• Journal of Korean Society on Water Environment
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• v.37 no.6
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• pp.425-432
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• 2021

A tidal power plant (TPP) has been in operation since the end of 2011 to improve the water quality of Shihwa Coastal Reservoir (SCR). Tidal mixing rate increased 5.6 times after the TPP operation so that in this study, its effects on water quality was assessed through statistical analysis of long-term water quality monitoring data. It was found that the increased tidal mixing contributed to solving the hypoxia problem in the bottom water by preventing the summer stratification. The analysis also showed that the increased tidal mixing had different effects depending on the relative concentration difference for each water quality substances between the SCR and the outside of SCR. The average concentrations of some substances (chemical oxygen demand, total phosphorus, chlorophyll-a) with higher concentrations than the outside of SCR decreased due to the dilution effect, but the other substances (total nitrogen, dissolved inorganic nitrogen, dissolved inorganic phosphorus) with lower concentrations compared to the outside ones increased on the contrary. Factor analysis also showed a consistent result that the first factor accounting for the water quality was changed from the organic-related substances to the nutrient-related substances after the increased tidal mixing. These results imply that the focus of future water quality management needs shifting from the organic substances to the nutrients, particularly dissolved inorganic nutrients. Considering the effect of inflow seawater on the nutrients, the management area should be extended to cover not only SCR but also a certain area outside of SCR.

• Journal of Korean Society on Water Environment
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• v.30 no.5
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• pp.539-548
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• 2014

This study was carried out to investigate algal community structures and their correlations with environmental factors on five weir areas in the Nakdong River, South Korea. Water qualities, hydrodynamics, meteorological conditions and algal species compositions were observed in studied sites from May 2010 to Dec. 2013. Results showed that average total phosphorus concentration of 2013 was decreased by 52.4% in comparing with that from 2010 to 2011. Chlorophyll.a concentrations were positive significant with water temperature, pH, total phosphorus and total nitrogen, but is not significant with turbidity and suspended solids. Seasonal successions of algae were observed that Stephanodiscus sp. was dominant species with 65.3% of dominant frequency in studied site. Large algal biomass of the low temperature-adapted diatoms were observed during temperature range of $4{\sim}9^{\circ}C$, but large cyanobacterial biomass mainly during high temperature period ranged from $22^{\circ}C$ to $32^{\circ}C$. Microcystis sp. dominated during high water temperature in summer. The yearly correlations of algal biomass with accumulated solar radiations were not significant but seasonal correlations of summer from June to August were significant with correlation coefficient 0.33 (p<0.05). There were not significant correlations between turbidities and algal biomass. Turbidity and suspended solids concentrations were not significant correlation with algal biomass. According to the results, algal communities had strong correlation with water temperature and had partially correlation with solar radiation. For an effective management of algal blooms, water managers should survey with more long-term monitoring of various environmental factors and algal communities.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.3
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• pp.205-225
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• 2021

Due to the large-scale production and use of synthetic chemicals in industralized countries, various chemicals are found in the aquatic environment, which are often termed as micropollutants. Effluents of municipal wastewater treatment plants (WWTPs) have been identified as one of the major sources of these micropollutants. In this article, the current status of occurrence and removal of micropollutants in WWTPs and their management policies and options in domestic and foregin countries were critically reviewed. A large number of pharmaceuticals, personal care products, and industrial chemicals are found in WWTPs' influent, and are only partially removed by current biological wastewater treatment processes. As a result, some micropollutants are present in WWTPs' effluents, which can negatively affect receiving water quality or drinking water source. To better understand and assess the potential risk of micropollutants, a systematic monitoring framework including advanced analytical tools such as high resolution mass spectrometry and bioanalytical methods is needed. Some Western European countries are taking proactive approach to controlling the micropollutants by upgrading WWTP with enahnced effluent treatment processes. While this enahnced WWTP effluent treatment appears to be a viable option for controlling micropollutant, its implementation requires careful consideration of the technical, economical, political, and cultural issues of all stakeholders.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.3
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• pp.28-39
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• 2001

The eco-hydrodynamic model was used to simulation water quality of Kwangyang Bay according to the environmental variation for appropriate water quality management. The mean concentration of COD was 3.3㎎/L, this exceeded the third class of water quality criteria. Waste water discharging loads showed approximately 90% of total pollutant loads. For satisfaction to below 10㎍/L of Chl. a and 2㎎/L of COD, above 35% reduction of present pollutant loads of point sources are needed.

• Journal of Environmental Science International
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• v.29 no.5
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• pp.559-573
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• 2020

The purpose of this study analyzed the overview of corrugated cardboasrd manufacturing industry and then provide direction for improvement. The BREF (BAT reference document) is an important reference for licensees and officer, including the best available techniques for the industry and achievable environmental performance, technical characteristics, and economic information. In the corrugated cardboard manufacturing process, wastewater pollutants are generated throughout the production process, and water is used in the dissociation and aging process. Atmospheric emissions are mostly generated by steam production from boilers and incinerators for the dry process. SO₂, NOx, CO₂, CO, HCl, dust, VOC, and odor were common. In the EU-BREF (European union BAT reference documents) BAT for wastewater have taken up a relatively large proportion. Items of water pollutants in wastewater were common in COD, BOD, N, P, SS, and however EU-BREF had different pollutants such as AOX and salt compared to K-BREF. In order to improve the quality of the K-BREF, it is necessary to devise basic data research method and data acqusitiom method. Consideration should be given to additional environmental management techniques that reflect the emissions characteristics of the corrugated cardboard manufacturing process. In addition, further research is needed to develop methodologies for selecting BATs considering environmental and economic feasibility.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.6
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• pp.535-550
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• 2018

Total organic carbon (TOC) will replace chemical oxygen demand ($COD_{Mn}$) as an effluent water quality standard in public sewage treatment works (PSTWs) from 2021 in Korea. To ensure effective control of TOC in the effluent, investigation was carried out into TOC levels and sewage treatment operation factors in five target PSTWs using anaerobic-anoxic-aerobic ($A_2O$) processes, media, membrane, and sequencing batch reactor (SBR) technologies. TOC removal efficiencies appeared to be 93-96% on average. As a fraction of TOC, biodegradable dissolved organic carbon (BDOC) was reduced from 64% in the influent to 9% in the effluent in these PSTWs. During the investigation, biological treatment processes were applied flexibly for operation factors such as HRT, SRT, MLSS, F/M ratios and BOD volume loads, based on the influent characteristics and design conditions. As a result, we suggest efficient operating conditions in PSTWs by evaluating relationships between TOC removal and operation factors.

• Journal of Korean Society on Water Environment
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• v.33 no.2
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• pp.197-202
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• 2017

This paper aimed to evaluate the test results of acute toxicity on effluent samples which were exempted from applying of ecotoxicity criteria. Total 316 effluent samples which were free from controlling of ecotoxicity regulation, were tested. Ratio of effluent samples which were exceeded the ecotoxicity criteria (TU > 1) indicated 23.7%. This ratio was a little bit higher than previous study (22.7%) on effluent samples which were controlled under ecotoxicity criteria. These results mean that our ecotoxicity management system is not appropriate and applying of ecotoxicity criteria to all effluent samples (82 industry categories) were needed in order to improve our ecotoxicity system. In addition, the same numeric criteria (TU 1 or 2) for all industry categories were proposed in consideration of these results. Ratio of effluent samples which exceeded the ecotoxicity criteria (TU > 1) with D. magna indicated 23.7%. However V. fischeri showed 14.6%. As a acute toxicity test organism, D. magna seemed to be more sensitive than V. fischeri. Ratio of samples which were exceeded TU 1 with D. magna by 24 h exposure period test indicated 35 %, whereas 48 h showed 41%.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.5
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• pp.453-460
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• 2005

Since late 1970s, water quality monitoring had been performed in Korea by various agencies according to their own needs and objectives. Lacking of consistency in principles, such diverse operation has been producing difficulties in management of information on water quality parameters. These difficulties resulted from the fact that the expansion of monitoring networks had been based not on systematic methodology with considerations on scientifically established planning objectives but on personal experiences and subjective judgments in locating monitoring stations. This study aimed, therefore, to develop a selection methodology for locating monitoring stations to provide various informations on water quality to satisfy various monitoring objectives such as understanding short and long term trends of water quality, monitoring violations to water quality standards, identifying external causes and sources affecting water quality changes, supporting utilization of water resources, examining short-term variations in water quality through a concentrated investigation, estimating pollution loads from each unit watershed, supporting water quality modeling, and establishing informative systems for water resources management. Also, we applied the proposed methodology and presented an improved expansion plan for water quality monitoring networks in the Han River.

• Journal of Korean Society on Water Environment
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• v.25 no.1
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• pp.112-119
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• 2009

Based on the study of soil water dynamics, this study is to suggest an advanced stochastic soil water model for future study for drought application. One distinguishable remark of this study is the derivation of soil water dynamic controling equation for 3-stage loss functions in order to understand the temporal behaviour of soil water with reaction to the precipitation. In terms of modeling, a model with rather simpler structure can be applied to regenerate the key characteristics of soil water behavior, and especially the probabilistic solution of the derived soil water dynamic equation can be helpful to provide better and clearer understanding of soil water behavior. Moreover, this study will be the future cornerstone of applying to more realistic phenomenon such as drought management.

• Journal of Environmental Impact Assessment
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• v.28 no.3
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• pp.263-274
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• 2019

The purpose of this study is to examine a monitoring method, management zones, and maintenance strategies for water friendly facilities in urban streams after the completion of ecological restoration projects. Maintenance monitoring items are composed of 'use space& facilities', 'trails& bike roads', 'access', and 'boards'. The evaluation standards of water friendly facilities are 'maintenance conditions', 'safety', and 'usage level' which are rated as 'good', 'moderate', and 'poor'. Through a field survey and evaluation of 15 stream sections in Jeonjucheon,the management levels of each water friendly facility are determined as 'priority maintenance', 'general maintenance', 'maintain/remove', and 'remove'. Based on the evaluation results, management zones and maintenance strategies are proposed for each stream section. As a results, the stream sections of J2, J3, J4, and J9 which have 5 to 9 facilities with 'priority maintenance' are determined as 'intensive management zone'. The stream sections of J5, J6, J7, J8, J11, and J14 which have 1 to 3 facilities with 'priority maintenance' are determined as 'regular management zone'. The stream sections of J1, J10, J12, J13, and J15 which have no facilities with 'priority maintenance' are determined as 'minimum management zone'. The process of monitoring & evaluation system and determining management zones can be applied to establish a systematic maintenance plan for water friendly facilities by participation of governance in the future.