.782-789
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• 2013

Enhanced biological phosphorus removal (EBPR) behavior and microbial characteristics in the anaerobic-aerobic SBR (PAO SBR) and the anaerobic-anoxic SBR (DPAO SBR) were examined in this research. For 392 days of operation, both SBRs have exhibited a good EBPR (or denitrifying EBPR) performance. $P_{release}/P_{influent}$ ratio was highest in both reactors after the stabilization, while the efficiency of phosphorus removal was decreased since the sludge granulation has been visually observed within the reactor. The comparative analysis of Pyrosequencing-based microbial population between PAO and DPAO sludges showed indirectly that Dechloromonas spp. could utilize $O_2$ and $NO_3{^-}-N$ as an electron acceptor and Accumulibacter phosphatis use only $O_2$ in EBPR system. Also, we concluded that Thauera spp. as a denitrifier contribute significantly to the anoxic phosphorus removal in the DPAO system.

• Journal of Environmental Impact Assessment
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• v.27 no.6
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• pp.595-603
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• 2018

This study was conducted to understand the growth of attached microbial community in small and medium streams of Gyeonggi-do and the removal efficiency of fluoride with changes in growth. The sites monitoring were carried out for 12 weeks at the P1 and P2(P1 is the point where the discharge water flows. P2 is the downstream point of about 2 km flow), and investigated the water quality and the biomass analysis of the attached microbial community. The growth of the attached microbial community increased up to the 7th investigation, and it was observed that detachment phenomenon occurred. Influencing factors about growth of the attached microbial community were flow rate, velocity, and organic material(T-N & T-P). Meanwhile, fluoride content of attached microbial community also tended to increase until the 7th investigation, and decrease from the 8th. It is assumed that fluoride content has also be reduced with the detachment phenomenon of the attached microbial community. It is expected that this will contribute to the evaluation and management of the use of attached microbial community as a means of stream management. The application of techniques using the attached microbial community should include basic investigation of factors that may affect the growth of the attached microbial community and replacement of the attachment plate according to the time of removal.

• Journal of Environmental Science International
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• v.17 no.1
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• pp.97-105
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• 2008

This study examined the contaminated soils with an indicator of TPH using SVE (Soil Vapor Extraction) and biological treatments. Their results are as follows. Water content in the polluted soils slowly decreased from 15% during the initial experimental condition to 10% during the final condition. Purification of polluted soils by Bioventing system is likely to hinder the microbial activity due to decrease of water content. Removal rate of TPH in the upper reaction chamber was a half of initial removal rate at the 25th day of the experiment. The removal rate in the lower reaction chamber was 45% with concentration of 995.4 mg/kg. When the Bioventing is used the removal rate at the 14th day of the experiment was 53%, showing 7 day shortenting. Since the Bioventing method control the microbial activity due to dewatering of the polluted soil, SVE method is likely to be preferable to remove in-situ TPH. The reactor that included microbes and nutrients showed somewhat higher removal rate of TPH than the reactor that included nurtients only during experimental period. In general, the concentration showed two times peaks and then decreased, followed by slight variation of the concentration in low concentration levels. Hence, in contrast to SVE treatment, the biological treatment tend to show continuous repetitive peaks of concentration followed by concentration decrease.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.347-350
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• 2002

The petrochemical products can cause soil and groundwater contamination during their transportation and the use of the products, and while being contained in underground storage tanks(USTs) throughout the leakage. To treat the contaminated soil, the bioventing method is suitable for the remediation of semi-volatile compounds, such as diesel and kerosene. Biofiltration is one of possible method to treat the off-gas produced in the process of the bioventing. This study is related to the usage, effectiveness of treatment, and feasibility of two types of biofilter system made of ceramic-compost and polymer respectively to treat diesel VOCs at constant retention time of 20 sec. Compost biofilter showed the average removal efficiency of 73 % when the inlet concentration increased to 20 ppmv. Increased the inlet concentration decreased the microbial activities as well as the removal efficiency. On the contrary, the removal efficiency of the polyurethane biofilter was maintained at 88 % at the inlet concentration of 13 ppmv during ten days and was obtained to 80 % at the inlet concentration of 30 ppmv in spite of the drop of the efficiency in the sudden increase of the inlet concentration. At the beginning of the experiment it showed low removal efficiency at low inlet concentration due to the low microbial activity, however, as experiments proceed the removal efficiency could be obtained more than 80% at high inlet concentration.