• Journal of Korean Society on Water Environment
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• v.23 no.6
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• pp.906-912
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• 2007

A lab-scale thermophilic aerobic digestion (TAD) system was operated at $64^{\circ}C$ with mixed primary and secondary sludges taken from a large wastewater treatment plant. The semi-continuously operated reactor at HRTs of 1, 3 and 6 days indicated that longer HRT could stabilize sludge organics and solids comparable to anaerobic digestion. It has been found that reduced HRT of 3 and 1 day produced the effluent with highly biodegradable soluble organics, indicating the possibility of energy recovery in TAD. No proof of biological nitrification was observed at thermophilic operating temperature of $64^{\circ}C$, while nitrogen removal seemed due to nitrogen exertion during the aerobic thermophilic cell synthesis as well as ammonia stripping.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.3
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• pp.124-130
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• 1997

Wastewater containing phenol was treated using Pseudomonas sp. B3 in continuous reactor, reaction characteristics and kinetics according to variation of volumetric loading rate in continuous reactor were studied. The removal efficiencies of phenol were more than 99% at the whole range of experiment, and those of COD were 97% at the volumetric loading rate, $0.96kg/m^3{\cdot}d$ and 88% at $3.0kg/m^3{\cdot}d$, respectively. Kinetics constants of $q_m$, $K_s$, Y and $K_d$ were obtained 0.901 l/d, 0.620mg/l, 0.659 and 0.219 l/d, respectively. As compared with to constants of standard activated sludge process, these constants were remarkably different because of toxicity and inhibition of phenol to microbes. And also, kinetics constants of oxygen utilization, a, and b, were shown 0.384 kg $O_2/kg$ phenol and 0.029 l/d.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.3
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• pp.29-35
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• 1999

The purpose of this study is to remove the organics, nitrogen and phosphorus using biosorption for the domestic sewage. The new process using biosorption is based on the methods of contact-stabilization, which remove the organics by absorbing them to the surface of the microorganism in the activated sludge. This process consists of biosorption reactor, biosorption clarifier, nitrifying reactor, nitrifying clarifier, denitrifying reactor, phosphorus uptake(polishing) reactor and final clarifier. The efficiency of removal could be reached 91% for organics, 76% for nitrogen, 90% for phosphorus in Eujungbu pilot plant. We operated the plant which irrigated $10m^3$ per day for sewage. During our operation the HRT(Hydraulic Retention time) was maintained for 10.5hr, but it could be reduced as 8.5hr according to our operation results.

• Textile Coloration and Finishing
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• v.17 no.2 s.81
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• pp.31-39
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• 2005

This study was conducted to remove the dyes in dye wastewater by the chemical precipitation or biological treatment which are one of the main pollutants in dye wastewater. In order to remove the disperse dyes effectively in aqueous solution by chemical precipitation process, coagulation and flocculation tests were carried out using several coagulants on various reaction conditions. It was found that the Ferrous sulfate was the most effective coagulant for the removal of disperse dye(DB79), and we could get the best result for the removal of disperse dye(DB56) in the aspects of TOC removal efficiency and sludge yield. When the Ferrous sulfate dosage was 800mg/l, the sludge settling velocity was very fast$(SV_{30}=4\%)$, and the color was effectively removed in the disperse dye(DB79) solution. Although the color removal was ineffective when the Alum was used as a coagulant, the sludge yield decreased in comparison with the Ferrous sulfate or the Ferric sulfate being used in the disperse dye(DB56) solution. In order to decolorize disperse dye(DR17) by using biological treatment process, a strain which has potential ability to degrade disperse dyes was isolated from natural system. The optimal culture conditions of temperature and pH were found to be $40^{\circ}C\;and\;8.5\~9$, respectively. When yeast extract was mixed with polypeptone at the mixing ratio of 1:1 as a nitrogen source, decolorization efficiency was highest$(93\%)$ among the nitrogen sources. The strain screened was excellent to adjust to pH, and it seems to have ability to control pH needed to growth. The optimal culture conditions in concentration of $MgSO_{4.}\cdot7H_2O\;and\;KH_2PO_4$ were $0.1\%(w/v)\;and\;0.2\%(w/v)$, respectively. Strains degrading and decolorizing reactive dyes, RB198 and RR141 which were isolated from water system, are named RBK1 and RRK. And the cell growth characteristics of RBK1 and RRK were investigated. The optimal culture conditions of temperature and pH were found to be 30t' and 7.0, respectively. Optimum nitrogen source was peptone, and it was found that decolorization efficiencies by strains RBK1 and RRK, were $85\%\;and\;62\%$, respectively, with introduction of 4,000mg/l of peptone. In the case of RBK1, color removal efficiencies were very high below 400mg/l. Decolorization efficiency was over $90\%$ at 20hours of culture time. The Color degradation ability of RRK was lower than that of RBK1.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.5
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• pp.326-334
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• 2012

To determine the concentrations and the mass flow of selected 10 perfluorinated compounds (PFCs), a field study was conducted in a wastewater treatment plant. Raw influent, primary influent, primary effluent, aeration tank effluent, secondary effluent, final effluent, dehydration liquor, primary sludge, thickened sludge, final sludge were collected over 3 days in the summer and the winter respectively. Collected samples were equally mixed and then served as an analytical sample. Total 10 compounds were analyzed. In terms of treated water, the concentration of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) were in range of N.D.~26.29 ng/L and N.D.~38.15 ng/L respectively. Perfluorononanoate (PFNA) and perfluorohexanesulfonate (PFHxS) were ranged from N.D. to 36.79 ng/L and from N.D. to 24.36 ng/L. In terms of sludges, a concentration of PFOS, PFOA, and perfluorodecanesulfonate (PFDS) were detected from 6.82 to 59.37 ng/g, from 0.13 to 0.37 ng/g, from N.D. to 0.83 ng/g respectively. Mass loading for PFCs increased during wastewater treatment except for PFNA. The observed increase in mass flow of PFCs may have resulted from biodegradation of precursor compounds.

• Membrane Journal
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• v.27 no.5
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• pp.375-388
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• 2017

Wastewater treatment (WWT) technology has been developing from simple pollutant treatment to energy and resource-saving advanced technology, and various technologies combined with IT and BT are developed to minimize the amount of pollutant and toxic substance discharge to the public water areas and to improve operational efficiency. To examine the development trend of domestic wastewater treatment technology, the registered patent technologies were surveyed, classified and analyzed by year and sector. This paper considers the status of patent registration related to WWT from 2010.1 to 2017.5 in terms of the number of specific technical areas, and the trends are analyzed based on the 10 categorization field such as biological and physicochemical treatment process, equipment and device, material, sludge treatment, membrane, process control and 42 specific technical areas. A total of 3,356 patents have been registered since 2010, and the number of patents has been decreasing since the peak at 2013 and maintains 3~400 per year. The total number of patents has not yet been less than other countries, but the number of patents of more advanced technologies, which can lead the global market, such as process monitoring, new concept processing and equipment technologies is still insufficient compared to developed countries.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.5
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• pp.367-377
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• 2019

In this study, the fate and removal of 15 pharmaceuticals (including stimulants, non-steroidal anti-inflammatory drugs, antibiotics, etc.) in unit processes of a sewage treatment plant (STP) were investigated. Mass loads of pharmaceuticals were 2,598 g/d in the influent, 2,745 g/d in the primary effluent, 143 g/d in the secondary effluent, and 134 g/d in the effluent. The mass loads were reduced by 95% in the biological treatment process, but total phosphorous treatment did not show a significant effect on the removal of most pharmaceuticals. Also, mass balance analysis was performed to evaluate removal characteristics of pharmaceuticals in the biological treatment process. Acetaminophen, caffeine, acetylsalicylic acid, cefradine, and naproxen were efficiently removed in the biological treatment process mainly due to biodegradation. Removal efficiencies of gemfibrozil, ofloxacin, and ciprofloxacin were not high, but their removal was related to sorption onto sludge. This study provides useful information on understanding removal characteristics of pharmaceuticals in unit processes in the STP.

• Korean Journal of Environmental Agriculture
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• v.33 no.2
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• pp.78-85
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• 2014

BACKGROUND: Recent studies using various industrial wastes for heavy metal stabilization in soil were conducted in order to find out new alternative amendments. The acid mine drainage sludge(AMDS) contains lots of metal oxides(hydroxides) that may be useful for heavy metal stabilization not only waste water treatment but also soil remediation. The aim of this study was to investigate the applicability of acid mine drainage sludge for heavy metals stabilization in soils METHODS AND RESULTS: Alkali soil contaminated with heavy metals was collected from the agricultural soils affected by the abandoned mine sites nearby. Three different amounts(1%, 3%, 5%) of AMDS were applied into control soil and contaminated soil. For determining the changes in the extractable heavy metals, $CaCl_2$ and Mehlich-3 were applied as chemical assessments for metal stabilization. For biological assessments, lettuce(Lactuca sativa L.) and chinese cabbage(Brassica rapa var. glabra) were cultivated and accumulation of heavy metals on each plant were determined. It was revealed that AMDS reduced heavy metal mobility and bioavailability in soil, which resulted in the decreases in the accumulation of As, Cd, Cu, Pb, and Zn in each plant. CONCLUSION: Though the high level of heavy metal concentrations in AMDS, any considerable increase in the heavy metal availability was not observed with control and contaminated soil. In conclusion, these results indicated that AMDS could be applied to heavy metal contaminated soil as an alternative amendments for reducing heavy metal mobility and bioavailability.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.6
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• pp.893-906
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• 2011

The effect of ultrasound pretreatment on sludge degragability was investigated at different condotions: ultrasonic frequency(28, 40, 50kHz), intensity(10, 25, 50W), sonication time(10, 20, 30, 60min). Total suspended solid(TSS) and soluble chemical oxygen demand(SCOD) concentration were measured for the evaluation of pretreatment efficiency. The pretreated sludge was used as the feedstock for anaerobic digestion process. Biogas production and volatile suspended solid(VSS) removal were determined for evaluating the process performance. 1. TSS concentration of the sludge decreased at a constant rate as sonication operation was applied. The degradation rate of TSS increased when ultrasound frequency was decreased from 50kHz to 28kHz and intensity was increased from 10W to 50W. Efficiency of TSS degradation per input energy increased as ultrasonic frequency and intensity were decreased. At the frequency of 28 and 40kHz, SCOD concentration rapidly increased during the initial 30min of sonication time, and then it gradually increased. At 50kHz, SCOD concentration constantly increased for 60min of the sonication time. The SCOD production rate increased with increasing intensity under all ultrasound frequencies. 2. The optimum condition of ultrasound treatment was 28kHz, 50W and 60min for maximizing the biogas production, methane fraction, VSS removal. The highest values in biogas production, methane fraction in biogas, VSS removal were 370ml, 70%, 2.45g, respectively. Methane production rate per input energy increased at ultrasonic frequency and intensity decreased. 3. When raw sludge was pretreated at the condition of ultrasonic frequency of 28 and 40kHz in series, sequential-frequency sonication, intensity of 50W and 60min, biogas production, methane fraction, VSS removal were about the same that of 28kHz single-frequency sonication. When sequential-frequency sonication of 28 and 50kHz was applied in series, biogas production, methane fraction, VSS removal were 356 ~ 423ml, 69 ~ 71%, 2.41 ~ 2.78g, respectively. The pretreatment efficiency of 28-50kHz sequential-frequency sonication which sonication time of 28kHz and 50kHz was 40min and 20min was higher than that of 28kHz single-frequency sonication.

• Journal of Life Science
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• v.21 no.3
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• pp.444-450
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• 2011

Perchlorate ($ClO_4^-$) is a contaminant found in surface water and soil/ground water. Autotrophic perchlorate-reducing bacteria (PRB) use hydrogen gas ($H_2$) as an electron donor to remove perchlorate. Since iron corrosion can produce $H_2$, feasibility of autotrophic perchlorate-removal using zero-valent iron (ZVI) was examined in this study using activated sludge that is easily available from a wastewater treatment plant. Batch test showed that activated sludge microorganisms could successfully degrade perchlorate in the presence of ZVI. The perchlorate biodegradation was confirmed by molar yield of $Cl^-$ as perchlorate was degraded. Scanning electron microscope revealed that rod-shaped microorganisms on the surface of iron particles used for the autotrophic perchlorate-removal, suggesting that iron particles could serve as supporting media for the formation of biofilm as well. DGGE analyses revealed that microbial profile of the inoculum (activated sludge) was different from that of biofilm sample obtained from the ZVI-added enrichment culture used for $ClO_4^-$-degradation. A major band of the biofilm sample was most closely related to the class Clostridia.