• 한국환경보건학회지
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• 제20권2호
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• pp.28-38
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• 1994

New problems have been recently posed on the abnormal foaming (Scum) in an aeration tank and the sludge flotation in a final sedimentation tank during the activated sludge process. However, the activities of the causing bacteria, Nocardia-amarae in an aeration tank have not been searched out at all. Therefore, in this article the activities of Nocardia-amarae in an aeration tank have been closely examined by means of the changes of (F/M) ratio, SRT and inflowing substrate using continuous type and fed-batch type. Summarized results of experiments are as follows. 1. Regrading continuous culture when synthetic wastewater was used substrate neither the increase in the number of Nocardia-amarae in the aeration tank nor the Occurrence of Scum was observed. 2. In the case of fed-batch culture, Nocardia-amarae in the aeration tank increased due to the partial change in substrate and the effect of SRT was significant. 3. Once the scum was formed and the quantity of added Nocardia-amarae and substrate were not changed, the effect of STR was not significant.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.685-691
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• 1996

Recent research in composting greenhouse has focused on some of the fundamental properties during the process such as temperature , carbon dioxide content and odors which change as the composting progresses. The composting greenhouse of cattle manure with rice hulls by a forced aeration method without turning is available for the practical proposition. The control of a predetermined temperature range(45-65$^{\circ}C$) is possible if intermittent aeration is used. The carbon dioxide concentration was maintained in the range from 400 to 2650 ppm by the intermittent aeration. The ammonia emission rose rapidly leading to a temperature increase of composting material up to more than 60$^{\circ}C$ for six days. Ammonia emission declined quickly and could hardly be detected after 10 days of running period.

• 한국물환경학회지
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• 제36권6호
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• pp.535-545
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• 2020

This study aims to conserve and monitor energy use in public sewage treatment plants by utilizing data from the SCADA system and by controlling the aeration rate required for maintaining effluent water quality. Power consumption in the sewage treatment process was predicted using the equipment's uptime, efficiency, and inherent power consumption. The predicted energy consumption was calibrated by measured data. Additionally, energy efficiency indicators were proposed based on statistical data for energy use, capacity, and effluent quality. In one case study, a sewage treatment plant operated via the SBR process used ~30% of energy consumed in maintaining the bioreactors and treated water tanks (included decanting pump and cleaning systems). Energy consumption analysis with the K-ECO Tool-kit was conducted for unit processing. The results showed that about 58.7% of total energy consumed was used in the preliminary and biological treatment rotating equipment such as the blower and pump. In addition, the energy consumption rate was higher to the order of 19.2% in the phosphorus removal process, 16.0% during sludge treatment, and 6.1% during disinfection and discharge. In terms of equipment energy usage, feeding and decanting pumps accounted for 40% of total energy consumed following 27% for blowers. By controlling the aeration rate based on the proposed feedback control system, the DO concentration was reduced by 56% compared pre-controls and the aeration amount decreased by 28%. The overall power consumption of the plant was reduced by 6% via aeration control.

• 한국환경과학회지
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• 제27권6호
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• pp.447-456
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• 2018

In this research, the target process was a modified type of a conventional aeration tank with four different influent feeding points and alternated aeration to obtain nitrogen removal. For more accurate switching of influent feeding, the process was operated under a designed control strategy based on monitoring of $NH_4-N$ and $NO_X-N$ concentrations in the tank. However, the strategy did have some limitations. For example, it was not sensitive to detecting the end of each reaction when losing the balance between nitrification and denitrification of each opposite part of biological tank. To overcome the limitations of the existing control strategy, a diagnosis-based control strategy was suggested in this research using the diagnosis results classified as normal (N), ammonia accumulation (AA) and nitrate accumulation (NA). Using the pre-designed rules for control actions, the aeration and volume of the aerated part of the reactor could be increased or decreased at a fixed mode time. In simulations of the suggested diagnosis-based control strategy, the $NH_4-N$ and $NO_X-N$ removal rates in the reactor were maintained at higher levels than those of the existing control strategy.

• 한국환경과학회지
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• 제8권4호
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• pp.533-538
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• 1999

Fuzzy algorithm of automatic control for dissolved oxygen(DO) concentration in the aeration tank of an activated sludge process is proposed. Among variables repirometry and air flowrate are selected as significant input factors and the relationship with DO is estimated using a multiple regression model. The DO concentration and the amount of repirometry are fuzzified and the fuzzy rule base are determined. Using the fuzzy algorithm, the change of amount of air flowrate are determined and the change of amount of DO is derived.

• 한국물환경학회지
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• 제18권3호
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• pp.261-270
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• 2002

The artificial aeration in the middle and the small scale reservoirs is widely used to destroy the stratified layer and algal boom. This study has been conducted at the Youncho reservoir located in Keoje island since Jan. 2000 to suggest the most suitable control strategy of the artificial aeration and reduce the side effect. The main results obtained from this research are as follows. The starting time of aeration for destratification was adjusted from the end of March to the beginning of April when the natural stratification is started. In order to prevent an anoxic condition the artificial mixing should be started by the middle of April when the DO in hypolimnion is dropped to less than $5mg/{\ell}$. The decrease DO, caused by the increase in water temperature, spreads rapidly from hypolimnion to themocline. Thermal stratification disappeared after the onset of artificial aeration within 7 days in the Yuncho reservoir. The air diffusers decrease water temperature in the layer of epilimnion and thermocline, but rise it in hypolimnion. The continuous operation of air diffuser prevent the stratification and anoxic condition in hypolimnion despite of the rising of water temperature and algal abundance. The algal abundance is not observed in effective zone by aeration. The turbidity rising problem induced from the aeration is avoided by keeping an air diffuser about 1.5m high from the bottom of lake. During the summer season, ceasing the aeration should be decided carefully. And also, it is necessary to operate the system it considering weather and temperature, and depending on the number and the position of aerators.

• Fisheries and Aquatic Sciences
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• 제11권4호
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• pp.224-228
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• 2008

With the aim of increasing the $CoQ_{10}$ production in mass culture, the effect of aeration-agitation on the $CoQ_{10}$ production using Rhodobactor sphaeroides was investigated in a l-L bioreactor. The maximum $CoQ_{10}$ production was 1.69 mg/g of dry cell weight under conditions of 50 Lux, $30^{\circ}C$, 300 rpm, and 5-vvm aeration. The $CoQ_{10}$ production was improved to produce 2.91 mg/g of dry cell weight under reduced conditions of agitation speed (200 rpm) and aeration rate (0.2 vvm). When R. sphaeroides was cultivated under more reduced DO levels during the exponential phase of the cell, the $CoQ_{10}$ production yield of 3.88-mg/g dry cell weight was the maximum obtained. Therefore, poorer conditions of aeration-agitation resulted in higher production of $CoQ_{10}$, and thus DO content was a crucial factor in the production of $CoQ_{10}$. Accordingly, it was necessary to control the DO concentration in order to enhance the $CoQ_{10}$ biosynthesis within a large-scale production.

• 한국물환경학회지
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• 제18권4호
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• pp.401-409
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• 2002

In this study, to evaluate the applicability of ORP and pH as process control parameters for an intermittent aeration process, a 200L/d bench-scale plant was installed and operated for 90 days. It was fed with synthetic wastewater which contained $COD_{Cr}$ : 400mg/L, TN : 40mg/L and TP : 7mg/L. ORP & pH were measured on-line and compared with the variation of nutrient concentrations. As the results, both of the ORP and pH were able to monitor successfully nitrification and denitrification. Bending-points on the ORP curve and peak points on the pH curve corresponded to the termination of nitrification and denitrification. For P uptake and release, pH was the best indicator for performance evaluation. The aerobic pH apex was appeared when P uptake was accomplished and there was a relationship between the P release and pH variation. But the pH curve needed filtering because there were many noises on it. In this study, the shape of the ORP & pH curves were varied as the operating conditions such as aeration rates and organic loads were changed. It allowed the operating states of biological systems to be effectively evaluated. If it is properly managed to show the bending points and peak points clearly, the on-line monitoring of ORP & pH will be a reliable and effective technique for process control of intermittent aeration processes.

• 유기물자원화
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• 제2권1호
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• pp.3-18
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• 1994

우리나라 도시고형폐기물은 퇴비화에 적합한 조건을 갖추고 있으나, 퇴비화 공정개발이 미약하여 폐기물 퇴비화를 실용화하지 못하고 있다. 폐기물 퇴비화의 실용화를 위하여는 최종퇴비의 질을 높이면서도 대량의 폐기물을 단기간에 처리할 수 있도록 공정제어를 하여야 한다. 이를 위하여 최적온도를 지속적으로 유지하도록 공기공급량을 제어하는 방식(온도제어 공기공급방식)이 있다. 본 연구에서는 우리나라 도시고형폐기물에 온도제어 공기공급방식을 적용하여 퇴비화 과정중의 공정효율과 최적온도를 분석하고자 하였다. 실험결과, 온도제어 공기공급방식이 일정공기공급방식에 비하여 짧은 기간에 분해효율과 건조효과가 높은 것으로 나타났다. 또한 우리나라 도시고형폐기물 퇴비화의 최적온도는 $50{\sim}54^{\circ}C$로 평가되었다.

• 상하수도학회지
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• 제16권6호
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• pp.717-725
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• 2002

A bench-scale submerged-type membrane filtration system (SMFS) was constructed to study a feasibility of membrane filtration for solid-liquid separation in water and wastewater treatment processes. In the case of applying the SMFS to a biological wastewater treatment process, so-called membrane bioreactor, aeration underneath membrane modules is usually employed in order to provide oxygen demand for microbial growth as well as to control membrane fouling. A study was investigated the effects of operation parameters by aeration intensity, feed concentration, foulant type and airlift pore size on critical flux. Critical flux tends to increase with aeration rate. Optimal aeration flow rate was found to be 10 L/min/module. Feed concentration and foulant type has a significant effect on membrane fouling and filtration performance. But downward position and pore size of airlift has no a significant effects on membrane fouling and filtration performance.