• Journal of the Korean Society for Marine Environment & Energy
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• v.7 no.4
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• pp.159-163
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• 2004

This study was performed to estimate the water quality of pH, salinity, dissolved oxygen, ammonium and sulfur hydroxides of sediment in shrimp aquaculture farms of Southwestern coastal of Korea from June to September, 2003. We surveyed the status of water quality and achieved the improve water and sediment quality to restraint the production of ammonium and sulfur hydroxides from sediment of shrimp aquaculture farms. The concentrations of dissolved oxygen increased from noon to the evening for 6 hour and decreased to 2.98 ppm at six o'clock in the next morning and increased repeatedly, even though DO level has a different level in sunny day and cloudy day. This results suggest that the most importance time of the control of DO in shrimp aquaculture farm is next early morning and if the DO concentration increased continuously which may be growing up the concentrations of NH₄/sup +/ and H₂S. The measured of pH and salinity were suitable to growth of shrimp. However, the level of ammonium and sulfur hydroxides produced from the sediments of shrimp aquaculture farms were 2.30 ppm and 0.075 ppm, respectively, which are exceeded to the concentration of guide line for the growth of shrimp. In the results of this study, we found it difficult to improve the water quality using of the present frame of shrimp aquaculture farms. Then, we can improved water quality of DO, NH₄/sup +/ and sediment quality of ORP, H₂S and also achieved down to the rate of shrimp fatal by changed the frame of shrimp aquaculture farms in the scale of laboratory.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.189-192
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• 1998

This paper presents the basis for the need of feed-water deaerator installation in nuclear power plant and has been conducting reviews to understand the mechanism of dissolved oxygen(DO) formation as well as removal. DO is produced by feedwater make-up, air inleakage in vacuum system and condensation in condenser, etc. and removed by mechanical method and chemical method. DO has an influence on S/G in the form of denting, pitting, fretting, etc. DO control by deaerator has an great effect on the integrity of S/G in nuclear power plant.

• Environmental Engineering Research
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• v.25 no.2
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• pp.212-221
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• 2020

This work discusses the palm oil mill processing carried out at Jugra Palm Oil Mill Sdn Bhd, situated at Selangor, Malaysia with the capacity of 45-t fresh fruit bunch (FFB)/h. Typically, oil palm residues and palm oil mill effluent (POME) from FFB are generated while processing. Prior to discharge, POME should be treated to remove pollutants in the effluent. As such, the performances of anaerobic and aerobic ponds were assessed in this study to determine temperature, pH, biological oxygen demand (BOD), sludge volume index (SVI), and dissolved oxygen (DO). From the experiments, mesophilic temperature due to better process stability was applied in anaerobic ponds. The pH results displayed a fluctuating trend between lower control limit and upper control limit, and, the pH value increased from one pond to another. The final discharge BOD and SVI appeared to be lower than 100 mg/L and 10 mL/L indicating low degree of pollution and good settling ability for biomass/solid. DO was close to normal, mostly below 2 mg/L. The experimental outcomes revealed the effective treatability of POME in adherence to the standard regulation, which is the priority for environmental sustainability within this industry domain.

• Journal of Biosystems Engineering
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• v.20 no.4
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• pp.383-389
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• 1995

This study was conducted to develop an automatic nutrient control system for trickle application of nutrient solution. Temperature, electric conductivity(EC). pH and dissolved oxygen(DO) were selected as control variables. A controller using single-chip microcomputer was constructed. An automatic control system for nutrient solution and a controller using single-chip microcomputer with control algorithm were developed. The control system was tested, and could control temperature, EC and pH within the error ranges of $pm 0.2^{circ} pm 0.2mS/cm, pm 0.1pH$, respectively.

• Korean Journal of Food Science and Technology
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• v.34 no.3
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• pp.361-364
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• 2002

This study was performed to establish a simple and accurate method for the determination of oxygen that is a processing aid in various beverage. The quantitative determination of dissolved oxygen (DO) contents in 30 cases of samples were performed by traditional titration method and polarography. As a result of the study, the analysis of DO contents in fruit-extract beverages containing oxygen by titration method was time consuming and large sample volumes were needed. Besides, serious interferences with compounds such as hydroxylamine and nitric oxide were observed, leading to false response. Although the polarography is easily affected by $H_2S$, proteins, and various organic compounds, it is a simple and practical method that provides inexpensive and relatively rapid analysis. The polarography is best suited to the routine determination of DO in a large number of samples and it is expected that the polarography can directly be applied to the quality control of the beverages containing added oxygen. The analysis results of DO contents in various fruit-extract beverages with oxygen and without oxygen were as follows: 23.10 ppm to 32.60 ppm for various frutis extract beverages with oxygen, 0.70 pp to 2.54 ppm for mixed beverages without oxygen, 7.63 ppm to 8.28 ppm for drinking water.

• Korean Chemical Engineering Research
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• v.45 no.1
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• pp.73-80
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• 2007

This article aims to optimize the nitrogen removal of a sequencing batch reactor (SBR) through the use of the activated sludge model and iterative dynamic programming (IDP). Using a minimum batch time and a maximum nitrogen removal for minimum energy consumption, a performance index is developed on the basis of minimum area criteria for SBR optimization. Choosing area as the performance index makes the optimization problem simpler and a proper weighting in the performance index makes it possible to solve minimum time and energy problem of SBR simultaneously. The optimized results show that the optimal set-point of dissolved oxygen affects both the total batch time and total energy cost. For two different influent loadings, IDP-based SBR optimizations suggest each supervisory control of batch scheduling and set-point trajectory of dissolved oxygen (DO) concentration, and can save 20% of the total energy cost, while meeting the treatment requirements of COD and nitrogen. Moreover, it shows that the re-optimization of IDP within a batch can solve the modelling error problem due to the influent loading changes, or the process faults.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.3 no.2
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• pp.113-119
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• 1999

The quality of the effluent from an activated sludge aeration tank can deteriorate when the substrate removal rate decreases due to an abrupt reduction in the DO concentration, which is affected by such operating conditions as the loading rate, temperature, wastewater composition, and so on. In this research, a DO control system that includes a PI (proportional-integral) controller/Hiraoka controller was developed and applied to a pilot-scale activated sludge process, then its acceptability was estimated. The applicability of the respiration rate to DO control was also estimated. The respiration rate indicated a variety of input organic loading rates, which is the main disturbance to the DO concentration in an aeration tank. When the influent concentration incrementally decreased and increased between CODcr 1,000 mg/l and 100 mg/l, the control system with a PI controller exhibited a good llperformance-the average DO concentrations were 2.00$\pm$0.14 mg/l and 1.88$\pm$0.15 mg/l (set value was 2.0 mg/l), respectively, and the settling time was just 10 minites. When the control system was operated for 4 days, the DO concentration was 1.99$\pm$0.18 mg/l and 32.6% of the air flowrate was saved. However, the fluctuations in the respiration rates and air flowrates were severe, which could be harmful to the stability of the biomass and mechanical stability of the blower. A possible approach to solve this problem may be the simultaneous control of the loading rate and DO concentration.

• Journal of Ecology and Environment
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• v.41 no.9
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• pp.235-245
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• 2017

Background: Loading of excess nutrient via bioremediation of polluted sediment to overlying water could trigger anoxia and eutrophication in coastal area. The aim of this research was to understand the changes of overlying water features such as dissolved oxygen (DO); pH; oxidation reduction potential (ORP); $chlorophyll-{\alpha}$ ($Chl-{\alpha}$); and nitrogen nutrients ammonia ($N-NH_4{^+}$), nitrate ($N-NO_3{^-}$), and nitrite ($N-NO_2^-$) when the sediment was not treated (control) and treated by calcium peroxide for 5 weeks. Methods: The water samples were analyzed for measuring physical and chemical properties along with the sediment analyzed by polymerase chain reaction (PCR) including denaturing gradient gel electrophoresis (DGGE) for identifying the phylogenetic affiliation of microbial communities. Results: Results showed that due to the addition of calcium peroxide in sediment, the overlying water exposed the rise of dissolve oxygen, pH, and ORP than control. Among the nitrogen nutrients, ammonia inhibition was higher in calcium peroxide treatment than control but in case of nitrate inhibition, it was reversed than control. $Chlorophyll-{\alpha}$ was declined in treatment column water by 30% where it was 20% in control column water. Actibacter and Salegentibacter group were detectable in the calcium-peroxide-treated sediment; in contrary, no detectable community ware found in control sediment. Both phylogenetic groups are closely related to marine microflora. Conclusions: This study emphasizes the importance of calcium peroxide as an oxygen release material. Interaction with peroxide proved to be enhancing the formation of microbial community that are beneficial for biodegradation and spontaneity of nutrient attenuation into overlying water.

• Proceedings of the KAIS Fall Conference
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• 2010.11b
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• pp.1025-1028
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• 2010

The bacteriological examination of spring water in Seogwipo-city was conducted. A total 11 spring water samples were performed from January to April, 2010. During the study period, the range of temperature was from 0.7 to $15.4^{\circ}C$, and result of the analyses showed that hydrogen ion concentrations (pH) for spring water was 0.33 to 7.8. salinity levels for sample average of 0.5 to 1.04‰, as the result of measuring dissolved oxygen (DO) for spring water showed that water dissolved oxygen were 1.02 to 7.14 mg/${\ell}$. The range of total coliform of spring water sample at 11 stations located in the designated spring water were <1.8~>1,600 MPN/100mL. And the range of geometric mean of total coliform were 1.9~117.1 MPN/100mL, The range of fecal coliform of spring water sample at 11 stations located in the designated spring water were <1.8~>1,600 MPN/100mL. And the range of geometric mean of fecal coliform were 1.8~68.1 MPN/100mL, respectively. Level of microbial contamination was examined in 11 samples for indication of bacterial contamination such as heterophic bacteria, EscherichiacoliO157;H7, salmonella spp., Vibrio parahaemolyticus, Staphylococcus aureus, Shigella spp. Were frequently detected from the spring water. Salmonella spp., S.aureus were detected in the range of $0{\sim}1.0{\times}10^1$, $0{\sim}3.0{\times}10^1$ CFU/ml, respectively. And the Escherichia coli O157;H7, Vibrio parahaemolyticus, Shigella spp. Were not detected from the examined spring water samples.

• Journal of Microbiology and Biotechnology
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• v.19 no.6
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• pp.596-603
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• 2009

This study aimed to examine the influence of adding an oxygen vector, n-dodecane, on hyaluronic acid (HA) production by batch culture of Streptococcus zooepidemicus. Owing to the high viscosity of culture broth, microbial HA production during 8-16 h was limited by the oxygen transfer coefficient $K_La$, which could be enhanced by adding n-dodecane. With the addition of n-dodecane to the culture medium to a final concentration of 5% (v/v), the average value of $K_La$ during 8-16 h was increased to $36{\pm}2h^{-1}$, which was 3.6 times that of the control without n-dodecane addition. With the increased $K_La$ and dissolved oxygen (DO) by adding 5% (v/v) of n-dodecane, a 30% increase of HA production was observed compared with the control. Furthermore, the comparison of the oxygen mass transfer in the absence and presence of n-dodecane was conducted with two proposed mathematical models. The use of n-dodecane as an oxygen vector, as described in this paper, provides an efficient alternative for the optimization of other aerobic biopolymer productions, where $K_La$ is usually a limiting factor.