• Ocean and Polar Research
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• v.45 no.3
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• pp.103-111
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• 2023

To evaluate the impact of effluents from land-based fish farms on the coastal ocean of Wando, Korea, we analyzed inorganic nutrients, particulate organic carbon (POC), dissolved organic carbon (DOC), and colored dissolved organic matter (CDOM) in the effluent and influent of land-based fish farms during the summer (July) of 2021. The average concentrations of nutrients (Dissolved inorganic nitrogen, phosphorus, and silicate; DIN, DIP, and DSi, respectively) in the effluents of this study area were 17±3.7 μM, 1.4±0.7 μM, and 14±1.6 μM, respectively. The average concentrations of POC and DOC were 37±22 μM and 81±13 μM, respectively, with POC accounting for about 30% for total organic carbon in effluents. The Reduced Dissolved Inorganic Nitrogen/Total Dissolved Inorganic Nitrogen ratio (0.7), potential short-period index, indicates that the discharge of nutrients excreted by the fish and unconsumed feed into coastal water results in such nutrients being deposited and accumulated in the sediment. Subsequently, this continuous accumulation triggers the release of ammonium ions during organic matter decomposition, and the ammonium-enriched waters that encroach on fish farms as influent seem to be due to the diffusion of high concentrations of ammonium from bottom sediment. Furthermore, we used fluorescence indices to examine the characteristics of organic matter sources, obtaining mean values of 1.54±0.19, 1.06±0.06, and 1.56±0.06 for the humification index, biological index, and fluorescence index, respectively, in the effluent. These results indicate that the organic matters had an autochthonous origin that resulted from microbial decomposition, and such organic matters were rapidly generated and removed by biological activity, likely supplied from the sediment. Our results suggest that the effluent from land-based fish farms could be a potential source of deoxygenation occurrence in coastal areas.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.25 no.4
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• pp.81-96
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• 2020

Berthlot's reaction spectrophotometric method is generally used for the analysis of dissolved ammonium in seawater, but in recent years, a fluorescence method using an orthophthaldialdehyde-sulfite (OPA) fluorescent reagent is actively used internationally. In this study, we investigated the effects of the detection limit between the analysis methods, the reagent refractive index inherent in the spectrophotometric method, and the use of different calibration curves to understand the cause of the difference in dissolved ammonium concentration (about 0.31 𝜇M) observed in the seawater samples and a nutrient reference material between two institutions (KIOST (spectrophotometric method, one-order linear regression gradient only), Australia CSIRO (fluorescence method, quadratic formula)) conducted onboard the Australian R/V Investigator in 2017. The method detection limit (0.063 𝜇M) and the reagent refractive index background value (0.054 𝜇M) of the spectrophotometric method measured in this study could explain the difference in dissolved ammonium concentration values of the two institutes about 20% and 17%, respectively. However, when the concentration of the calibration curve of the spectrophotometric method was calculated using the same quadratic as the fluorescence method or the slope and intercept of linear regression, the difference in the dissolved ammonium concentration between the two institutions was reduced to less than the detection limit of the spectrophotometric method. Therefore, the difference in the concentration of dissolved ammonium between the two institutions, found in the nutrient reference materials and the seawater field sample during the international onboard nutrient inter-comparison experiment, may be attributed to be the effect of the different calibration curves used in the two methods rather than the effect of the difference in two analytical methods. When comparing the dissolved ammonium data from seawater samples in the future, it is recommended to pay attention to the information on the baseline, number of standard solutions, and calibration curve used in the analysis.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.457-460
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• 2000

A biofilm airlift reactor filled with biomass-covered carriers (sand) were used to remove ammonium by selective nitrification (ammonium to nitrite). The effects of experimental conditions (ammonium load, pH, dissolved oxygen) on nitrification and nitrite accumulation were investigated. The reactor showed more than 90% nitrification efficiencies at 2.5 kg $NH_4\;^+-N/m^3/d$ and $NO_2\;^--N$ could be accumulated between 75% and 90% in the effluent. It is likely that nitratation (nitrite oxidizer) was inhibited by low dissolved oxygen concentration while nitritation (ammonium oxidizer) was kept stable.

• KSBB Journal
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• v.16 no.6
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• pp.573-578
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• 2001

The effects of organic supplement (acetate) and dissolved oxygen concentration on the nitrification rate of wastewater were investigated in the 27.7 L pilot-scale airlift biofilm reactor with the granular activated carbon media of 0.613 mm diameter. The ammonium oxidation rate increased stepwise up to 5 kg N/㎥$.$d at the riser air velocity of 0.063 m/s, when the air velocity and the ammonium loading rate were raised alternately. The nitrite build-up was observed during the early stage of the biofilm formation, which disappeared after the reactor operation of 128 days. As increasing the organic loading rate, the organic oxidation rate increased up to 25.0 kg COD/㎥$.$d with the removal efficiency of 94% but the oxidation rates of ammonium and nitrite decreased. The oxidation rates of ammonium and nitrite increased with the dissolved oxygen concentrations. When the pure oxygen was sparged, the ammonium oxidation rate was almost five times higher than that with air at the same velocity.

• Textile Coloration and Finishing
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• v.33 no.2
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• pp.72-78
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• 2021

The purpose of this study, the purpose of this study is to activate the antibacterial effect on the Chlorinated polyvinyl chloride film by using Octadecyldimethyl (3-triethoxy silylpropyl) ammonium chloride antibacterial agent with Chlorinated polyvinyl chloride polymer, which is inexpensive and has excellent properties such as heat resistance and chemical resistance. The Chlorinated polyvinyl chloride polymer was dissolved in a dimethylacetamide solvent, and film samples were prepared by varying the ratio of Octadecyldimethyl (3-triethoxy silylpropyl) ammonium chloride to study the antibacterial performance. A Scanning Electron Microscope-Energy Dispersive X-ray Spectrometer and X-ray photoelectron spectroscopy were employed to confirm the elements in the samples. According to the initial decomposition temperature of the Chlorinated polyvinyl chloride film and the Chlorinated polyvinyl chloride/Octadecyldimet hyl (3-triethoxy silylpropyl) ammonium chloride(10%) film using a Thermogravimetric analyzer(TA-DTA), it was confirmed that the initial decomposition temperature was lowered due to the influence of Octadecyldimethyl (3-triethoxy silylpropyl) ammonium chloride. In addition, in order to measure the mechanical properties, Universal testing machine was used and the result showed that a strength of Chlorinated polyvinyl chloride/Octadecyldimethyl (3-triethoxy silylpropyl) ammonium chloride(10%) was 36.8 MPa. The antimicrobial properties of the Chlorinated polyvinyl chloride/Octadecyldimethyl (3-triethoxy silylpropyl) ammonium chloride(10%) film showed 99.9% antimicrobial properties.

• Textile Coloration and Finishing
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• v.31 no.4
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• pp.276-287
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• 2019

In this study, cotton fibers were coated with a different weight percentage of octadecyl dimethyl(3-triethoxy silylpropyl) ammonium chloride(ODDMAC) to improve antimicrobial and water repellent properties. First, the ODDMAC dissolved in ethanol to prepare a solution. Then the cotton fibers were immersed in the ODDMAC/ethanol solution for 10 minutes at ambient temperature and dried at 80℃ for 3 minutes followed by curing. The treated cotton fibers were characterized by scanning electron microscopy(SEM) and x-ray photoelectron spectroscopy(XPS). The treated cotton fibers revealed sufficient antimicrobial activity against Klebsiella pneumoniae(ATCC 4352) and Staphylococcus aureus(ATCCBAA-1707). The hydrophobic nature of the treated cotton fibers was characterized by contact angle measurement. The results showed that the cotton fibers treated with the ODDMAC showed excellent hydrophobic properties which improved to 121°.

• Journal of Ecology and Environment
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• v.30 no.3
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• pp.209-223
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• 2007

Twenty-four wetlands located in Higashi-Hiroshima City in West Japan were selected for this study in order to investigate both the relationship between aquatic plant composition and environmental conditions; and the relationship between changing land use patterns in the catchments and the concentration of different forms of nitrogen in the wetlands. The dominant and subdominant species which comprised the principal vegetation were determined based on a vegetation census conducted in each wetland during the growing season from June to August, 2006. The seasonal variations of water quality factors (pH, electrical conductivity, turbidity, dissolved oxygen, total dissolved solid, and temperature) and different forms of nitrogen such as nitrite, nitrate, ammonium, total nitrogen, dissolved organic nitrogen and dissolved inorganic nitrogen concentrations were analyzed as important indicators of water quality for the surface water of the wetlands. The surveyed wetlands were classified into three types (non-disturbed wetlands, moderately-disturbed wetlands and highly-disturbed wetlands), based on the degree of human disturbance to their catchment areas. An analysis of variance indicated that there was a significant difference among the wetland groups in the annual mean values of electrical conductivity, total dissolved solids, total nitrogen, nitrite, dissolved inorganic nitrogen and dissolved organic nitrogen. Classification of the wetlands into three groups has revealed a pattern of changes in the composition of plant species in the wetlands and a pattern of changes in nitrogen concentrations. A majority of the non-disturbed wetlands were characterized by Brasenia schrebi and Trapa bispinosa as dominant; with Potamogeton fryeri and Iris pesudacorus as sub-dominant species. For most of the moderately-disturbed wetlands, Brasenia schrebi were shown to be a dominant species; Elocheriss kuriguwai and Phragmites australis were observed as sub-dominant species. For a majority of the highly-disturbed wetlands, Typha latifolia and T. angustifolia were observed as dominant species, and Nymphea tetragona as the sub-dominant species in the study area. An analysis of land use and water quality factors indicated that forest area played a considerable role in reducing the concentration of nutrients, and can act as a sink for surface/subsurface nutrient inputs flowing into wetland water, anchor the soil, and lower erosion rates into wetlands.

• Korean Journal of Environmental Agriculture
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• v.17 no.1
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• pp.43-47
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• 1998

This study was performed to remove the dissolved benzene in water by using TMA-Zeolite complex which was formed by the adsorption of TMA(Tetramethyl ammonium), a kind of ration surfactant on a natural zeolite produced in Korea. The dorminant clay minerals of the natural zeolite was identified by X-ray diffractometry and Infrared spectrophotometry to be mordenite and clinoptilolite. The CEC of the zeolite used was 95.9 cmol/kg. TMA was adsorbed on natural zeolite very quickly, and the amount of TMA adsorption on zeolite was known to be equivalent to about 8% of the CEC of natrual zeolite. The amount of benzene adsorption on TMA-zeolite complex was much more than natural zeolite, indicating that the dissolved benzene in water could be removed effectively by TMA-zeolite comple.

• 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.

• Journal of Microbiology and Biotechnology
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• v.16 no.3
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• pp.469-474
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• 2006

Partial nitrification blocking of the oxidation of nitrite ($NO_{2}^{-}$) to nitrate ($NO_{3}^{-}$) has cost-efficient advantages such as lower oxygen and organics demand for nitrification and denitrification, respectively. A nitrifying membrane bioreactor of submerged type was operated for the treatment of synthetic ammonium wastewater with the purpose of nitrite build-up without affecting the efficiency of ammonium oxidation. A high ammonium concentration (1,000 mg/l) was completely converted to nitrate at up to 2 kg $N/m^3$ day under sufficient aeration. The control of pH under sufficient aeration was not a reliable strategy to maintain stable nitrite build-up. When the dissolved oxygen concentration was kept at 0.2-0.4 mg/l by adjusting the aeration rate, about 70% of nitrite content was obtained with ammonium oxidation efficiency higher than 93%. The increase of suction pressure due to membrane fouling was not significant under lowered aerating environment over a 6-month period of operation. The composition of nitrifier community, including relative abundance of nitrite oxidizers in a nitrite-accumulating condition, was quantified by fluorescence in situ hybridization analysis.