• Korean Chemical Engineering Research
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• v.55 no.1
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• pp.74-79
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• 2017

In this study, the optimization of several factors for Chlorella saccharophila cultivation was investigated. The studied factors were medium type, culture type, inoculum size, sugar/nitrogen source type and concentrations. As a result, the optimized conditions for C. saccharophila cultivation were found to be the best at 3% (v/v) inoculum, 30 g/L glucose and 0.95 g/L $NaNO_3$ under mixotrophic culture. Under the optimized condition, the content of oil was high at 12 day, whereas, the amount of biomass and chlorophyll were high at 10 day.

• KSBB Journal
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• v.10 no.4
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• pp.401-405
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• 1995

An open pond type photobioreactor for mass cultivation of S. platensis was designed and the growth parameters from different cultivation processes were compared. 0.30(1/day) of specific growth rate and 1.69(g/$\ell$) of maximum cell density were obtained from batch cultivation. In fed-batch cultivation, specific growth rate and maximum cell density were estimated as 0.22(1/day) and 1.75(g/$\ell$), respectively. Maximum biomass productively from continuous cultivation was obtained as 0.44 (g/$\ell$/day). It proves that an outdoors-mass cultivation of S. platensis considering optimal environmental condition is economically feasible. In addition, the biomass productivity was studied in two different mixing systems such as agitation and air sparging methods. The biomass productivity by an agitation method was better than that in an air sparging method.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.1
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• pp.52-62
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• 2014

As a case study of the changed aquatic environment due to an estuary dam, the Geum River Estuary Dam System (GREDS) has been investigated for the last two decades. We sought the similarities and differences in the disrupted aquatic environment between the estuarine and lacustrine sides of the GREDS. Both sides of the GREDS shared similar aquatic disruptions, such as elongated hydraulic residence times, deteriorated water quality, highly accumulated organic-rich sediments, and considerable siltation of river-transported materials prior to reaching coastal waters. The disruptions of water quality such as high nutrients concentration and frequent bloom of blue-green algal are much more noticeable in the reservoir than in the estuary. However serious siltation problem has been reported from the estuary, which will possibly threaten the proper functioning of the natural Kunsan Estuarine System.

• Journal of Wetlands Research
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• v.17 no.2
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• pp.155-162
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• 2015

This study was conducted to assess the removal characteristics of taste and odor causing compounds(2-MIB and geosmin) and micro organic matters. GAC and BAC process consisting of Ozone/AOP and activated carbon was applied. As a result, the influent concentration of 2-MIB 159 ng/L and geosmin 371 ng/L were removed 42% and 86% by ozone 1.0 mg/L, and 58%, 90% by AOP(ozone 1.0 mg/L + $H_2O_2$ 0.5 mg/L). Also it showed less than 2 ng/L effluent in GAC process and 99.8% removal efficiency in BAC process. Therefore, BAC process combining ozone/AOP and GAC is effective for persistent removal of micro organic matters, taste and odor. It is needed for optimization of Ozone/AOP process according to influent concentrations.

• Journal of Marine Life Science
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• v.1 no.2
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• pp.121-125
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• 2016

This study examined the feeding response of the harpacticoid copepod, Tigriopus japonicus exposed to WAF or CEWAF to understand whether decreased feeding of the copepod by oil exposure is induced by food avoidance or medium toxicity. In the medium without WAF, there was no difference in the ingestion rate of the copepod among all polluted diets those were exposed to different concentrations of WAF. The present of WAF in the medium however caused a decrease in the ingestion rate at 100% WAF treatment. In the mixed diet treatment with adhesive diatoms and Tetraselmis suecica, T. japonicus had significantly lower ingestion rate on adhesive diatoms than on others in the medium with CEWAF. As a result, decreased ingestion of T. japonicus by oil exposure was caused by oil toxicity in medium, which may not have directly related with an avoidance of polluted food organisms.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.203-214
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• 2018

Ballast water treated by sodium dichloroisocyanurate (NaDCC) injection method in ballast water management system (BWMS) contains reactive bromine, chlorine species and disinfection by-products (DBPs). In this study, we conducted whole effluent toxicity (WET) testing and ecological risk assessment (ERA) to investigate its ecotoxicological effects on the marine environment. WET testing was carried out for eight marine and fresh water organisms, i.e. diatom, Skeletonema costatum, Navicula pelliculosa, green algae, Dunaliella tertiolecta, Pseudokirchneriella subcapitata, rotifer, Brachionus plicatilis, Brachionus calyciflorus and fish, Cyprinodon variegatus, Pimephales promelas. The WET test revealed that diatom and green algae were the only organisms that showed apparent toxicity to the effluent; it showed no observed effect concentration (NOEC), lowest observable effect concentration (LOEC) and effect concentration of 50 % (EC50) values of 25.0 %, 50.0 % and over 100.0 %, respectively, in seawater conditions. In contrast, rotifer and fish showed no toxicities to the effluent in the all salinity conditions. Meanwhile, chemical analysis revealed that the BWMS effluent contained total of 25 DBPs such as bromate, isocyanuric acid, formaldehyde, chloropicrin, trihalomethanes (THMs), halogenated acetonitriles (HANs) and halogenated acetic acids (HAAs). Based on ERA, the 25 DBPs were not considered to have persistency, bioaccumulation and toxicity (PBT) properties. The ratio of predicted environmental concentration (PEC) to predicted no effect concentration (PNEC) of the all DBPs did not exceed 1.0 for general harbour environments, but isocyanuric acid, tribromomethane, chloropicrin and monochloroacetic acid exceed 1.0 for near ship environments. However, when NOEC (25.0%) of the WET test results where actual effluent was applied, it was concluded that the NaDCC injection method did not have unacceptable ecological risks to the general harbor including near ship environments.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.1
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• pp.55-61
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• 2003

This study was conducted to evaluate distribution and behavior characteristics of heavy metals for tidal flat sediments in the Saemankeum area. The value of heavy metal contents in the tidal flat sediments were higher than that surveyed in 1994, but showing that it's lower when compared with the value of Shiwha lake. Enrichment factors in the tidal flat sediments showed below 1 except for Pb and Zn. Metal excesses was appeared that Cu, Cr, Fe, Mn lacked and Pb, Zn were high. The correlation analysis between heavy metals and organic matters was found high positive relationship (r=0.424$\~$0.839), especially correlation coefficient between ignition loss and oxide Al, Fe, Mn showed high positive relationship above 0.7. The correlation analysis between Brain size and hear metals was found that as grain size was small, heavy metals contents were increased. Correlation coefficient between silt and heavy metals except for Cu, Pb showed high positive relationship as 0.552$\~$0.732.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.587-597
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• 2023

We evaluated the eutrophication of Saemangeum Lake, which causes abnormal growth of algae, using the Carlson index. Eutrophication characteristics of Saemangeum Lake were analyzed. For the study, water quality surveys were conducted at 7 stations in Saemangeum Lake every month in 2021. The concentration of Chl.a was slightly higher in the Mankyeong water system in winter, and slightly higher in the Dongjin water system in spring and summer, but overall, except for some periods, the concentration was similar to or lower than the lake water quality environmental standard of class 3. COD showed water quality similar to or above the lake quality environmental standard of grade 4 in both the Mankyeong and Dongjin water systems in the summer and Autumn. TOC concentrations were within lake water quality standard 3 at all sites. Total phosphorus concentrations exceeded the lake water quality standard of Class 4 and were higher in January and August after rainfall. In the correlation analysis between water quality factors, the correlation of organic matter, total phosphorus, and total nitrogen to salinity was relatively high. This reflected the water quality characteristics of freshwater, brackish water, and seawater areas due to seawater inflow through the drainage gate and freshwater inflow through upstream rivers. According to the characteristics of eutrophication fluctuations in Saemangeum Lake by trophic state index, the indices of Chl.a, SD, and TN showed water quality in the early stage of eutrophication, while the TP index showed a severe eutrophication state. The magnitude of the eutrophication index among water quality components was TSI(TP) > TSI(TN) > TSI(SD) > TSI(CHL) in all water systems. Quadrant analysis of the deviation of TSI(CHL) from TSI(TP) and TSI(SD) on a two-dimensional plane showed that there was no limiting effect of total phosphorus on algal growth in all water systems. In addition, the factors af ecting light attenuation appeared to be dominated by small particulate matter from outside sources.

• Korean Journal of Environmental Agriculture
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• v.20 no.4
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• pp.244-251
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• 2001

This study was performed to investigate the recovery efficacy of 2-methylisobomeol (2-MIB) and Geosmin, odor contaminants produced by algae, by pretreatment techniques, and also to investigate both adsorption characteristics and removal efficiency to get some information for the effective removal of 2-MIB and Geosmin by batch experiments. In pretreatment experiments, the best recovery efficiency of both odorants at 0.2 and $2\;{\mu}g/L$ in raw water was 30 mL of sampling size, 9 g NaCl for salting out headspace of sampling phase and 40 minutes of adsorption. At the best condition, the recovery efficiency of 2-MIB was 85% at $0.2\;{\mu}g/L$ and 95% at $2\;{\mu}g/L$, whereas the efficiency of Geosmin was lower than that of 2-MIB : 61% at $0.2\;{\mu}g/L$ and 81% at $2\;{\mu}g/L$. In batch experiments, the removal efficiency of the Geosmin and 2-MIB by adsorbents using distilled water were increased in comparison with raw water, the efficiency in raw water was little different by their concentrations. When these results were applied to the Freundrich adsorption isotherm, the K value of 2-MIB for zeolite, coal activated carbon, and coconut activated carbon was 0.671, 1.811, and 1.340, respectively, and the value of Geosmin was 0.6125, 1.771, and 1.5191, respectively. Thus the adsorption efficiency of 2-MIB and Geosmin was in the order of zeolite, coconut activated carbon, coal activated carbon.

• Korean Journal of Environmental Biology
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• v.23 no.2 s.58
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• pp.146-151
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• 2005

Recent studies indicated the utility of whole effluent assessment as a measure to control discharge of toxic effluents to receiving water in Korea. However, most studies have been focussed on acute lethal effects of toxic wastewater with little consideration of chronic sublethal impacts which are of growing concern in protecting aquatic ecosystem. We conducted acute and chronic toxicity tests with effluents discharged from five different dyeing plants in Gyeong-gi province using a marine bacterium Vibrio fischeri and a freshwater macroinvertebrate Daphnia magna to demonstrate the importance of assessing chronic sublethal effects. Various levels of acute and chronic toxicities were observed in many samples tested in this study. In 21-d chronic toxicity tests using D. magna all samples showed effects on reproduction and growth. Notable mortalities were also noted in three out of five effluents. The result of the Microtox assay indicated that acute microbial toxicity existed in effluents from two out of five plants and acute daphnid toxicity was observed in only one effluent. The result of this study clearly suggests chronic toxicity tests are more suitable to assess biological effects of effluents because it was shown from this study that even an effluent with no acute toxicity could cause chronically lethal and/or sublethal adverse effects on aquatic biota which may affect the population dynamics in aquatic ecosystem.