• Journal of Korean Society of Environmental Engineers
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• v.32 no.7
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• pp.730-737
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• 2010

It is very important to remove fluoride ion before treating semiconductor wastewater containing high concentration of ammonia, phosphates, and fluoride ions by struvite formation. Calcium ion was generally added for the removal of fluoride ion. However, calcium ions remained after removal of fluoride ion can deteriorate the performance of struvite crystalization. It should be removed completely before struvite formation. In this study, the effect of fluoride and calcium ion concentration on the struvite crystalization was investigated. Removal efficiencies of ortho-phosphate with struvite formation were more abruptly decreased than those of ammonium nitrogen, as increase of fluoride ion concentration in synthetic wastewater. The structures of struvite formed in synthetic wastewater containing calcium ion of up to 500 mg/L were identical. Purity of struvite was deteriorated as increase of calcium ion over 500 mg/L. Removal efficiencies of ammonium nitrogen were more decreased than those of phosphate ions as increase of cacium ion in synthetic wastewater.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.5
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• pp.542-548
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• 2005

A fluidized bed reactor containing porous media has been known to be effective for nitrogen and organic matters removal in wastewater. The porous media which attached microbes plays important roles in simultaneous nitrification/denitrification (SND) due to coexistence of oxic, anaerobic and anoxic zone. For SND reaction, oxygen and organic substrates should be effectively diffused from wastewater into the intra-carrier zone. However, the overgrowth heterotrophic microbes at the surface of porous media may restrict from substrates diffusion. From these viewpoints, the existence and effect of heterotrophic bacteria at surface of porous media might be the key point for nitrogen removal. A porous media-membrane hybrid process was found to have improved nitrogen removal efficiency, due to stimulated denitrification as well as nitrification. Microelectrode studies revealed that although intra-media denitrification rate in a conventional fluidized bed was limited by organic carbon, this limitation was reduced in the hybrid process, resulting in the increased denitrification rate from 0.5 to $4.2\; mgNO_3-N/L/hr$.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1B
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• pp.119-124
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• 2006

The purpose of this study was the comparison of pollutants removal and the track study of the nitrogen and phosphorus, the estimation of the nitrification and denitrification rate, and the investigation of the nitrogen mass balance between intermittently aerated membrane bioreactor(IAMBR) and intermittently aerated bioreactor(IABR), thus it verified the validity of the membrane submergence. As a result, it had no difference of organic matter removal, however, IAMBR showed better efficiency than IABR in the nutrients. Also, $NO_3{^-}$-N concentration at the anoxic state in the reactor was lower in IAMBR, and the denitrified nitrogen of IAMBR was 40.9%, that of IABR was 10.7%, thus it found out that the denitrification capability of IAMBR was higher than IABR above fourfold. Therefore, it seems resonable to conclude that the membrane helps to improve the removal of pollutants, because of the high MLSS concentration and the available method of intermittent inflow/outflow.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.1
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• pp.59-63
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• 2016

The objective of this study lies in identifying the applicability of zeolite for the removal of wastewater ammonium and nitrate nitrogens. To this end, the author tracked adsorption variations as seen with the adsorption removal of wastewater ammonium and nitrate nitrogens. As a result, it was indicated that the maximum adsorption of zeolite acting on the adsorption removal of ammonium nitrogen would reach 120mg/g (weight of ammonium nitrogen divided by that of zeolite), and that Langmuir adsorption isotherm explained the adsorption of ammonium and nitrate nitrogens better than Freundlich adsorption isotherm. This means that zeolite makes ion exchanges with adsorbate for unilayer adsorption. It was also indicated that the removal efficiency of ammonium nitrogen with varying pH would be higher in the order of pH7 > pH5 > pH9 > pH3.

• Korean Journal of Environmental Biology
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• v.17 no.1
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• pp.117-124
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• 1999

Nutrients removal by water hyacinth, Eichhornia crassipes (Mart.) Solms from nutrient enriched waters and swinery wastewater were evaluated. The contents of nitrogen and phosphorus of dried water hyacinth increased from 1.4 to 3.3% and 0.21 to 0.80% when water hyacinth available N and P in the culture medium were increased from 0.7 to 5.0 mgN/1 and 0.06 o 1.5 mgP/l. respectively. Maximum N and P contents were found to be 4.1 and 0.90%, respectively. The significant relationship was observed between the standing crop of water hyacinth and the biomass yield per unit area and time. Biomass yield increased gradually until standing crop reached 15 kg wet wt./m$^2$, and then rapidly decreased. The high biomass yield of up to 0.5 kg/m$^2$/day was obtained in the range of 7 to 20 kg/m$^2$of standing crop. The potential removal rates of N and P by the water hyacinth during summer were found to be 2,250 to 2,710 mgN/m$^2$/day and 570 to 595 mgP/m$^2$/day, respectively, when 15 kg/m$^2$in standing crop and nutrient concentrations of culture medium were ranged from 1.24 to 6.2 mgP/1 and 3.2 to 32.5 mgN/1, respectively, Inorganic N and P concentrations of swinery wastewater were in the range of 82 to 121 mgN/1 and 22 to 79 mgP/1, respectively. Nitrogen and P removal rates of water hyacinth cultured in swinery wastewater were found to be in the ranges of 2,000 to 2,600 mgN/m$^2$/day and 157 to 254 mgP/m$^2$/day, respectively, at 10 times diluted water of swinery wastewater.

• Journal of the Korean Applied Science and Technology
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• v.34 no.2
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• pp.217-224
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• 2017

This is a study on the removal of nitrate nitrogen from wastewater by oxidation and reduction reaction of zinc in an acidic atmosphere. The optimum removal rate of nitrate nitrogen and the optimum pH were studied by controlling the amount of zinc and sulfamic acid. The oxidation efficiency was higher at pH 2.0 in the range of pH 2.0 ~ 4.0 because the reaction occurred more strongly in strong acidic atmosphere. It is advantageous to reduce the nitrate ion to the final nitrogen gas by adding the sulfamic acid to the sulfurous acid because it consumes less $H^+$ ion than when the sulfamic acid is not present. According to the same amount of zinc, nitrate nitrogen was removed by 46.0% while sulfamic acid was not added, whereas nitrite nitrogen was removed by 93.0% by adding sulfamic acid. In addition, In this experiment, zinc was prepared in powder form and its reactivity was larger than that of other common zinc metal, so the removal efficiency was very high, about 80.0%, within one minute after the reaction.

• Clean Technology
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• v.15 no.4
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• pp.280-286
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• 2009

To evaluate the feasibility of electrodialysis for nitrate-nitrogen removal from wastewater, the effect of operating parameters on the removal of nitrate-nitrogen was experimentally estimated. The limiting current density (LCD) linearly increased with the nitrate concentration and the flow rate. The time when the nitrate concentration of diluate reached at 20 mg/L was linearly proportional to concentration of diluate, and the concentration of concentrate did not affect the removal rate. Increase in the flow rate gave a positive effect on the removal rate and became insignificant at How rates greater than 1.6 L/min. The removal rate increased with the applied voltage, but the increment in the removal rate decreased as the applied voltage approached the LCD. From the operation of the electrodialysis module used in this research, the flow rate of 1.6 L/min and the voltage corresponding to the 80~90% of LCD were found be the optimum operating condition for the nitrate removal from highly concentrated nitrate-nitrogen solutions.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1400-1404
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• 2006

생물학적 질소, 인 제거 공정(이하 BNR)의 운전에 있어서 최적 유입수의 C/N(COD/TKN)비, SRT 및 온도의 범위 및 정량적 수치 등은 유기물 뿐 만아니라 질소, 인의 처리 효율에 있어서 매우 중요하다. 특히, 외국과 다른 저농도 유기물 특성을 보이는 국내 하수에 대해서는 BNR 공정의 선택과 설계 및 운전인자의 선별이 무엇보다도 중요한 역할을 한다. 본 연구에서는 IAWQ에서 제시한 ASM No.2d를 기초로 하여 만들어진 전산모형인 Envirosim사의 Biowin 프로그램을 시뮬레이션 도구로 활용하여, 국내 하수에 비교적 적용하기 용이한 A2/O 공정과 MUCT 공정에 대한 유기물, 질소 및 인처리 효율을 비교하고 유입수의 C/N와 SRT 및 온도에 따른 질소, 인 처리 특성과 유출수의 거동 등을 파악하였다. 시뮬레이션 결과, 국내 하수에서는 A2/O 보다는 MUCT 공정이 질소, 인 처리효율이 더 크게 나타났다. 온도와 SRT가 일정한 상태에서 C/N비는 7이상에서 TKN과 TP제거효율이 양호하게 나타났고, 온도와 C/N비를 일정한 조건에서는 SRT가 7일을 넘어서면 효율이 급격히 낮아지는 현상을 관찰할 수 있었다. 온도조건 실험에서는 $20^{\circ}C$이하, 특히 국내 하수처리장에 BNR 적용시 설게조건인 $13^{\circ}C$에 근접해서는 TKN의 제거효율은 급격히 떨어지는 반면에 인 제거효율이 상승하는 것으로 나타났다.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2007.05a
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• pp.375-379
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• 2007

폐비닐 여재(Synthetic Waste Polyethylene Media)를 적용한 부착성장식 공정의 유기물 및 질소${\cdot}$인 제거특성에 관한 Pilot Plant 실험 결과 다음과 같은 결론을 얻을 수 있었다. 1) 제거효율은 $RUNI1{\sim}3$에서 $COD_{cr}$ 91.4, 92.4, 93.9%, T-N 56.9, 61.4, 65.1%, T-P는 모든 단계에서 약 45%이상 제거되어 부하변동시에 강한 대처능력을 나타내었다. 2) BOD용적부하 $0.18{\sim}0.40kg/m^3{\cdot}d$, COD용적부하 $0.28{\sim}0.53kg/m^3{\cdot}d$, ${NH_4}^{+}-N$용적부하 $0.12kg/m^3{\cdot}d$을 나타내었다. 3) 도시하수 처리를 위한 생물학적 질소 및 인 제거공법을 본 여재를 이용하여 공정설계시 고려할 사항들과 적절한 대처방법을 다음과 같이 제시할 수 있다. - 1차 침전지에서 유기질소 및 유기인 농도가 높다면 유기질소 및 인 부하량을 감소시키기 위하여 1차 침전지를 설치하되 질소 및 인제거에 유리한 $BOD_5/T-N$, $BOD_5/T-P$를 유지할 수 있도록 체류시간을 1시간미만으로 설계하는 것이 경제적이라고 판단된다. 만일 유기질소와 유기인의 함량이 낮다면 1차 침전지는 제외하는 것이 유리할 것이다. - 여재의 배치는 폭기조에서 용존산소의 균일분포와 슬러지의 적정탈리를 위해 여재를 상하로 배치하거나 또는 여재끼리 일정 간격을 두어 배치하는 것이 바람직하다. 농촌에서의 처분이 문제시 되고 있는 폐비닐을 적용한 본 연구에서의 수처리특성은 기존 하수처리공정에서의 제거효율에 상응하는 처리특성을 나타내었다. 또한 폐비닐 처분의 문제를 해결할 수 있을뿐만 아니라 하수처리시에도 부하변동 등에 강한 대처능력을 나타내어 기존의 하수처리공정에 대체가능성을 나타내었다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.2
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• pp.77-88
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• 1988

This research investigated the effect of COD/N ratio on nitrogen removal, and the use of organics in raw wastewater as a carbon source for denitrification in SBR(Sequencing Batch Reactor) systems. Four laboratory scale reactors were operated in three modes. Only the difference between modes were; Mode I operated in aerated condition during fill while Mode II in anoxic condition and Mode III operated on two fills per cycle in anoxic condition. When COD/N ratio increased, total nitrogen removal efficiencies increased from 8.7 to 57.7 percent in Mode I, from 28.9 to 83.2 percent in Mode II and from 42.7 to 97.8 percent in Mode III, respectively. COD removal efficiencies ranged from 93 to 98 percent throughout the study. SBR operation in Mode III of feeding twice per cycle in anoxic condition was an effective operating method for nitrogen removal and nitrogen concentration in effluent can be estimated using influent COD and nitrogen concentrations.