• Magazine of the Korean Society of Agricultural Engineers
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• v.32 no.3
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• pp.102-115
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• 1990

Importance of anaerobic digestion as an energy generating device has been increased as fuel shortage becomes serieous. Several modification methods on the conventional digesters including Powdered Activated Carbon (PAC) addition and two-phase digestion were studied to enhance the gas production. This study investigated the effects of PAC on anaerobic digestion of chicken manure in terms of gas production and sludge stabilization. As a first experiment, an optimum PAC dose for efficient gas production was determined in a batch test. In semi-continuous experiments, an optimum Sludge Retention Time (SRT) at that PAC concentration and an overall substate utilization rate coefficient were investigated. A portion of gas increased by PAC addition was estimated using a substrate utilization rate coefficient of microorganisms attached on PAC. This test was performed in batch experiments using acetic acid as a substrate. The digesters for all experiments were kept 35${\pm}$ 1˚C in a heated water bath. Mixing was performed manually once a day and the produced gas was collected for daily reading. The following conclusions were made for this study. 1. Cptimum PAC concentration was 5% total solids, where gas production rate was increased by 20 percents. 2. Optimum SRT was 7.5 days. 3. Substrate utilization rate coefficient of microorganisms attached on PAC was about twice as much as that of suspended ones.

• Journal of the Korean Applied Science and Technology
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• v.9 no.2
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• pp.165-174
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• 1992

The standardized activated sludge for the biodegradation test of anion surfactants has been produced from the collected microorganisms in the soil and the wastewaters treatment plant. The activated sludge was kept under control of the pH, dissolved oxygen, microorganisms and inoculated the basal medium flasks with LAS and LAS mixed with heavy metals [Cd(II), Cu(II), Zn(II)]. Based of results, the inhibition effect(%) of heavy metals in LAS biodegradation were 1. All 1% when LAS 30mg/l-Cd(II), Cu(II) and Zn(II) 0.1mg/l, respectively 2. All 1${\sim}$10% when LAS 30mg/l-Cd(II), Cu(II) and Zn(II) 1mg/l, respectively 3. All 10${\sim}$40% when LAS 30mg/l-Cd(II), Cu(II) and Zn(II) 10mg/l, respectively 4. All 30${\sim}$65% when LAS 30mg/l-Cd(II), Cu(II) and Zn(II) 100mg/l, respectively And toxicity order of heavy metals to the microorganisms in LAS biodegradation were Cd>Cu>Zn in low concentration(0.1${\sim}$1mg/l)and Cd>Zn>Cu in high concentration(10${\sim}$100mg/l).

• Environmental Engineering Research
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• v.25 no.1
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• pp.80-87
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• 2020

Landfill waste decomposition generates a dark effluent named, leachate which is characterized by high organic matter content. To minimize these polluting effects, it becomes necessary to develop an effective landfill leachate treatment process. The objective of this study was to evaluate the performance of an innovative approach based on air stripping, anaerobic digestion (AD) and aerobic activated sludge treatment. A reduction of 80% of ammonia and an increase of carbon to nitrogen ratio to 25 were obtained, which is a suitable ratio for AD. This latter AD was performed in fixed bed reactor with progressive loading rate that reached 2 and 3.2 g COD/L/d for the raw and diluted leachate (1:2), respectively. The anaerobic treatment led to significant removal of chemical oxygen demand (COD) and biogas production, especially for the diluted leachate. The COD removal was of 78% for the raw leachate and a biogas production of 4 L/d with 70% methane content. The use of the diluted leachate led to 81% of COD removal and 7 L/d biogas with 75% methane content. It allowed a removal of 77% COD and more than 97% of the organic compounds present in the initial leachate sample.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.2
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• pp.137-145
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• 1990

In this research, biological uptake of heavy metals(Cd(II), Cu(II), Zn(II)) was measured under various conditions ; pH, initial heavy metal concentration, temperature, contact time and the amount of biomass through batch test. From this research, it was found that heavy metals might be removed through adsorption and accumulation in activated sludge process. Heavy metals were highly concentrated by microbial floc in activated sludge. Also, the removal efficiency was reached up to 80~90% within and after 1 hour the increase of removal efficiency was minimal. The order of accumulation efficiency was Cu(II)>Zn(II)>Cd(II), and the bonding strength between heavy metals and microbial floc may be expressed in order of Cu(II)>Zn(II)>Cd(II).

• Journal of Microbiology
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• v.40 no.3
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• pp.193-198
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• 2002

Several 2,4,6-trinitrotoluene (TNT) degrading bacteria were isolated from an activated sludge by an enrichment culture technique, and their TNT removal activities were examined. Among the isolates, strain C1 showed the highest degrading capability, and completely removed 100 or 200 mg I$\^$-1/ of TNT within 6 hours of incubation. This bacterium was identified as Klebsiella sp. The effects of different carbon sources on the removal of the parent TNT by Klebsiella sp. C1 were negligible, but the transformation rates of TNT metabolites such as amino-dinitrotoluenes and diamino-nitrotoluenes were higher with fructose addition compared to glucose addition. When nitrate was used as the nitrogen source, the degradation rates of TNT and hydroxylamino-dinitrotoluenes were higher than those with the ammonium addition. Although the TNT removal rate of Klebsiella sp. C1 was slightly higher in anaerobic conditions, the further transformations of TNT metabolites were more favorable in aerobic conditions.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.4
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• pp.119-126
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• 1996

Influence factors and efficiency characteristics for treatment of wastewater containing phenol were studied with using Pseudomonas sp. B3. It took 130 hours to remove phenol, when only activated sludge of terminal disposal palnt of sewage was innoculated in batch culture, but it was required just 36 hours, when bacteria degrading phenol and activated sludge were simultaneously innoculated. If only phenol an carbon source was used, it necessary 36 hours for biodegradation of phenol, while glucose was added to medium, it took 73 hours. It was revealed as excellent effluent and SVI, when the F/M ratio, COD and phenol concentration were 53mg/l and 1.2mg/l, respectively, and optimum F/M ratio was revealed 0.31. The reactor were seriously shocked as reducing hydraulic retention time at constant phenol concentration more than increasing phenol concentration at constant hydraulic retention time, when volumetric loading rate was increased to $0.8kg\;phenol/m^3{\codt}d$ from $1.6kg\;phenol/m^3{\codt}d$. And also the effluent phenol concentration was 34mg/l after starting 12 hours of shocking and reactor was recovered as steady state after 65 hours of changing in the former test. Although the effluent phenol concentration was maximum value with 12mg/l after starting 20 hours of shocking and reactor was recovered as steady state after 54 hours of changing in the later test.

• Journal of Korean Society on Water Environment
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• v.26 no.1
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• pp.96-103
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• 2010

In this work, the presence of nitrification biochemical oxygen demand (NBOD) frequently occurred in the sewer outflow in winter season was analysed by the COD fraction methods using the respirometry and process simulations with real operation data measurements and analysis. The activated sludge models applied in this process simulation were based on the ASM No.2d temp. models, published by International Association on Water Quality (IAWQ). The ASM No.2d model is an extension of the ASM No.2 model and takes into account of carbon removal, nitrification, denitrification and phosphorus removal. The denitrifying capacity of phosphorus accumulating organisms has been implemented in the ASM No.2d model because experimental evidence shows that some of the phosphorus accumulating organisms can denitrify. It was shown that the concentrations of autotrophs (X_AUT) in the secondary clarifier and the $NH_4-N$ of T-N increased in the presence of NBOD measurements. Because of the low temperature (average $8^{\circ}C$) and possible operational troubles, the outcoming autotrophs exhausted oxygen in the process of nitrifying $NH_4-N$.

• Journal of Environmental Science International
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• v.11 no.3
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• pp.177-182
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• 2002

A biosurfactant-producing microorganism was isolated from activated sludge by enrichment culture when grown on a minimal salt medium containing n-hexadecane as a sole carbon source. This microorganism was identified as Pseudomonas sp. and it was named Pseudomonas sp. EL-G527. It's optimal culture condition is 2% n-hexadecane, 0.2% NH$_4$NO$_3$, 0.3% KH$_2$PO$_4$, 0.3% $K_2$HPO$_4$, 0.02% MgSO$_4$ㆍ7$H_2O$, 0.0025% CaCk$_2$ㆍ6$H_2O$, 0.0015% FeSO$_4$ㆍ7$H_2O$ in 1$\ell$ distilled water and initial pH 7.0. Cultivation was initiated with a 2% inoculum obtained from starter cultures grown in 30 $m\ell$ of the same medium in 250 $m\ell$ flask. They were cultivated at 3$0^{\circ}C$ in reciprocal shaking incubator and the highest biosurfactant production was observed after 4 days.

• Journal of the Korean Society of Clothing and Textiles
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• v.28 no.8
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• pp.1048-1056
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• 2004

Hydrophilicities of finished cotton fabrics were evaluated in respect of moisture regain and wickability. Changes in internal structure were determined using X-ray diffraction and surface changes in degraded samples were observed through a microscopy. Activated sludge test, soil burial test and enzyme hydrolysis were employed to evaluate the biodegradabilities. In addition, correlation analysis was done between biodegradability and the factors affecting biodegradability in each evalution methods. It was shown that hydrophilicities of silicone finished specimens were lower than that of untreated cotton and decreased in a row of PDMS(polydimethyl siloxane : -CH$_3$)＞AFS(amino functional siloxane ; -C$_3$H$_{6}$ NHC$_2$H$_4$NH$_2$)＞MHPS(methylhydrogen polysiloxane : -H, Cat : (C$_{17}$ H$_{35}$ COO)$_2$Zn) Although, moisture regain of mercerized cotton was higher than those of the others, wickability was shown to be lower. It was represented that crystalinities of cotton fabrics decreased by the silicone treatment. In activated sludge test and soil burial test, biodegradabilities of silicone treated specimens were lower than that of untreated cotton, where specimens of higher biodegradability exhibited higher biodegradability except mercerized ones. The results from enzyme hydrolysis, however, showed somewhat different tendency in that biodegradability was more closely related with the crystallinities of fabrics. It can be thought that enzyme hydrolysis is carried out for short time, physical accessibility becomes important.

• Korean Journal of Environmental Biology
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• v.22 no.3
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• pp.400-404
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• 2004

Polycaprolactone (PCL), a synthetic aliphatic polyester, was buried in activated sludge soil for 66 days at $27^\circ{C}$ and $37^\circ{C}$. The morphology of the surface of PCL film degraded by soil microorganisms was observed. Soil microorganisms degrading PCL were isolated and identified. Soil fungi and soil bacteria utilizing PCL as carbon or energy source were identified as Paecilomyces fumosoroseus KH27, Penicillium digitatum KH28, Fusarium solani KH29, Aspergillus sp. KH30 and Ochrobactrum anthropi KH31, respectively. Biodegradation test of PCL by the isolated strains showed that, P. digitatum KH28 exhibited the most PCL degrading activity at $27^\circ{C}$. However, at $37^\circ{C}$ O. anthropi KH31 showed higher degrading activity than the other soil microorganisms tested.