• Journal of Environmental Science International
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• v.17 no.11
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• pp.1265-1271
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• 2008

Aerated submerged bio-film (ASBF) pilot plant has been developed. The presented studies optimized an inexpensive method of enhanced wastewater treatment. The objectives of this research were to describe pilot scale experiments for efficient removal of dissolved organic and nitrogen compounds by using ASBF reactor in plug-flow reactor (PFR) and improve understanding of dissolved organic matter and nitrogen compounds removal rates with dynamic relationships between heterotrophs and autotrophs in the fixed-film reactor. This research explores the possibility of enhancing the performance of shallow wastewater treatment lagoons through the addition of specially designed structures. This direct gas-phase contact should increase the oxygen transfer rate into the bio-film, as well as increase the micro-climate mixing of water, nutrients, and waste products into and out of the bio-film. This research also investigated the efficiency of dissolved organic matter and ammonia nitrogen removals in the ASBF. As it was anticipated, nitrification activity was highest during periods when the flow rate was lower, but it seemed to decline during times when the flow rate was highest. And ammonia nitrogen removal rates were more sensitive than dissolved organic matter removal rates when flow rates exceeded 2.2 L/min.

• Journal of Environmental Science International
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• v.29 no.5
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• pp.531-539
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• 2020

To understand the composition, quantity, and quality of Suspended Particulate Organic Matter (SPOM) in the Gangneung Namdae Stream, Korea, we examined spatiotemporal variations in water temperature, salinity, chlorophlly a (Chl a), Particulate Organic Carbon (POC) and nitrogen (PON), and carbon stable isotope (δ¹³C) of SPOM at six stations in June (pre-monsoon), July (monsoon), and September (post-monsoon) 2017. With increasing precipitation, the average POC and C/N values increased significantly in July than in June. In September, the values decreased with decreasing precipitation. The δ¹³C values showed irregular spatiotemporal fluctuations among the stations and periods, thereby suggesting a greater contribution of autochthonous organic matter to the pool of SPOM than that of allochthonous organic matter derived from upstream. In addition, the large and irregular changes in POC, C/N ratio, C:Chl a, and δ¹³C compared to that of PON were observed for all periods among the stations, indicating a serial discontinuity of the stream. Our results suggest that the Gangneung Namdae Stream is significantly influenced by the increase in freshwater discharge caused by heavy rainfalls during the summer monsoon and post-monsoon periods.

• Journal of Environmental Science International
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• v.32 no.6
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• pp.465-475
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• 2023

In this study, we evaluated the treatment efficiency of livestock wastewater by altering the current density using boron-doped diamond (BDD) electrodes. As the current density was adjusted from 10 to 35 mA/cm2, the removal efficiency of organic matter increased from 22.2 to 71.5%. Similar to that of organic matter, the removal efficiency of color increased with increasing current density up to 85.7%, indicating a higher removal efficiency for color than that of organic matter. The removal efficiency of ammonia nitrogen increased from 14.6 to 53.3% as the current density increased, but it was lower than that of organic matter. In addition, the removal of organic matter, color, and ammonia nitrogen followed first-order reactions, according to the reaction rate analysis. The energy consumption ranged from 4.87 to 8.33 kWh/kg COD, and it was found that the organic matter removal efficiency was more efficient at high current densities. Based on various analyses, the optimal current density was 20 mA/cm2, and the corresponding energy consumption was 6.824 kWh/kg COD.

• Journal of environmental and Sanitary engineering
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• v.13 no.2
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• pp.57-65
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• 1998

In this research, Effect of C/N ratio on nutrient removal in intermittently aerated activated sludge system(IAASS) was investigated with dormitary, building and swine wastewater. Three types (2-stage, 4-stage, modified) of IAASS were operated. Time interval of aeration/nonaeration in IAASS was 1hr/1hr. In treatment of Dormitary wastewater(BOD/T-N ratio : 4.4), Building wastewater (BOD/T-N ratio : 3.14) and swine wastewater(BOD/T-N ratio : 3.84), Nitrogen removal efficiency of 80, 70 and 90.4% was achieved, respectively. Nitrogen removal in IAASS was a great influenced on influent C/N ratio, efficient nitrogen removal was achieved at BOD/T-N ratio over 4. In IAASS operation, $\Delta $BOD mg/L/$\Delta $ nitrogen mg/L ratio was about 4-6. Simultaneous removal of organic, nitrogen and phosphorus in IAASS can achieved. And influent organic was efficiently utilized in denitrification. IAASS could be one of the best alternative process for the retrofit of conventional activated sludge system for the removal of nutrients.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.1
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• pp.40-48
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• 2017

In this study, we evaluated the nitrogen (N) mineralization potential and Nitrogen use efficiency (NUE) of oil-cake, compost, hairy vetch and barley, which are the most widely used organic amendments in South Korea. The N mineralization potential (No) for organic fertilizers treated soil was highest for the hairy vetch treatment with a value of $18.9mg\;N\;100\;g^{-1}$, followed by oil-cake, barley and compost. The amount of pure N mineralization potentials in hairy vetch, oil-cake, barley and compost treatments were 8.42, 7.62, 3.82 and $3.60mg\;N\;100\;g^{-1}$, respectively. The half-life ($t_{1/2}$) of organic N in soil amended with oil-cake fertilizer mineralized quickly in 17 days. While, $t_{1/2}$ values of organic N for the compost and barley treatments accounted to 44.4 and 44.1 days, respectively. Oil-cake was good in supplying nutrients to plants. Compost and barley inhibited plant growth in the beginning growth stage and this is attributed to N immobilization effect. The results of this study highlight that compost and barley could be used as potential slow release fertilizers in conventional agriculture.

• Journal of environmental and Sanitary engineering
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• v.17 no.3
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• pp.46-51
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• 2002

This study was performed to treat a sewage at the upper stream of dam using modified sequencing batch reactor, During the operating period, average $COD_{cr}$, removal efficiency was about 85% but average T-N and ${PO_4}^{3-}-P$ removal efficiencies were 43% and 30% respectively. Because the organic matter was very low compared with nitrogen and phosphorous in influent($BOD_{5}/{NH_4}^{+}-N{\;}={\;}2,{\;}BOD_{5}/{PO_4}^{3-}-P{\;}={\;}15.6$), nitrogen and phosphorus removal efficiency was relatively low. Average nitrogen removal efficiency was 50 % at $10^{\circ}C$ or above and it was 36 % at $10^{\circ}C$ or below. As reactor was located in outdoor without any thermostat, temperature decreased at least $2.4^{\circ}C$ in the winter season. Therefore, if we would apply this modified sequencing batch reactor to sewage which concentration of organic matter was very low compared with nitrogen and phosphorous, we have to addition of external carbon and installation of any thermostat.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.1009-1016
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• 2012

The purpose of this study was to determine the effects of organic fertilizers on soil properties and growth and quality of melon. Organic fertilizer was applied in soil at the rate of 0, 0.5, 1, 2N according to Rural Development Administration guideline in Korea. The fertilizer had no effects on plant growth-rate parameters, including plant height, leaf number, and leaf size. There were minor effects on the fruit quality parameters such as fruit weight, fruit length, fruit width, placenta and seed weights, sugar content, and starch content. Ascorbic acid level was decreased as fertilizer level was increased. The level of nitrate in groundwater increased with increased levels of N.

• Korean Journal of Soil Science and Fertilizer
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• v.11 no.3
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• pp.175-194
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• 1979

The soil organic matter contents in arable land are generally low in Korea. Thus it is generally agreed that the application of organic materials to soils would be much beneficial. Present paper is a review on the effectiveness of organic mat ter application in uplands and lowlands. 1. The effect of organic matter application in uplands are of more clear and simple to explain as compared to that in lowlands. In uplands, appropriate application of organic matters such as compost and various crops residues improves the physical properties of soils leasing to increased water holding capacity, better aeration, and decrease in soil erosion. 2. In lowland, rice soils under water logged conditions the effect of organic matter application on rice yield is not straight borward and demands more refined knowledges for the interpretation of it. 3. It is found that the application of compost in rice soils is more effective when nitrogen fertilizer application is limited it dicating that nitrogen contained in the organic maerials can become available to rice plant and plays an important role for increased yield of rice under the condition where nitrogen fertilizer supply is limited. 4. Application of organic matter does not always bring about the desirable effects. Very often the organic matter application results in more intensive soil reduction leading to the accumulation of harmful substances which would can cancel out the positive effects of organic matter. This is partiunlarly true in poorly drained soils. 5. Rice straw or compost, when applied rice soils, supply sizeable amounts of available silicate to rice plant resulting in yield increase. 6. Although the effectiveness of organic matter application on rice yield in short term experiments is not consistent due to many reasons, the long term effect of organic matter is significant. 7. The term of the $O.M/SiO_2$ ratio in rice soils can serve as a criterion for the judgement of whether organic matter or silicate fertilizer is needed to be applied in a certain soil.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.3
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• pp.153-157
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• 2008

This study was conducted to select some effective organic materials for supplying mineral nutrients at the later red-pepper growing period under organic farming system, and to evaluate the application effect. Nutritional characteristics of organic materials, nitrogen release pattern during liquefying the selected organic materials, and crop growth were examined. Among 18 organic materials, meals such as soybean, rapeseed, cottonseed, and sunflower seed except for gluten had greater nitrogen content. Total nitrogen content liquefied solution of the mixture of organic materials and molasses or yogurt was measured after 7 days of the liquefying, thereafter, the mixture of rapeseed meal and yogurt showed the highest nitrogen, reaching about $3,000mg\;L^{-1}$. Selected liquid manure, mixture of rapeseed meal and yogurt, was applied 8 times to red-pepper plants with fertigation or foliar application. Total nitrogen of leaves at 150 days after transplanting was the highest (4.4%) in the treatment of foliar application of the selected liquid manure, whereas shoot dry weight and fresh fruit yield were the greatest in the treatment of fertigation.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.1
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• pp.44-49
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• 2008

Sufficient inorganic nitrogen supply for crop growth is crucial for economically sustainable organic farming. The effects of an application of cover crop biomass on crop growth, nitrogen utilization and carbohydrate composition were investigated during early stage. Short-term changes in soil nitrogen after incorporating fresh hairy vetch and rye shoots were measured. The inorganic nitrogen from cover crops reached the peak at 15 ($NH_4-N$) and 24 ($NO_3-N$) days after incorporation, and then decreased rapidly. The highest concentration of soil nitrate showed at 27 days of incorporation in hairy vetch and at 18 days in rye, and three fold differences exhibited between two treatments. Crop growth under hairy vetch or rye incorporation significantly differed. At 20 DAT, dry matter production in NPK and hairy vetch was about two fold greater than that in rye. Difference in decomposing rates of hairy vetch and rye had also influence on nitrogen status in leaves and roots of pepper plants. Total nitrogen was greater in NPK and hairy vetch than in rye until 20 DAT, whereas inorganic nitrogen (nitrate and nitrite) concentration was higher in rye. Temporal changes in soluble sugars and starch in pepper plants among treatments were similar, although difference in the amount existed. It was suggested that hairy vetch as an alternative nitrogen source promoted crop growth and mineral utilization during early growth stage, whereas an obvious effect in rye was not found.