• Journal of Environmental Science International
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• v.12 no.1
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• pp.55-61
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• 2003

This study was carried out to obtain the operating characteristics of SMMIAR process for biological nitrogenㆍphosphorus removal. SMMIAR was operated at HLR(Hydraulic loading rate) of 39.6, 52.8, 63.4 and 79.2 $\ell$/$m^2$/d respectively and the operating parameters such as intermittent aeration time ratio of aerobic/anoxic, DO and microorganism concentration were changed to confirm the optimum operating condition. The concentrations of the wastewater BOD, TN(Total nitrogen) and TP(Total phosphorus) were 150, 30 and 7.5mg/$\ell$ respectively. Achieving better removal efficiencies of BOD, TN and TP up to 90, 85.4 and 95.4% respectively, we must keep in operation condition of SMMIAR by 0.75 of time ratio of aerobic/anoxic and by minimum 45 minutes of oxic period simultaneously.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.2
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• pp.99-108
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• 2007

The purpose of this study was to investigate characteristics of concentrations of pollutants such as TN (Total Nitrogen), TP (Total Phosphorus) and COD (Chemical Oxygen Demand) in outflow from a nonpoint source dominated watershed ($6.7km^2$). Regular flow measurement and water sampling were taken at five-day intervals during two years (February 2002 to January 2004) in the Ingyeong River, a tributary of the Han River. The mean concentrations of pollutants during rainy days were significantly (p<0.05) higher than those during dry days. For dry days, the flow-weighted mean concentration (0.06 mg/L) of TP during paddy irrigation periods were higher than that (0.02 mg/L) during non-irrigation periods. The seasonal mean concentration of TN was highest in spring likely due to nitrogen fertilization, but those of TP and COD were highest in summer due to particulate phosphorus and sediment-associated organic matter caused by increased discharge. The pollutant concentrations significantly increased with discharge, suggesting that the measures to reduce the increase in the concentrations during storms are needed to control nonpoint source pollution.

• Environmental Engineering Research
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• v.24 no.4
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• pp.582-590
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• 2019

Currently, the waterfront facility was constructed in New Songdo City, South Korea. It has the various water leisure areas and especially an artificial urban canal with filtered seawater by re-circulating flow system. However, due to excessive amount of nutrients from seawater combined with complicated geometry, it is highly vulnerable to deterioration of water quality. In this study, flow characteristics and pollutant transport were analyzed with comprehensive numerical models, MIKE 3 FM and ECO-lab. Based on these numerical results, notable sampling points were selected for field measurements and comparison between modeling and measured results were conducted. In addition, the integrated water quality evaluation index, Water Quality Index was applied to analyze various water quality issues. We also set up scenarios to control the two kinds of water quality factors, dissolved oxygen (DO), and total phosphorus (TP). As a result, the effect of 20% reduction of TP was less than 10% and it was almost ineffective for a year but it was reduced by up to 40% in case of scenario which DO is increased by 20%. Therefore, it was recommended to control the DO concentration, usually by applying re-aeration facility, rather than TP in artificial urban canal with seawater.

• KCID journal
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• v.3 no.2
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• pp.11-19
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• 1996

Lake Soyang, the largest man-made lake in Korea, has been experiencing water quality degradation because of excessive nutrient loads from the watershed. Objective of this paper is to describe land uses in and TP and TN loading characteristics from the lak

• Korean Journal of Ecology and Environment
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• v.35 no.4 s.100
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• pp.249-256
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• 2002

The variation of trophic state was measured in a reservoir (Lake Andong, Korea) from 1993 to 2000. Phosphorus loading from the watershed was estimated by measuring total phosphorus concentration in the main inflowing stream (the Nakdong River). Phosphorus discharge from the pen-type fish farms was estimated from the amount of fish feed and the rate of phosphorus excretion per feed weight. The transparency in summer was about 2.0 m in 1993 and 1994, but it decreased to about 1.2 m in 1997 and 1998, and recovered to about 2.3 m in 1999 and 2000. TP increased from $11-30\;mgP/m^3$ in 1993 to $18-42\;mgP/m^3$ in 1998, but recovered to $8-13\;mgP/m^3$ in 2000, whereas TN decreased slightly from 1.81-2.96 mgN/L in 1993 to 1.17-1.80 mgN/L in 2000. TN/TP ratios decreased from 82-281 in 1993 to 21-143 in 1998, but again increased to 101-209 in 2000 due to the decrease of TP. The average chlorophyll-a concentration in growing season was in the range of $4.8-16.2\;mg/m^3$ from 1993 to 1997, but it decreased to $3.7-5.2\;mg/m^3$ after 1998. Trophic State Index had shown a gradual increase until 1996, and since then it has declined. The major cause of the trophic state recovery is thought to be the removal of fish farms in April 1998.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.4
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• pp.21-31
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• 2015

The aim of this study is to determine the removal efficiency of total nitrogen and phosphorus from treated swine wastewater by Phragmites australis and Miscanthus sacchariflorus var Geode Uksae-1, and to determine its biomass total energy value and biomethane potential. Plants were grown with a bedding mixture either soil and sand or soil, sand, and bioceramic. Treeated swine wastewater with Total nitrogen (TN) and Total phosphorus (TP) of 222.78 mg/L and 66.11 mg/L, respectively, was utilized. The TN and TP removal is higher in the bio-ceramic-soil-sand bedding media treatment. The highest TN removal of 96.14% was performed by Miscanthus sacchariflorus var Geode Uksae-1, but the elemental analysis shows that Phragmites australis contains more nitrogen than Miscanthus sacchariflorus var Geode Uksae-1, indicating higher nitrogen uptake. The highest TP removal of 98.12% was performed by Phragmites australis. The cellulose content of the plant grown with the bioceramic-soil-sand bedding was approximately 3-6% higher than that of the plant grown in the soil-sand bedding. Different growing substrates may have an effect on the fiber content of plants. The biomethane potential of the produced biomass of the plants was between 57.01 and $99.25L-CH_4/kg$ VS. The lignin content is believed to inhibit the breakdown of plant biomass, resulting in the lowest methane production in the Phragmites australis grown in the soil-sand bedding media.

• Korean Journal of Ecology and Environment
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• v.42 no.4
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• pp.432-440
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• 2009

During the period of past fifteen years (1992~2006), variations of chlorophyll a in relation with water quality in freshwater reservoirs were investigated. This study compared total nitrogen (TN), total phosphorus (TP), chlorophyll a, Secchi depth (SD) and total suspended solids (TSS) between terrestrial freshwater reservoir and coastal freshwater reservoir systems based on their location. Regression analyses (linear and non-linear regressions) were applied for all study sites to examine relationship and interaction of these factors in the freshwater systems from in-land to coasts. The results demonstrated that chlorophyll a was significantly correlated to total phosphorus ($R^2=0.94$, P<0.0001) and was remarkably related to TSS increase ($R^2=0.63$, P<0.0001) in the selected reservoirs. The TN : TP ratio in the reservoir systems was higher than Redfield ratio (16 : 1) indicating that the reservoirs are potentially experiencing P limitation. Water quality of coastal freshwater reservoir system was more significantly decreased than the reservoirs located in in-land during the past fifteen years. The strict management of nutrient discharge into freshwater systems should implemented in the coastal reservoirs since the freshwater is introduced into coastal estuarine systems.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.2
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• pp.99-110
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• 2005

Characteristics of concentrations of total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD) pollutant in percolated water at four paddy field sites (Soro, Odong, Munui, and Boeun) were investigated by a nonparametric test. Percolation rate measurement and percolated water sampling were taken during irrigation periods at $5{\sim}10$ day intervals. The normality of percolation rate and pollutant concentrations were examined using histogram, boxplot, and the Kolmogorov-Smirnov (K-S) test. Pollutant concentrations in percolated water showed positively skewed distribution. The median concentrations of pollutant were 1.91 mg/L for TN, 0.021 mg/L for TP, and 6.6 mg/L for COD, which were lower than its arithmetic mean concentrations by $35\%$ for TN, $36\%$ for TP, and $13\%$ for COD. The median concentrations of TN and TP differed significantly among sample sites according to the Kruskal-Wallis test. However, median concentrations were not significantly different among month except for TN and TP of Soro and COD of Odong. The percolation load of pollutants during irrigation periods in the study area were estimated at $3.12{\sim}7.75\;kg/ha$ for TN, $0.033{\sim}0.155\;kg/ha$ for TP, and 10.7 kg/ha for COD, which were much lower than respective values reported in Japan.

• Environmental Engineering Research
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• v.19 no.3
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• pp.223-228
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• 2014

We investigated seasonal algae variability and its influence on water quality in an agricultural reservoir. We observed that maximal total phosphorus (TP) loads were 1,715 kg from farmland in September, which changed the ecosystem in the reservoir. At this time, Dictyosphaerium pulchellum as green algae dominated. Aulacoseira ambigua as diatom became the most dominant from November 2010 to May 2011. The diatom was sensitive to water temperature. Microcystis spp. and Oscillatoria spp. as cyanobacteria were dominant during summer and fall, and sank down to the sediment during winter and spring. Increasing water temperature during summer causes anaerobic conditions in the sediment, leading to regrowth of cyanobacteria. With regard to the ratio of total nitrogen (TN) to TP, green algae and cyanobacteria were dominant at TN:TP ratios less than 20-30. Diatoms were dominant at TN:TP ratios greater than 30-40. Statistical analysis indicated that diatom growth was dependent on water temperature and TN concentration. TP concentration and water temperature were the key factors for the growth of cyanobacteria and green algae. From these results of this study, the management of land-use was an important parameter for improving water quality in the agricultural reservoir.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.2
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• pp.51-57
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• 2009

The purpose of this study was to investigate characteristics of behavior of nutrients such as TN (Total nitrogen), TDN (Total dissolved nitrogen), TP (Total phosphorus) TDP (Total dissolved phosphorous) in runoff water from a nonpoint source dominated watershed ($6.67\;km^2$). Regular and intensive flow measurement and water sampling were taken during two years (February 2002 to January 2004) in the Ingyeong River, a tributary of the Han River. The mean concentrations of nutrients during rainy days were significantly (p < 0.05) higher than those during dry days. The mean TDN/TN ratio in rainy days (95%) is almost identical to that in dry days (96%), but mean TDP/TP ratio in rainy days (24%) significantly decreased compared with that in dry days (66%), suggesting that dominant form of TP is shifted from dissolved form to particulate form. Accordingly, the measures (.eg. filter strips, cover crops) to reduce soil erosion for fallow upland in the rainy season should be taken to control particulate phosphorous.