• Journal of Korean Society of Environmental Engineers
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• v.28 no.10
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• pp.1090-1097
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• 2006

The anoxic activated sludge process was applied to the treatment of industrial box-mill wastewater, which exhibited the high removal efficiencies of $90{\sim}94%$$ TCOD_{Mn}$ and $58{\sim}81%$ Color. For the design of industrial anoxic activated sludge process, Monod bio-kinetic coefficients of box-mill wastewater were estimated as follows: $K_{max}$(maximum specific substrate removal rate)=0.52 $day^{-1}$, $K_s$(half saturation constant)=314 mg/L, $K_d$(decay coefficient)=0.274 $day^{-1}$, y(microbial yield coefficient)=0.908 mg/mg, and ${\mu}_{max}$(maximum specific growth rate)=0.472 $day^{-1}$. Space loading factors for the design analysis were practically determined as the values of F/M ratio=$0.043{\sim}0.07$ kg-$TCOD_{Mn}$/kg-SS-day, BOD space loading=$0.18{\sim}0.3$ kg-$TCOD_{Mn}/m^3-day$, and ${\theta}_x=6.8{\sim}26.4$ day when considering the relationship of these loading factors with growth dynamics of microorganisms, the F/M ratio that is inversely proportional to ${\theta}_x$ should be equivalent to ${\mu}_{max}$ in units, but exhibited the significant difference between theses two values. Therefore, it is considered that high safety factors are requested in the design of anoxic activated sludge process that is based on Monod bio-kinetics of microorganism.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.478-478
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• 2012

국내의 하수도 보급률은 90%에 달하고 있으며, 하수의 고도처리와 처리기술이 향상된 신기술개발 등으로 수질개선 효과가 크게 개선되어 있고, 전국 각지에 활발하게 하수처리장의 건설이 추진 중에 있지만, 다양한 오염원의 증가와 함께 환경기준은 점차적으로 강화되고 있어 기존 하수처리장은 강화되고 있는 환경기준을 만족시키기 어려운 실정으로 새로운 처리법의 도입이 절실히 요구되고 있는 실정이다. 시설이 노후화된 하수종말처리장의 경우에는 경제적인 부담감을 이유로 기존 공법 개선을 통한 수질기준을 만족하기 위하여 노력하고 있으며, 특히, 방류수 수질 중에서 총질소(T-N)와 총인(T-P)의 기준을 평상시와 겨울철(12월 1일부터 3월 31일까지)로 구분하여 적용하여 왔지만, 2012년부터는 이를 동일하게 적용함으로써 겨울철 생물학적 처리 공정에서의 효율저하로 인한 기준치 만족이 어려운 상황이다. 본 연구에서는 인천의 하수처리장을 대상으로 동절기 수온의 저하에 따른 생물학적 공정을 개선시키기 위하여 운전조건을 변경하여 수질개선 증대 방안을 도출하고자 하였으며, 생물학적 공정인 MLE공법으로 동절기 외부 온도의 영향을 받는 조건을 갖는 사업소를 대상으로 실내 실험장치를 구성하여 조건을 변화하면서 개선 효과를 검토하였다. 생물반응조의 공정위치 변화, 미생물농도 그리고 체류시간변화 등의 실험조건으로 하수 처리 효율을 분석하였으며, 운전 중 외부반송 유량, 내부반송 유량 등의 운전인자는 일정하게 유지하였고, 동절기 온도인 $10^{\circ}C$로 유지하여 실험을 진행하였다. 실험 결과 대상 하수처리장의 생물학적 공정의 개선방향은 공정 배열을 변화하였을 때, 현재의 공정 배열 조건인 무산소조 1개, 호기조 4개의 공정보다 호기조 1개, 무산소조 1개, 호기조 3개로 수정하는 경우 현재 공정보다 질소는 7%, 유기물은 9.2% 처리효율이 개선되는 것으로 분석되었다. 미생물 농도 변화를 주어 수질 개선 효과를 검토한 결과 하수처리장 설계농도인 3,500ppm의 경우보다 미생물 농도를 5,970ppm으로 증가시킨 경우 17.4% 처리효율의 개선효과를 보여 질소 제거를 위해 미생물의 농도를 증가시키는 것이 바람직한 것으로 판단하였다. 또한, 체류시간(HRT)을 변화한 경우에는 현재 체류시간(HRT)인 8시간 보다 10시간으로 증가시켰을 경우 유기물은 3.2%, 질소는 2.6%의 처리효율이 개선되는 것으로 분석되었다.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1093-1101
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• 2000

The object of this study was to develop new BNR process using fixed-biofilm which could be applied to retrofit the existing wastewater treatment plant or to introduce as tertiary treatment plant. To achieve complete denitrification from typical raw sewage in Korea, external carbon source must be supplied because $SCOD_{cr}/T-N(NH_4{^+}-N+NOx-N)$of raw sewage was lower than other countries. In this study, the ratio of $SCOD_{cr}/NH_4{^+}-N$ was 2.49 and the influent $NH_4{^+}$-N concentration during the experimental period was varied from 25 to 37 mg/L. To enhance nitrogen removal from the sewage, the two processes using fixed biofilm were adopted as R-Hanoxic/mid.settler/aerobic/anoxic/ aerobic) and R-2(aerobic/mid.settlerlanoxic/anoxic/aerobic), respectively. In the comparison of $NH_4{^+}$-N, T-N effluent quality and T-N removal efficiency in both processes without external carbon source, R-1 process was better than R-2 process for nitrogen removal from raw sewage. With respect to $SCOD_{cr}$/NOx-N ratio and total nitrogen removal in each anoxic reactor of two processes, R-1's was more effective than R-2's for distributing organic matters of raw sewage. In the both processes using fixed biofilm, the amount of required alkalinity to remove unit $NH_4{^+}$-N were 5.18 and 5.76($g{\cdot}CaCO_3/g{\cdot}NH_4{^+}-N_{removed}$), respectively and were lower than activated sludge BNR process(7.14).

• Journal of Soil and Groundwater Environment
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• v.9 no.1
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• pp.87-94
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• 2004

The effects of pretreatment of GAC and dissolved oxygen (DO) on the sorption capacity for ο-cresol were investigated using pretreated GAC under oxic and anoxic conditions. Virgin GAC was used with pretreated GACs by $O_2$, acid and base as sorbents. Sorption capacity of GAC was dependent on the oxygen conditions according to the pretreatment methods. Virgin GAC showed increased sorption capacity when DO was present in the solution, while $O_2$-pretreated GAC did not show any considerable capacity change. Acid- and base-pretreated GACs were relatively more influenced by presence of DO as compared with virgin GAC. Both acid and base-pretreated GACs showed a rapid sorption rate at the initial stage, but as contact time became longer the sorption was slower. Sorbed ο-cresol was extracted with micro-Soxhlet extraction apparatus using the GAC separated from the rate experiments. Within 1 hour both acid and base-pretreated GACs showed the decrease in extraction efficiencies under both oxic and anoxic conditions. After 1 hour such a trend (the increase as contact time was longer) was not observed and showed relatively constant efficiencies of 35∼50%. According to the results of this study $O_2$contacted with GAC before sorption as well as DO present in the solution during sorption could influence the GAC sorption capacity.

• Korean Journal of Environmental Agriculture
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• v.25 no.3
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• pp.202-210
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• 2006

To develop small-scale sewage treatment apparatus for detached house of agricultural village, a small-scale sewage treatment apparatus by natural purification method that consisted of packaged form of aerobic, anoxic and anaerobic bed was constructed. The efficiency of sewage treatment according to the sewage treatment method, sewage loading, and the injection method of sewage were investigated for small-scale sewage treatment apparatus of packaged form of aerobic, anoxic and anaerobic bed. The removal rate of pollutants according to the sewage treatment method for small-scale sewage treatment apparatus was high in the order of aerobic-anoxic-anoxic bed < aerobic-anoxic-anaerobic bed. The optimum filter media in small-scale sewage treatment apparatus was a broken stone. The removal rate of pollutants according to sewage loading in small-scale sewage treatment apparatus was high in the order of $1,200L/m^2{\cdot}day\fallingdotseq900L/m^2{\cdot}day\fallingdotseq600L/m^2{\cdot}day$. The removal rate of pollutants according to injection method of sewage in small-scale sewage treatment apparatus was high in the order of continuous injection $\fallingdotseq$ intermittent injection. When loaded under the optimum conditions, removal rate of BOD, COD, SS, T-N and T-P were 99, 95, 99, 83 and 96%, respectively, through this 3-stepped small-scale treatment apparatus arrayed with the order of aerobic, anoxic and anaerobic bed.

• Journal of Life Science
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• v.15 no.4 s.71
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• pp.590-594
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• 2005

In this study, the wastewater treatment was conducted to evaluate the removal efficiency of total nitrogen from synthetic wastewater in the F-STEP PROCESS $(anaerobic{\rightarrow}\;oxic\;{\rightarrow}\;anoxic)$ with loess ball as support metrics. The average removal efficiencies of total nitrogen and ammonia nitrogen were $83.0\%\;and\;84.4\%$, respectively. The average nitrification efficiency at the oxic area was $60.9\%$ in the pH range of effluent water between 4.8 and 6.0. On the other hand, in the case of pH range of effluent water between 6.5 and 7.5, the denitrification efficiency at the anoxic area was $96.3\%$. The average concentration of COD was 12.8 ppm and the removal efficiency of COD in the F-STEP PROCESS were $96.3\%$. In the case of SS, the average concentration was $7.0\%$ at the effluent.

• Journal of Animal Science and Technology
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• v.46 no.2
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• pp.251-260
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• 2004

The feasibility and stability of ORP, pH(mV) and DO as a real-time control parameter for SBR process were evaluated in this study. During operation, NBP(nitrogen break point) and NKP(nitrate knee point), which reveal the biological and chemical changes of pollutants, were clearly observed on ORP and pH(mV)-time profiles, and those control points were easily detected by tracking the moving slope changes(MSC). However, when balance of aeration rate to loading rate, or to OUR(oxygen uptake rate), was not optimally maintained, either false NBP was occurred on ORP and DO curves before the appearance of real NBP or specific NBP feature was disappeared on ORP curve. Under that condition, however, very distinct NBP was found on pH(mV)-time profile, and stable detection of that point was feasible by tracking MSC. These results might mean that pH(mV) is superior real-time control parameter for aerobic process than ORP and DO. Meanwhile, as a real-time control parameter for anoxic process, ORP was very stable and more useful parameter than others. Based on these results, a stable real-time control of process can be achieved by using the ORP and pH(mv) parameters in combination rather than using separately. A complete removal of pollutants could be always ensured with this real-time control technology, despite the variations of wastewater and operation condition, as well as an optimization of treatment time and capacity could be feasible.

• Economic and Environmental Geology
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• v.55 no.6
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• pp.727-736
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• 2022

Ice wedges are subsurface ice mass structures that formed mainly by freezing precipitation with airborne dust and surrounding soil particles flowed through the active layer into the cracks growing by repeating thermal contractions in the deeper permafrost layer over time. These ice masses characteristically contain high concentrations of solutes and solids. Because of their unique properties and distribution, the possibility of harnessing ice wedges as an alternative archive for reconstructing paleoclimate and paleoenvironment has been recently suggested despite limited studies. It is imperative to preserve the physicochemical properties of the ice wedge (e.g., solute concentration, mineral particles) without any potential alteration to use it as a proxy for reconstructing the paleo-information. Thawing the ice wedge samples is prerequisite for the assessment of their physicochemical properties, during which the paleo-information could be unintentionally altered by any methodological artifact. This study examined the effect of thawing conditions and procedures on the physicochemical properties of solutes and solid particles in ice wedge samples collected from Cyuie, East Siberia. Four different thawing conditions with varying temperatures (4 and 23℃) and oxygen exposures (oxic and anoxic) for the ice wedge sample treatment were examined. Ice wedge samples thawed at 4℃ under anoxic conditions, wherein biological activity and oxidation were kept to a minimum, were set as the standard thawing conditions to which the effects of temperature and oxygen were compared. The results indicate that temperature and oxygen exposure have negligible effects on the physicochemical characteristics of the solid particles. However, the chemical features of the solution (e.g., pH, electric conductivity, alkalinity, and concentration of major cations and trace elements) at 4℃ under oxic conditions were considerably altered, compared to those measured under the standard thawing conditions. This study shows that the thawing condition of ice wedge samples can affect their chemical features and thereby the geochemical information therein for the reconstruction of the paleoclimate and/or paleoenvironment.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.521-526
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• 2006

A membrane bioreactor (MBR) is an effective tool for wastewater treatment with recycling. MBR process has several advantages over conventional activated sludge process (ASP); reliability, compactness, and quality of treated water. The resulting high-quality and disinfected effluents suggest that MBR process can be suitable for the reused and recycling of wastewater. An anoxic/oxic (A/O) type MBR was applied to simultaneous removal of organics and nutrients in sewage. At first, the efficiency of submerged MBR process was investigated using a hollow fiber microfiltration membrane with a constant flux of $10.2L/m^2{\cdot}h$ at each solids retention time (SRT). Results showed that protein/carbohydrate (P/C) ratio increased and total extracellular polymeric substances (EPS) remained constant with SRT increased. Secondly, A/O type MBR with a reverse osmosis (RO) membrane was employed to treat the municipal wastewater. The performance of A/O type MBR-RO process is better for the treatment of organics and nutrients than ASP-MF-RO process in terms of consistent effluents quality.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.5
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• pp.519-524
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• 2005

Due to the low C/N ratio of domestic wastewater characteristic, addition of external carbon source for the effective N and P removal is necessary. High organic content of food waste can be used for the external carbon source in biological nutrient removal processes, The applicability of condensate of food waste (CFW), which is produced during the high-rate fermentation process, was examined in membrane bioreactor for the nutrient removal. Under the various operating conditions, nutrient removal efficiencies and membrane fouling characteristics were evaluated using synthetic wastewater. From nitrate utilization rate (NUR) test, denitrification rate was 0.19 g $NO_3-N/g$ VSS/day. With the addition of CFW increased, average removal efficiencies of T-N and T-P could be increased up to 64% and 41%, respectively. Also the optimal retention time was 3 hr/5 hr for anoxic/aerobic reactor. When applied to real sewage, membrane fouling resistance was increased up to 60%, which could be reduced from $10.4{\times}10^{12}m^{-1}$ to $5.9{\times}10^{12}m^{-1}$ with the control of influent suspended solid concentration. In summary, it was suggested that CFW could be used as an economical and effective carbon source for membrane assisted biological N and P removal.