• 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.

• Journal of Environmental Health Sciences
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• v.34 no.1
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• pp.76-85
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• 2008

Biological nutrient removal (BNR) sludge was added to a sequencing batch reactor (SBR) in the addition ratios of 0%, 20%, 40%, 50% while observing the variation of nutrient removal characteristics and microorganism groups. When the BNR sludge was added in a ratio over 40%, the characteristics of EBPR (enhanced biological phosphorus removal) was shown at the 27 days. However, a distinct BNR was not shown when the addition ratio of BNR sludge was lower than 40%. The organic removal efficiency were shown as 90% in all SBRs irrespective of the addition ratio of BNR sludge. At the 27 days, the phosphorus removal efficiencies were shown as 40%, 55%, 77% and 69%, respectively, according to the addition ratio of BNR sludge. Overall, efficient nitrification and phosphorus removal was shown when the added BNR sludge ratio was over 40%.

• Journal of Environmental Health Sciences
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• v.43 no.6
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• pp.525-531
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• 2017

Objectives: The purpose of this experiment is to better understand the nitrogen and phosphorus removal ratio according to operating conditions in an iron electrolysis system consisting of an anoxic basin, aerobic basin, and iron precipitation apparatus. Methods: Iron electrolysis consists of an iron precipitation reactor composed of iron plates in oxic and anoxic basins. We studied the interrelation coefficient between T-N and T-P removal rates and F/M ratio, and the C/N ratio and BOD removal rate. Results: The F/M ratio and the T-N and T-P removal rate per unit area have interrelation coefficients of 0.362 and 0.603, respectively. The removal rate per MLVSS and the T-N and T-P removal rate per unit area have respective interrelation coefficients of 0.49 and 0.59. Conclusions: The removal rate of T-N and T-P increased with the increasing F/M ratio in the influent, and they also linearly increased in proportion to the C/N ratio of influent and BOD removal rate of the reactor.

• Journal of Korean Society on Water Environment
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• v.18 no.3
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• pp.291-301
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• 2002

In this study, nutrients treatment by sequencing batch reactors(SBR) was performed. Nitrogen and phosphorus removal efficiencies were evaluated by changing SRT and mixing/aeration ratio. Not only nitrogen but also phosphorus removal patterns were investigated through track studies on 1 cycle. As SRT was fixed and mixing/aeration ratio was changed, maximum nitrogen removal efficiency was 87.6% at mixing/aeration ratio 0.67. Phosphorus removal efficiencies were more than 85.5% except no mixing condition. As mixing/aeration ratio was fixed and SRT was changed, nitrogen removal efficiencies were 70.5~79.8%, which represented slight changes, while phosphorus removal efficiencies were 49.0~97.3%, which represented sharply decreasing tendency at less than 20 day. Both phosphorus release rate k and maximum phosphorus release rate $P_{max}/M$ were are decreased as SRT was decreased, but they were not affected by mixing/aeration ratio. It was found that there is a linear relationship between ortho-phosphate uptake and maximum ortho-phosphate release.

• Journal of Environmental Science International
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• v.7 no.5
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• pp.679-685
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• 1998

The Soysauce wastewater removal characteristics of submerged biofilters filled with two filter media respectively were experimentally examined with constant temperature, pH value and variable BOD loading and recirculation ratio. The decreasing order of BOD removal is Netring(random plastic media), cubic wire meshes(plastic module). This is mainly due to the media characteristics such as void ratio, specific surface area and media shapes. The BOD removal ratio decreases with increasing $BOD_5$/ volumetric loading rate, and the loading rate for the BOD removal over 85% is lower than 1.5kg$BOD_5$ 5/$m^3$d for the plastic media of Netring and cubic wire meshes. The $BOD_5$ removal rate increases with the recirculation ratio, but the rate of increase become smaller as the recirculation ratio increases over 20. When $BOD_5$ volumetric loading is 1.5kg$BOD_5$/$m^3$d, the required recirculation ratio to obtain 85% BOD$_{5}$ removal is about 20 for Netring and it was about 30 for cubic wire meshes.s.

• Journal of the Korean Applied Science and Technology
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• v.23 no.2
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• pp.130-136
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• 2006

Theoretical total nitrogen removal efficiency and reactor volume ratio in oxic-anoxic-oxic system can be found by influent water quality in this study. The influent water quality items for calculation were ammonia, nitrite, nitrate, alkalinity, and COD which can affect nitrification and denitrification reaction. Total nitrogen removal efficiency depends on influent allocation ratio. The total nitrogen removal follows the equation of 1/(1+b). Optimal reactor volume ratio for maximum TN removal efficiency was expressed by those influent water quality and nitrification/denitrification rate constants. It was possible to expect optimal reactor volume ratio by the calculation with the standard deviation of ${\pm}14.2$.

• Journal of Environmental Science International
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• v.6 no.4
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• pp.409-415
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• 1997

In order to Investigate the possibility as a simple technique of wastewater treatment for recirculating aquaculture system, the experiment by a biofilter unfit was carried out. The high and stable removal efficiency of nitrogen could be obtained by selecting the optimum recycle ratio and DO concentration. It was found that the proper combination of nitrifacation and denitrfication step in the reactor would be required for increasing the removal efficiency. The extent of nitrogen removal gradually decreased UO the rise of re- cycle ratio since the depression of denitrificatlon by the lack of hydrogen donor. The depression of nitrogen removal was overcome by increasing the CIN ratio In the wastewater. The extent of phosphorus removal was increased slightly with the increase of DO concentration and recycle ratio, but high removal efficiency was not observed. However, the extent of COD removal was not affected by recycle ratio and DO concentration and showed the stable removal of above 90%.

• Journal of Environmental Science International
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• v.11 no.12
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• pp.1261-1265
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• 2002

This study was focused on the investigation of the characteristics of organics and nitrogen removal with the recycle ratio in anoxic/oxic(A/O) packed bed process that consisted of the anoxic reactor and the aerobic reactor. As increasing the recycle ratio by 0.5, 1.0, 2.0, the COD removal efficiency increased by 94.0%, 98.5%, 98.8% respectively. The aerobic reactor showed the perfect nitrification efficiency by 98.5%, 99.2%, 98.0% respectively. The T-N removal efficiency with the recycle ratio, increased by 56%, 67%, 70% respectively. As increasing the recycle ratio by 0.5, 1.0, 2.0, T-P removal efficiency decreased by 62.1%, 57.4%, 51.3% respectively. The process by releasing the stored phosphorus in the anoxic reactor and uptaking the excess phosphorus in the aerobic reactor, occurred well comparatively when recycle ratio is 0.5. But this process did not occur when the recycle ratio is 1.0 and 2.0. And optimum pH of nitrification was about 6~7 and alkalinity decreased as nitrification rate increased. As increasing the recycle ratio in the anoxic reactor, DO concentration and ORP increased.

• Journal of environmental and Sanitary engineering
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• v.11 no.3
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• pp.63-68
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• 1996

This study was to discuss limiting factors influenced on the removal efficiencies of nitrogenous compounds investigated using the polypropyrene media which was to attach microorganism in order to apply the fixed-biofilm process. The main limiting factors are the hydraulic retention time (HRT), C/N ratio, $COD/NO_{3}-N$ ratio and temperature. The hydraulic retention time HRT were 6, 8, 10, 12 hrs and the C/N ratio range was 2.5-9.5. The $COD/NO_{3}-N$ ratio range was 3.2-21.9 and the temperature were 15, 20, 25, 30, $35^{\circ}C$, respectively. The results of this study are summerized as follows. 1. Hydraulic retention time (HRT) to obtain removal efficiencies of T-N higher than 85% had to be 10 hrs above. 2. The removal efficiencies of T-N decreased at C/N ratio from 6.2 to 4.8 in this anoxic-contact aeration system. 3. Denitrification rate decreased at $COD/NO$_{3}$-N$ ratio from 8.0 to 5.0 4. As temperature increased, removal efficiencies of T-N increased.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.9
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• pp.609-613
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• 2014

The aim of this study was effect of N/P ratio on the nutrient removal in the wastewater using microalgae. For this experiment, 1 to 70 various N/P ratio was prepared and used microalgae as Botryococcus braunii in the wastewater. The results of this study were that 1 to 30 of N/P ratio was need for biomass productivity in the wastewater. TN removal was measured 82% for 1 to 30 N/P ratio and 73-78% for 31 to 70 N/P ratio. TP removal in 1 to 20 N/P ratio was determined up to 80%, but over 21 N/P ratio was decreased significantly and was not changed around 22% of TP removal in the 50 to 70 N/P ratio. Therefore, the optimum N/P ratio in the wastewater was 1 to 30 for biomass productivity, TN and TP removal. The correlation ($R^2$) of TP removal and biomass productivity was 0.9126. However, the relationship between TN removal and biomass productivity was not found. The P content in the wastewater was influenced more than that of TN content.