• Journal of Korean Society of Environmental Engineers
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• v.37 no.4
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• pp.228-233
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• 2015

This study was performed to examine the effect of zinc on the biodegradability, nitrification, denitrification and oxygen uptake rate (OUR) using batch reactor and continuous flow stirred tank reactor (CSTR) of anaerobic/anoxic/oxic ($A^2/O$). The results of this study can be summarized as follows. In the case of the effect of zinc on organic treatment, zinc had no effect up to 12 mg/L with batch reactor but biodegradability was lowered when it was above 3.0 mg/L with CSTR. Concerning the case on nitrification and removal of nitrogen, nitrification rate was lowered when zinc was above 6.0 mg/L with batch reactor and removal rate of nitrogen was lowered when zinc was above 3.0 mg/L with CSTR. Removal rate of phosphorus was lowered when it was above 6.0 mg/L zinc with batch reactor and above 3.0 mg/L zinc with CSTR. In the case of OUR, it decreased as microbial activity was affected when zinc concentration was above 3.0 mg/L in CSTR.

• Journal of Korean Society on Water Environment
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• v.36 no.6
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• pp.581-591
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• 2020

In this study, two types of reactors were operated to examine the properties of methanol uptake under the high-rate denitrification process. In a sequencing batch reactor, the denitrifying activity was enriched up to 0.80 g-N/g-VSS-day for 72 days. Then, the enriched denitrifying sludge was transferred to a completely stirred tank reactor (CSTR). At the final phase on Day 46-50, the nitrogen removal efficiency was around 100% and the total nitrogen removal rate reached 0.097±0.003 kg-N/㎥-day. During the continuous process, the sludge settling index (SVI30) was stabilized as 118.3 mL/g with the biomass concentration of 1,607 mg/L. The continuous denitrifying process was accelerated by using a sequencing batch reactor (SBR) with a total nitrogen removal rate of 0.403±0.029 kg-N/㎥-day with a high biomass concentration of 8,433 mg-VSS/L. Because the reactor was open to ambient air with the dissolved oxygen range of 0.2-0.5 mg-O2/L, an increased organic carbon requirement of 5.58±0.70 COD/NO3--N was shown for the SBR in comparison to the value of 4.13±0.94 for the test of the same biomass in a completely anaerobic batch reactor. The molecular analysis based on the 16S rRNA gene showed that Methyloversatilis discipulorum and Hyphomicrobium zavarzinii were the responsible denitrifiers with the sole organic carbon source of methanol.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.1
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• pp.34-39
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• 2005

Trichloroethylene (TCE) is an environmental contaminant provoking genetic mutation and damages to liver and central nerve system even at low concentrations. A practical scheme is reported using toluene as a primary substrate to revitalize the biofilter column for an extended period of TCE degradation. The rate of trichloroethylene (TCE) degradation by Pseudomonas putida F1 at $25^{\circ}C$ decreased exponentially with time, without toluene feeding to a biofilter column ($11\;cm\;I.D.{\times}95\;cm$ height). The rate of decrease was 2.5 times faster at a TCE concentration of $970\;{\mu}g/L$ compared to a TCE concentration of $110\;{\mu}g/L$. The TCE itself was not toxic to the cells, but the metabolic intermediates of the TCE degradation were apparently responsible for the decrease in the TCE degradation rate. A short-term (2 h) supply of toluene ($2,200\;{\mu}g/L$) at an empty bed residence time (EBRT) of 6.4 min recovered the relative column activity by $43\%$ when the TCE removal efficiency at the time of toluene feeding was $58\%$. The recovery of the TCE removal efficiency increased at higher incoming toluene concentrations and longer toluene supply durations according to the Monod type of kinetic expressions. A longer duration ($1.4{\sim}2.4$ times) of toluene supply increased the recovery of the TCE removal efficiency by $20\%$ for the same toluene load.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.6
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• pp.577-585
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• 2014

A series of experiments using atmospheric-pressure non-thermal plasma coupled with transition metal catalysts were performed to remove ethylene from agricultural storage facilities. The non-thermal plasma was created by dielectric barrier discharge, which was in direct contact with the catalyst pellets. The transition metals such as Ag and $V_2O_5$ were supported on ${\gamma}-Al_2O_3$. The effect of catalyst type, specific input energy (SIE) and oxygen content on the removal of ethylene was examined to understand the behavior of the hybrid plasma-catalytic reactor system. With the other parameters kept constant, the plasma-catalytic activity for the removal of ethylene was in order of $V_2O_5/{\gamma}-Al_2O_3$ > $Ag/{\gamma}-Al_2O_3$ > ${\gamma}-Al_2O_3$ from high to low. Interestingly, the rate of plasma-catalytic ozone generation was in order of $V_2O_5/{\gamma}-Al_2O_3$ > ${\gamma}-Al_2O_3$ > $Ag/{\gamma}-Al_2O_3$, implying that the catalyst activation mechanisms by plasma are different for different catalysts. The results obtained by varying the oxygen content indicated that nitrogen-derived reactive species dominated the removal of ethylene under oxygen-lean condition, while ozone and oxygen atoms were mainly involved in the removal under oxygen-rich condition. When the plasma was coupled with $V_2O_5/{\gamma}-Al_2O_3$, nearly complete removal of ethylene was achieved at oxygen contents higher than 5% by volume (inlet ethylene: 250 ppm; gas flow rate: $1.0Lmin^{-1}$; SIE: ${\sim}355JL^{-1}$).

• Journal of Environmental Health Sciences
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• v.40 no.2
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• pp.127-136
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• 2014

Objectives: This study was conducted to investigate the removal of high odor concentration from swine wastewater treatment facility by full scale biofilter using liquid with deodorant mixed with earthworm cast and distillery sludge. Methods: The supply of the culture liquid to the microorganism on the media in the biofilter increases the activity and growth of biomass. The experimental equipment was biofilter tower with treatment capacity of 90 m 3/min. The experimental conditions included gas flow of $60m^3/min$, retention time of 20 sec, and gas/liquid ratio of 67. Results: With changing season from winter to summer, the inlet odor concentration of ammonia increased from 2.5 ppm to 29 ppm, and of hydrogen sulfide from 21 ppm to 91 ppm, respectively. The odor treatment system with biofilter using the culture liquid was stable when the high loading rate increased and showed excellent removal grade with an average of 96.7% for ammonia, and an average of 93.7% for hydrogen sulfide. The pH and SCOD in the recirculating culture liquid near the bottom of the biofilter tower decreased with operation time, but its influence on the odor removal rate was negligible, because the organic matter (SCOD) was replaced by some culture liquid supplied 2-4 times per day. Conclusions: The biofilter using culture liquid could successfully remove high odor concentration which was generated from swine wastewater treatment facility.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.1
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• pp.89-96
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• 1994

The recovery posibility of granular sludge inactivated due to high organic loading at stawrt-up stage of UASB reactors was examined at various storage periods while kept at a constant temperature of $35^{\circ}C$. It was noticed that the inactivated sludge kept without feeding recovered microbial activity much faster than that kept with continuous feeding. The activity of the sludge gradually recovered to the point where the organic removal rate of 0.15g of 0.15g COD/g VSS-day at the inactivated stage had changed to 0.36g COD/g VSS-day after 60 days of storage without feeding, which was similar to the active granular sludge activity of 0.38g COD/g VSS-day. There was no significant different in the characteristics of activity recovery between granular sludge and smashed sludge.

• Journal of Environmental Health Sciences
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• v.28 no.5
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• pp.35-41
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• 2002

This study was conducted to evaluate the effect of initial concentration on pilot-scale composting of diesel-con-laminated soil. Sandy soi] was used in this study. Target contaminant, diesel oil, was spiked. at about 10,000, 25,000, and 50,000 mg TPH/kg of dry roil. Mit ratio of soil to sludge was 1:0.5 as wet weight basis. Removal efficiencies for initial concentrations of 12,966,23,894 and 51,042 mg TPH/kg were 90, 93 and 54％, respectively, during 33 days of composting. Normal alkanes in TPH ranged from 15 to 22％ in initial soils. Volatilization of individual normal alkane in 1,999 mg n-alkanes/kgwas completed within 4 days, while n-alkane compounds of Cl1-Cl4 in 5,270 and 9,836 mg n-alkanes/kg were volatilized continuously during 33 days of composing operation. The first order degradation rate con-stants for 12,966, 23,894, and 51,042 mg TPH/kg were 0.058, 0.076, and 0.022/day, and those for 1,997 5,270, and 9,836 mg n-alkanes/kg were 0.093, 0.100, and 0.019/day, respectively. Considering TPH removal rate, $CO_2$porduction rate, and dehydrogenase activity, the concentration of 51,042 mg TPH/kg inhibited biodegradation of diesel-composting.

• Journal of Environmental Health Sciences
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• v.26 no.2
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• pp.59-66
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• 2000

Effects of carbon dioxide partial pressure(PCO2) on bacterial population, methane production rate and matter degradation in anaerobic digestion were investigated by using anaerobic chemostat type reactors at 35$\pm$1$^{\circ}C$, at the HRT of 7 days. At PCO2 of 0.5 atm, the specific methane production rate and specific substrate removal rate reached the maximum rates. The methane production rates in the reactors fed by mixed substrate were 26% higher than those obtained under the controlled condition. The number of acetate consuming methanogenic bacteria enumerated by the MPN(most probable number) method, decreased when PCO2 exceeded 0.7 atm. Hydrogen consuming methanogenic bacteria and homoacetogenic bacteria increased as PCO2 increased from 0.1 to 0.6 atm, however, decreased slightly at PCO2 above 0.7 atm. The number of hydrolytic bacteria, sulfate-reducing bacteria and H2-producing acetogenic bacterial were not much influenced by the change of PCO2. The potential methanogenic activity reached the maximum at PCO2 0.5 atm, however, decreased significantly when PCO2 exceeded 0.7 atm, would depend on free PCO2 concentration in solution.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6B
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• pp.689-694
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• 2006

The system performance of a bioactive foam reactor (BFR), that consists of a foam column using a surfactant and a biodegradation basin containing suspended bacteria, was investigated for the treatment of gaseous toluene or a mixture of four volatile organic compounds (VOCs, benzene, toluene, p-xylene, and styrene). Overall, the BFR achieved stable VOC removal efficiencies, indicating that it can be used as a potential alternative over conventional packed-bed biofilters. Furthermore, a dynamic loading test showed that relatively constant removal was maintained at the elevated loading due to a high mass transfer rate in the foam column. However, as the inlet concentration of VOCs increased, a portion of the VOCs mass-transferred to the liquid phase was stripped out from the biodegradation basin, resulting in a decrease in the overall removal efficiency. In the BFR, the removal efficiency of the individual VOC was mainly determined depending on the biodegradation rate (styrene > toluene > benzene > p-xylene), rather than the mass transfer rate. Consequently, increases in the microbial activity and the volume of the basin could improve the overall performance of the BFR system. Further investigation on microbial activity and community dynamics is required for the BFR when subjected to high loadings of VOC mixtures.

• Journal of Microbiology and Biotechnology
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• v.18 no.11
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• pp.1809-1818
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• 2008

Biotechnological treatment of sulfate- and metal-ions-containing acidic wastewaters from mining and metallurgical activities utilizes sulfate-reducing bacteria to produce sulfide that can subsequently precipitate metal ions. Reducing sulfate at a low pH has several advantages above neutrophilic sulfate reduction. This study describes the effect of sulfide removal on the reactor performance and microbial community in a high-rate sulfidogenic gas-lift bioreactor fed with hydrogen at a controlled internal pH of 5. Under sulfide removal conditions, 99% of the sulfate was converted at a hydraulic retention time of 24 h, reaching a volumetric activity as high as 51 mmol sulfate/l/d. Under nonsulfide removal conditions, <25% of the sulfate was converted at a hydraulic retention time of 24 h reaching volumetric activities of <13 mmol sulfate/l/d. The absence of sulfide removal at a hydraulic retention time of 24 h resulted in an average $H_2S$ concentration of 18.2 mM (584 mg S/I). The incomplete sulfate removal was probably due to sulfide inhibition. Molecular phylogenetic analysis identified 11 separate 16S rRNA bands under sulfide stripping conditions, whereas under nonsulfide removal conditions only 4 separate 16S rRNA bands were found. This shows that a less diverse population was found in the presence of a high sulfide concentration.