• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.623-628
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• 2000

This study were conducted to evaluate the mass balance of phosphorus and nitrogen with cropping in experimental pot where the mass of input concentration, and fertilization were variable. Four treatments include CSWNF, TWCF, SWNF. And these cases were compared to the control case of tap water irrigation with conventional fertilization (CONTROL). Fertilization were following conventional fertilization , N : P : K = 11kg : 7kg : 8kg. Input water loading was CSWNF (N:48.7g ,P:3.6g), TWCF(7.8g, 0.6g), SWHF(38.8g ,2.9g), TWNF(38.8g, 2.9g ) and CONTROL(0g ,0g) The result is nitrogen decrease rate; TWCF(19.2%), SWHF(14.9%), CSWNF(9.2%) and SWCF(5.6%). phosphorous decrease rate ; TWCF (10%), SWHF(3.7%), SWCF(0.9%) and CSWNF(0.3%).

• Membrane Journal
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• v.14 no.4
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• pp.289-297
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• 2004

In this study, membranes were coupled to a sequencing batch reactor for simultaneous removal of organic matter and nitrogen, and the influences of MLSS (mixed liquor suspended solid) concentration and the sludge loading rate on membrane fouling and bioactivity were investigated. The amount of membrane fouling slightly increased with MLSS concentration at both non-aeration and aeration conditions, but effect of MLSS concentration was more significant at aeration condition. Although the effect of MLSS concentration on membrane fouling was found to be insignificant at low concentration level, extremely low sludge loading, which were generated by the maintenance of large amount of biomass in the reactor, caused severe membrane fouling, and air scouring effect decreased significantly in this condition. Specific bioactivity was constantly reduced as sludge loading rate decreased. In spite of high MLSS concentration over 17,000 mg/L, the activity of the reactor decreased at extremely low sludge loading rate presumably due to the lower oxygen transfer and the competition of biomass to deficient substrate.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.6
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• pp.779-786
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• 1996

The main purpose of this study was to estimate the role of dissolved inorganic nitrogen (DIN) released from sediment and denitrification process in sediment on the nitrogen budget of Hiroshima Bay by means of collecting data on distributions and budgets of nitrogen and phosphorus in the bay, DIN fluxes across sediment-water interface and denitrification rates in the sediments of the same area. The TN : TP and DIN:DIP atomic ratios of the discharged freshwater were about 26 and 21, respectively. The standing stocks in the seawater of the TN : TP atomic ratio varied from 8 to 14 with an annual mean value of 11, while the DIN : DIP atomic ratio varied from 10 to 15 with an annual mean value of 12 in the bay. The residence time of nitrogen and phosphorus were estimated to be about 109 days and 200 days in the bay, respectively. The proportion of DIN released from sediment and denitrification rate to the loading of total nitrogen into Hiroshima Bay were $45\%\;(37\~82\%)\;and\;13\%(0.0\~37\%)$, respectively, and the amount of nitrogen through denitrification process was 6.5 times larger than the outflow of nitrogen from the bay. The results show that DIN released from sediment and denitrification process in sediment play important roles on the nitrogen budget in Hiroshima Bay.

• Korean Journal of Optics and Photonics
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• v.1 no.2
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• pp.169-177
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• 1990

We have constructed the laser system which was consisted of a high voltage pulse poner supply, a rapid high voltage spark gap and the Blumlein transmission line circuit of the multiple parallel plate capacitor type, and have studied the self-preionization effect from this laser system without additional modifications. The value of inductive or resistive loading of the laser oscillator seems to have a significant effect on the preionization. The optimal operational condition of this laser system was obtained at the inductive loading of L = I mtl across the laser tube with the spark gap distance of 6.0 mm. nitrogen pressure of 50 torr, when repetition rate was 70 Hz. Stability was found to be better than 2.0Yo and EIP was 867 V/cm.torr.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.2
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• pp.55-65
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• 1999

AF(anaerobic filter)/BAF(biological aerated filter) system and UASB(upflow anaerobic sludge blanket)/BAF system, of which system effluents were recirculated to the anaerobic reactors in each system, were operated in order to investigate the performance in simultaneous removal of organics and nitrogen in high-strength dairy wastewater. Advanced anaerobic treatment processes of AF and UASB were evaluated on applicability as pre-denitrification reactors, and BAF was also evaluated on the performance in oxidizing the remaining organics and ammonia nitrogen. At system HRTs of 4.0 to 4.5 days and recirculation ratios of one to three, the AF/BAF system could achieve more than 99% of organics removals and 64 to 78% of total nitrogen removals depending upon the recirculation ratio. Although the UASB/BAF system also showed more than 99% of organics removals, total nitrogen removals in the UASB/BAF system were 53 to 66% which are lower than those in the AF/BAF system at the corresponding recirculation ratios. Optimum recirculation ratios considering simultaneous removal of organics and nitrogen and cost-effectiveness, were in the range of two to three. The upflow AF packed with crossflow module media, as a primary treatment of the anaerobic reactor/BAF system, showed better performances in denitrification, SS removals, and gas production than the UASB. Higher loading rate of suspended solids from the UASB increased the backwashing times in the following BAF. Especially, at a recirculation ratio of three in the UASB/BAF system, the increase in head loss due to clogging in the BAF caused frequent backwashing, at least once d day. The BAF showed the high nitrification efficiency of average 99.2% and organics removals more than 90% at organics loading rate less than $1.4KgCOD/m^3/d$ and $COD/NH_3-N$ ratio less than 6.4. It was proved that the simplified anaerobic reactor/BAF system could maximize the organics removal and achieve high nitrogen removal efficiencies through recirculation of system effluents to the anaerobic reactor. The AF/BAF system can, especially, be a cost effective and competitive alternative for the simultaneous removal of organics ana nitrogen from wastewaters.

• Journal of Animal Science and Technology
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• v.49 no.2
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• pp.161-170
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• 2007

A submerged biofilm sequencing batch reactor (SBSBR) process, which liquor was internally circulated through sandfilter, was designed, and performances in swine wastewater treatment was evaluated under a condition of no external carbon source addition. Denitrification of NOx-N with loading rate in vertical and slope type of sandfilter was 19% and 3.8%, respectively, showing approximately 5 times difference, and so vertical type sandfilter was chosen for the combination with SBSBR. When the process was operated under 15 days HRT, 105L/hr.m3 of internal circulation rate and 54g/m3.d of NH4-N loading rate, treatment efficiencies of STOC, NH4-N and TN (as NH4-N plus NOx-N) was 75%, 97% and 85%, respectively. By conducting internal circulation through sandfilter, removal performances of TN were enhanced by 14%, and the elevation of nitrogen removal was mainly attributed to occurrence of denitrification in sandfilter. Also, approximately 57% of phosphorus was removed with the conduction of internal circulation through sandfilter, meanwhile phosphorus concentration in final effluent rather increased when the internal circulation was not performed. Therefore, It was quite sure that the continuous internal circulation of liquor through sandfilter could contribute to enhancement of biological nutrient removal. Under 60g/m3.d of NH4-N loading rate, the NH4-N level in final effluent was relatively low and constant(below 20mg/L) and over 80% of nitrogen removal was maintained in spite of loading rate increase up to 100g/m3.d. However, the treatment efficiency of nitrogen was deteriorated with further increase of loading rate. Based on this result, an optimum loading rate of nitrogen for the process would be 100g/m3.d.

• Korean Journal of Environmental Agriculture
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• v.18 no.2
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• pp.140-147
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• 1999

Since the national land area is small and the fanning land occupies only 24% of total land area in Korea, the promotion of agricultural productivity is urgent. In this process, the application rate of chemical fertilizer, which is the major pollution factor at agricultural non-point sources, has been increasing in every year. The present study examined difference of runoff loading of nitrogen and phosphorus by rainfall intensity(above 100mm, 80-100mm, 50-80mm and 30-50mm). Runoff loading of nitrogen and phosphorus by rainfall intensity has differences under similar rainfall intensity. We are considering that these results were affected by rainfall intensity as well as hydrological condition, soil management, whether or not fertilizer application, cropping, rice straw and plowing.

• Journal of Korean Society on Water Environment
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• v.23 no.1
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• pp.46-51
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• 2007

This research work aims at treating saline wastewater generated from a fish market using four Sequencing Batch Reactors (SBR) operated under different conditions. The effect of C/N ratio (3, 6) and salt concentration (0.5~2%) on organic and nitrogen removal was studied. The synthetic wastewater prepared with glucose ($C_6H_{12}O_6$) as the primary carbon source along with ammonium chloride ($NH_4Cl$) was used in the three reactors. The fill, anoxic, aeration, settle and draw conditions were 2 hr, 4 hr, 4 hr and 2 hr respectively. The fourth reactor was operated at different conditions to investigate the practical feasibility of SBR application to handle fish market wastewater generated in Ulsan city that had fluctuating loading characteristics. Though the unacclimated sludge was initially affected by the salt concentration, the acclimated sludge removed 95% of the organics irrespective of the NaCl concentration and C/N ratio. However, the removal of nitrogen was affected more by C/N ratio than the salt concentration. While handling fish market wastewater, though the organic and nitrogen loading rate were varying between $0.009{\sim}0.259gCOD_{OH}/gVSS/day$ and 0.005~0.034 gN/gVSS/day, the effluent concentrations were far less than the effluent standard of $120mgCOD_{OH}/L$ and 60 mgN/L respectively, except when loading rates were fluctuating and 4 times higher than the average.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.2
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• pp.75-81
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• 1985

Inhibitory effects of ammonium nitrogen on the nightsoil digestion were investigated in this study by using laboratory digesters. Inhibitory effects were observed even at a concentration less than 1.5g/1 $NH_3N$. This would suggest dilution of influent nightsoil would be one of the applicable methods, however, increased microbial washout due to the dilution limited applicable organic loading rate. The study results indicated 1 : 1 dilution would be most likely applicable to minimize inhibitory effect up to a loading rate of $5kg\;COD/m^3/d$.

• Journal of environmental and Sanitary engineering
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• v.17 no.2
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• pp.79-84
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• 2002

This study investigated possibility of the nitrification and denitrification in one counter-current column with the growth of biofilm attached to its media. This experiment was performed through use of the lab scale reactor composed of the column and settler. The column used was packed with the small size of plastic rings called PALL($1.5{\times}1.5{\;}cm$) with a cylindrical shape. Synthetic wastewater was used in the experiment. The loading rates of carbon (C) and total nitrogen (TN) furnished to the reactor were 0.23 to 1.0 kg COD/m3.d and 0.023 to 1.0 kg N/m3.d, respectively. Major factors controlling the removal efficiencies of COD and TN were the different air flux and volumetric loading rates of COD and TN. The experimental results obtained from this study demonstrated that the removal efficiencies of COD ranged from 90 to 95% and those of TN were from 80 to 83% under the N loading rate of 0.035 and $0.058{\;}kg{\;}N/m^3{\cdot}d$, respectively. The patterns of TN removed were distinctively different on the limit of 50cm of column in depth. This indicated that the nitrification and denitrification occurred near the surface zone of and inside the biofilm respectively, upto the 50cm of the column in depth.