• Journal of the Korean GEO-environmental Society
• /
• v.10 no.1
• /
• pp.43-48
• /
• 2009

This study was performed to investigate the characteristics of nutrient removal by Sequencing Batch Reactor (SBR) system, which could achieve high removal efficiencies of nitrogen and phosphorus and make it possible convenient management and operation. In this study, dissolved oxygen (DO), chemical oxygen demand (COD), nitrogen, and phosphorus in SBR system were examined by variation of anoxic-oxic phase repetition in order to optimize an operational method. The 1~4 times of anoxic-oxic phases (Run 1~4) were repeated during 1 cycle operation period. As the repetition frequency increased, it was more difficult to maintain DO condition enough for denitrification. The SBR system showed high COD removal efficiency more than 91% regardless of operational condition. About 68% of nitrogen removal rate was obtained in conditions of 2 or 3 times repetition of anoxic phases, in which NOx-N among discharged total nitrogen account for more than 99%. Approximately 40% of phosphorus was eliminated in the conditions of 1~3 times of anoxic phase repetition.

• Journal of Korean Society on Water Environment
• /
• v.20 no.6
• /
• pp.571-576
• /
• 2004

Since anaerobic/anoxic/oxic process, which is a typical mainstream biological nitrogen and phosphorus removal process, utilizes influent organic matter as an external carbon source for phosphorus release in anaerobic or anoxic stage, influent COD/T-P ratio gives a strong influence on performance of phosphorus removal process. In this study, a bench scale experiment was carried out for SBR process to investigate nitrogen and phosphorus removal at various influent COD/T-P ratio and nitrate loadings of 23~73 and 1.6~14.3g $NO_3{^-}-N/kg$ MLSS, respectively. The phosphorus release and excess uptake in anoxic condition were very active at influent COD/T-P ratios of 44 and 73. However, its release and uptake was not obviously observed at COD/T-P ratio of 23. Consequently, phosphorus removal efficiency was decreased. In addition, the phosphorus release and uptake rate in anoxic condition increased as the nitrate loading decreased. Specific denitrification rate had significantly high correlation with organic materials and nitrate loadings of the anoxic phase too. The rate of phosphorus release and uptake in the anoxic condition were $0.08{\sim}0.94kg\;S-P/kg\;MLSS{\cdot}d$ and $0.012{\sim}0.1kg\;S-P/kg\;MLSS{\cdot}d$, respectively.

• KSBB Journal
• /
• v.23 no.1
• /
• pp.70-76
• /
• 2008

Surface of hydrophobic media was modified to become hydrophilic by ion beam irradiation. Fixed bed biofilm reactors packed with or without surface modification were used to remove organics, nitrogen, and phosphorus from sewage. This system composed of anoxic/oxic cycles to increase the nutrient removal. A cylindrical polyethylene was used as a packing media in this study. With 12 hours of hydraulic retention time (HRT), the reactors with and without surface modification showed 95% and 92% $COD_{cr}$ removal, respectively. Both reactors showed over 95% $COD_{cr}$ removals for a longer HRT of 16 hours. Nitrogen removal ranged 54.8% to 70.2% for the surface modified system and 57.5% to 76.5% for the non-modified system under same condition. Finally, phosphorus removal ranged 59.4% to 69.8% for the surface modified system and 51.3% to 63.4% for the non-modified system under same condition. From this study organics and phosphorus were better removed in using surface modified media and vice versa for nitrogen removal.

• Journal of Korean Society on Water Environment
• /
• v.25 no.2
• /
• pp.322-328
• /
• 2009

The advantage of simultaneous nitrification and denitrification (SND) is to reduce requirement of oxygen as well as tank volume. The fludized media was used in the oxic (aerobic) tank of Membrane-BNR to enhance the efficiency of SND. Nowadays, the interest of applying membrane to the wastewater treatment plant has been increased, which is proved by a lot of research published about the MBR. The Membrane-BNR, consisted of total 5 reactors might be called the compact process by using the fludized media and having short HRT of 6.5 hr. It could attain the further removal of not only the organics but also nutrients such as T-N and T-P. The mode A and B were identified with or without the step feed of influent. The mode A was classified with 3 modes according to the different DO concentration in the fludized media aerobic reactor, and the mode B with step feed was operated with the optimum DO condition. The step-feed was capable of improving TN removal efficiency under the domestic wastewater with the low ratio C/N. On the other hand, the efficiency of SND with the 1.0~1.5 mg/L DO in the oxic media tank was better than the one with below 1.0 mg/L, on which the nitrification did not happen enough, and with above 3.5 mg/L, on which the reduction of anoxic area in the tank happened. It means that the profitable nitrification should be performed prior to the denitrification step. The removal efficiency of nitrogen by SND was about 20% among of total denitrified nitrogen. And some organic carbon consumed could be reduced by the endogeneous denitrification.

• Korean Journal of Ecology and Environment
• /
• v.36 no.3 s.104
• /
• pp.322-335
• /
• 2003

Nutrient fluxes and sediment oxygen demands (SOD) were measured with intact sediment cores collected from three stations in the downstream of Nagdong River. The sediments were subjected to controlled oxic and hypoxic conditions and temperature gradients (from $10^{\circ}C$ to $30^{\circ}C$) of the overlying waters in laboratory batch system. The effect of temperature and labile layer thickness of the sediment on SOD were examined. $PO_4\;^{3-}$ and $NH_4\;^+$ fluxes were elevated above $20^{\circ}C$ and large mobilities were observed when they were coupled with a hypoxic and high-temperature condition. In the well oxygenated conditions, $PO_4\;^{3-}$ fluxes were negative or negligible but $NH_4\;^+$ fluxes ranged from 1.3 mg N $m^{-2}\;hr^{-1}$ to 2.3 $m^{-2}\;hr^{-1}$. Temperature quotients($Q_{10}$) of $PO_4\;^{3-}$ fluxes were 3.7 ${\sim}$ 7.3 ranges to have the most high values. $PO_4\;^{3-}$ and $NH_4\;^+$ fluxes had the logarithmic increase with temperature, while $NO_3\;^-$ was negatively absorbed to the sediment and linearly correlated with the temperature. $SiO_2$ fluxes showed no difference among oxic and hypoxic conditions and sediment texture. The nutrient fluxes would be closely correlated with pore water chemistry of sediments and activated by the top sediment layer composition such as labile organic matters or algal detritus. The ecological implications of the nutrient fluxes were discussed in terms of sources and sinks of nutrients coupled to algal productions in the Nagdong River.

• Economic and Environmental Geology
• /
• v.55 no.6
• /
• pp.727-736
• /
• 2022

Ice wedges are subsurface ice mass structures that formed mainly by freezing precipitation with airborne dust and surrounding soil particles flowed through the active layer into the cracks growing by repeating thermal contractions in the deeper permafrost layer over time. These ice masses characteristically contain high concentrations of solutes and solids. Because of their unique properties and distribution, the possibility of harnessing ice wedges as an alternative archive for reconstructing paleoclimate and paleoenvironment has been recently suggested despite limited studies. It is imperative to preserve the physicochemical properties of the ice wedge (e.g., solute concentration, mineral particles) without any potential alteration to use it as a proxy for reconstructing the paleo-information. Thawing the ice wedge samples is prerequisite for the assessment of their physicochemical properties, during which the paleo-information could be unintentionally altered by any methodological artifact. This study examined the effect of thawing conditions and procedures on the physicochemical properties of solutes and solid particles in ice wedge samples collected from Cyuie, East Siberia. Four different thawing conditions with varying temperatures (4 and 23℃) and oxygen exposures (oxic and anoxic) for the ice wedge sample treatment were examined. Ice wedge samples thawed at 4℃ under anoxic conditions, wherein biological activity and oxidation were kept to a minimum, were set as the standard thawing conditions to which the effects of temperature and oxygen were compared. The results indicate that temperature and oxygen exposure have negligible effects on the physicochemical characteristics of the solid particles. However, the chemical features of the solution (e.g., pH, electric conductivity, alkalinity, and concentration of major cations and trace elements) at 4℃ under oxic conditions were considerably altered, compared to those measured under the standard thawing conditions. This study shows that the thawing condition of ice wedge samples can affect their chemical features and thereby the geochemical information therein for the reconstruction of the paleoclimate and/or paleoenvironment.

• Economic and Environmental Geology
• /
• v.40 no.5
• /
• pp.605-622
• /
• 2007

Elemental, Rock-Eval pyrolysis and isotopic analysis of the core sediments from the northwestern and eastern Ulleung Basin of the East were carried out to identify their geochemical characteristics, spatial and vertical variation and origin of organic matter in Upper Quaternary sediments from the northwestern and eastern Ulleung Basin of the East Sea. TOC, m and TS did not show spatial variation between the sampling locations whereas they showed systematic vertical variation associated with MIS stages related to the sea-level change of the East Sea. It is suggested that these past changes of sea-level influenced the sedimentary depositional environments and/or diagenesis which resulted the patterns observed in this study. Based on the results of TOC/N, TS/TOC, ${\delta}^{13}C_{org}\;and\;{\delta}^{15}N_{org}$ analysis, organic matters in the study area appears to be predominantly originated from the marine algae rather than land plant and deposited under normal marine oxic condition during MIS I and MIS III period, and under euxinic/anoxic condition during MIS II period. TOC/N, ${\delta}^{13}C_{org}\;and\;{\delta}^{15}N_{org}$ have a relatively constant value irrespective of MIS stages, implying that the organic matter source does not change by the sea-level fluctuations. However, the results of Rock-Eval pyrolysis indicates that the organic matter is in immature stage and originated from land-plant (Type III), locating in the immature stage land plant (Type III). Similar differences were reported from other areas such as the Atlantic Ocean, Iberia Abyssal Plain, Mediterranean Sea, suggesting that Rock-Eval method does not exactly reflect the characteristic of immature organic matters. Accordingly, the application of Rock-Eval pyrolysis for delineating the source of immature organic matters should be approached with caution and all other geochemical proxies should be considered altogether at the same time.