• Korean Journal of Environmental Agriculture
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• v.15 no.4
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• pp.506-519
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• 1996

The water quality in the rural areas is degrading due to a variety of causes such as the increase of the urban sewage and industrial wastes, the disposal of solid wastes, the growth of livestock waste, the growth of leisure facilities, the establishment of agricultural industry estates and etc. The water pollutants are scarce while the effluent is increasing from wide scattered sources. The technology specifically designed for the rural wastes water treatment plant needs to be implemented with improvement of agricultural water quality. 1. An integrated management measures against water pollution sources. The prevention of water pollution is the best measures in the environmental pollution. Hence, the most effective measures needs to be against the sources. Small-scale water treatment plants needs to be constructed in each village in the rural areas. As for the industrial effluent, the effluent discharge needs to be strictly monitored. Government subsidy for the establishment of treatment plant for livestock wastes is necessary. 2. The establishment of national-wide network for agricultural water quality. The network for agricultural water quality have been operated to conserve the agricultural water quality, and to develop management policies by the assessment of water pollution in the rural areas. The results of agricultural water quality network indicates that the water quality is degrading not only around urban areas but also in the distant rural areas, and the water quality at the pumping stations and weirs is worse than that of reservoirs. 3. The legal, systematic, and technical approaches for the agricultural water quality management. The actions currently implemented for the improvement of agricultural water quality involve temporary measures such as the improvement of irrigation facilities. These contingency measures are not effective in the long-term, and sometimes bring secondary pollution. Therefore, integrated measures covering the whole water environment such as the flow, quality, river morphology, aquatic ecosystem, and the surrounding environment, need be invented and implemented. Besides, the legal, systematic, and technical frameworks for the management are not fully established so far. The technology for the treatment of rural water pollution should be refined afterwards, and the research for the development of rural waste water treatment plant should be carried out.

• Journal of Environmental Science International
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• v.20 no.6
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• pp.673-678
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• 2011

Water samples from several wastewater treatment plants and two industry drains in Gyeongsangbukdo were investigated for concentration levels of micropollutants. Samples were taken totally four times from May to November of 2008 and tested for seven factors including pesticide, 1,4-Dioxane and Perchlorate which had been big issues for Nakdong river because of their contaminations. As results, 2,4-D, Alachlor, and BEHA were not detected while BEHP was detected at some sampling sites. 1,4-Dioxane and Perchlorate were also detected in wide ranges from several sampling sites. Therefore, continuous supervising and monitoring systems needed to be invested for proper management for micropollutants since those micropollutants could affect human health and aquatic system with low concentration levels.

• Journal of Korean Society on Water Environment
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• v.28 no.6
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• pp.933-942
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• 2012

The purpose of this study is to evaluate the degree of waterbody impairment according to the flow conditions and present to the appropriate water quality improvement alternatives using observed water quality and flow for Total Maximum Daily Load (TMDL) implementation at 39 unit watersheds the nakdong river basin. Observed water quality data for 7 years are divided into five cumulative flow frequency group and comparing the each observed water quality data and TMDL Target water quality (TWQ) the last evaluate the water quality is impaired group. We found that the cumulative flow frequency group-specific the average excess rate of V group was the highest (32.86%), followed by the IV group (26.04%), group III (23.36%), II group (22.67%), I group (20.70%), the degree of impaired waterbody tended to be inversely proportional to the flow rate. Resulted from cumulative flow frequency group of impaired water quality assessment, 13 unit watersheds are impaired from a group IV and group V affected by point sources. Therefore, improvement of sewage discharge and the initial composition of the riparian buffer zone are needed. Nakbon F, Namkang D and Namkang E within 13 unit watersheds are impaired from group II and III affected by non-point sources. Therefore, application of Best Management Practices (BMPs) is needed for these watersheds. Evaluation of impaired waterbody using Cumulative flow frequency group is able to determine the extent of the judgment to TWQ exceeded by the flow conditions and helps proper setting Standard flow and planning pollutant reduction for TMDL.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.6
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• pp.617-636
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• 2015

The Mokpo coastal waters receive discharges from three artificial lakes(Youngsan, Youngam, Geumho) and other terrigenous freshwater inflows(streams, sewage treatment effluent, fresh groundwater), which exhibit very high concentrations of nutrients and/or organic matters. To understand spatial distributions of nutrients(DIN, DIP, DSi) and other water quality parameters(Chl-a, water temperature, salinity, DO, COD, SS), field surveys were conducted at 10 stations in the Mokpo harbor and adjacent estuaries on May, July, September, and November 2008 within 10 days following discharge events from artificial lakes. In this study, the freshwater flow rate influxed by the operation of sea dike sluice had significant influence on water qualities of the Mokpo coastal waters, although nutrient concentrations in other freshwater sources such as streams, sewage treatment effluent, and fresh groundwater were much higher. As a result of statistical analysis, DIN, COD, and Chl-a had a negative correlation with salinity. Therefore it was shown that discharge extents, time, and nutrients from the Youngsan lake were major impact factors dominating the spatial characteristics of nutrients and other water quality parameters in the Mokpo harbor and adjacent waters. However, despite non-discharge from the Youngsan Lake on September of this investigated period, it was observed that the nutrient addition was taking place in the lower layer of the estuary suggesting nutrient supply through different pathways. This result has emphasized the need to implement the combined assessment about the cumulative impacts on the Youngsan Estuary environment and ecosystem due to freshwater inputs derived from the artificial lakes as well as other terrigenous inflows, or benthic releases.

• Water for future
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• v.15 no.3
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• pp.23-36
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• 1982

The stochastic variations and structures of time series data on water quality were examined by employing the techniques of autocorrelation function, variance spectrum, Fourier series, autoregressive model and ARIMA model. These time series included hourly and daily observation on DO, turbidity, conductivity pH and water temperature. The measurement was made by automatic recording instrument at Noryangjin and Dook-do located in the downstream part of Han River during 1975 and 1976. Hourly water quality time series varied with the dominant 24-hour periodicity, and the 12-hour periodicity was also observed. An important factor affecting 24-hour periodic variation of DO is believed to be photosynthesis by algae. These phenomena might be attributable to periodic discharges of municipal sewage. Noryangjin site showed the more distinct 12-hour periodicity than Dook-do site did, and tidal effect might be responsible for the difference. The water quality, as measured by DO and turbidity, was better in the afternoon compared with the quality in the morning. This change can be explained by the periodic variation of DO, temperature and the amount of municipal wewage discharge. It was also observed that the water temperature at Noryangjin was higher than the temperature at Dook-do. This difference might have been caused by the pollutants that were added to the section between two sites. The correlation coefficients between some of the variables were fairly high. For example, the coefficient was -0.88 between DO and water temperature, 0.75 between turbidity and river flow, and 0.957 between water temperature and air temperature. The lag time of heat transfer from the air to the water was estimated as 24 days. The first order auto-regressive model was appropriate for explaning standardized hourly DO time series. The ARIMA model of (1, 0, 0) type provided relatively satisfactory results for daily DO time series after the removal of significant harmonic value.

• Journal of Environmental Health Sciences
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• v.39 no.5
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• pp.391-407
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• 2013

Micropollutants emerge in surface water through untreated discharge from sewage and wastewater treatment plants (STPs and WWTPs). Most micropollutants resist the conventional systems in place at water treatment plants (WTPs) and survive the production of tap water. In particular, pharmaceuticals and endocrine disruptors (ECDs) are micropollutants frequently detected in drinking water. In this review, we summarized the distribution of micropollutants at WTPs and also scrutinized the effectiveness and mechanisms for their removal at each stage of drinking water production. Micropollutants demonstrated clear concentrations in the final effluents of WTPs. Although chronic exposure to micropollutants in drinking water has unclear adverse effects on humans, peer reviews have argued that continuous accumulation in water environments and inappropriate removal at WTPs has the potential to eventually affect human health. Among the available removal mechanisms for micropollutants at WTPs, coagulation alone is unlikely to eliminate the pollutants, but ionized compounds can be adsorbed to natural particles (e.g. clay and colloidal particles) and metal salts in coagulants. Hydrophobicities of micropollutants are a critical factor in adsorption removal using activated carbon. Disinfection can reduce contaminants through oxidation by disinfectants (e.g. ozone, chlorine and ultraviolet light), but unidentified toxic byproducts may result from such treatments. Overall, the persistence of micropollutants in a treatment system is based on the physico-chemical properties of chemicals and the operating conditions of the processes involved. Therefore, monitoring of WTPs and effective elimination process studies for pharmaceuticals and ECDs are required to control micropollutant contamination of drinking water.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.9
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• pp.533-541
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• 2015

We investigate the Japan's Master Plan of Comprehensive Sewerage System (JMPS) and Lake Biwa basin sewerage and suggest future development direction of the Watershed Sewerage System Maintenance Plan in Korea enforced on February 2, 2013. The JMPS is designed for compliance with the environmental standard for water quality under the Environmental Policy Act. The effluent standards applied in the master plan of Lake Biwa's Sewerage Plan for the Lake Biwa is tougher than the national standards. Therefore the Lake Biwa Baisn Sewerage System was the first in Japan to adopt facilities that perform advanced treatment for nitrogen and phosphorus removal. BOD, SS, T-N and T-P concentrations of discharge water of sewage are 0.9, 0.6, 5.5, 0.06 mg/L, respectively. Especially removal efficiency for BOD is 99.5 percent. It is necessary to study the diversification of the evaluation criteria, cost minimization approach, subsidy system improvement, economic concept of discharge load adjustment system and establishment of basin sewerage concept for the development of the basin sewerage plan in Korea.

• Journal of Wetlands Research
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• v.9 no.1
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• pp.47-60
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• 2007

The rapid development of economy in China at the expense of consuming huge amount of energy and resources, water resource in particular, which has resulted in the production and discharge of increasing amount of wastewater to the water environment. In order to effectively control the increasing water pollution trend, the State Council has stipulated that all the cities with population over 500,000 should reach wastewater treatment rate of 60% by 2005, and all the cities should reach the rate of 60% by 2010, of which Capital Beijing and all the province capital cities and important tourism cities should reach 70% then. By the end of 2005, of the 661 cities in China, 393 have built and operated municipal wastewater treatments with a total number of 790 sets, total treatment capacity of $80.91{\times}106m^3/d$ and total treatment rate of > 48%. Other 73 cities have started the construction of municipal wastewater treatment plants, and other 168 cities have started to prepare, planning and design of wastewater treatment plants. Most of municipal wastewater treatment plants in big cities in China operate normally and perform well with good quality of effluent in terms of wastewater treatment train, but the sewage sludge treatment is usually poor with big problems. It has been found that the small scale WWTPs using activated sludge process in the towns are usually operated and maintained abnormally because of lack of fund, skilled operators and energy. It is therefore suggested that the small scale MWWTPs in small cities and towns adopt appropriate technologies, of which the most available ones are multi-stage ponds, constructed wetlands and the combination of them for further purification and reuse of treated wastewater.

• Korean Journal of Ecology and Environment
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• v.49 no.3
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• pp.187-196
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• 2016

This study was performed to improve the foaming generated in the effluent of wastewater treatment plant from March 2015 to July 2016. The main cause of foaming was air entrainment by an impinging jet and the internal accumulation by the diffusion barrier. Particularly, the foam growth was most active when there is low tide and larger discharge. To solve this problem, we experimented after installing fine mesh screen and the artificial channel device with underwater discharging outlet in the treated wastewater discharge channel and the outlet, respectively. As a result, the effects of foam reduction by devices ranged 85.0~92.0% and 70.7~85.6%, respectively. In addition, the foam and the noise were easily solved, first of all look to contribute to the prevention of complaints. Our device studies were applied to a single wastewater treatment plant. However, it is considered to be able to apply in other similar cases of domestic sewage treatment plants.

• Journal of Korean Society on Water Environment
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• v.33 no.6
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• pp.696-714
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• 2017

Simple material budget models were developed to predict the spring season (March ~ May) water quality for a river-type reservoir Paldang, in the Republic of Korea. These models are available at mixed water bodies whose light intensity is negligible at the bottom. The calculated data from the models fit quite well with field data collected for 30 years, from 1988 to 2017. The apparent settling velocity of total phosphorus was estimated to be $110m\;d^{-1}$. The critical hydraulic load that determines the usability of phosphorus for algal production appeared to be about $2.0m\;d^{-1}$. When a hydraulic load was larger than the critical value, the concentrations of chlorophyll ${\alpha}$ ($Chl.{\alpha}$), chemical oxygen demand (COD), and 5-day biochemical oxygen demand BOD in the reservoir water became insensitive to internal algal reactions. The model analysis showed that the allochthonous COD continued to increase while the allochthonous BOD slightly decreased after 1999. The decrease of allochthonous BOD is due to the expansion of sewage and wastewater treatment plants in the watershed. The increase of allochthonous COD seems to result from the increase in anthropogenic non-point sources as well as the increase in the discharge of natural organic matters due to climate change. Organic matter of algal origin continued to increase until the mid-2000s, but recently it has decreased as the phosphorus concentration has decreased. The COD and BOD of algal origin increased from 35 % and 27 % during 1988 ~ 1994 to 43 % and 40 % during 2000 ~ 2010, respectively, and then decreased to 25 % and 28 % during 2011 ~ 2017.