• Journal of Wetlands Research
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• v.19 no.4
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• pp.501-507
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• 2017

The heavy metal such as Nikel (Ni) in industrial wastewater is one of the major reasons of decreasing nitrification efficiency in municipal wastewater treatment plants (MWTPs). In this study, laboratory scale reactors were operated in order to analyse of nitrification efficiency and improvement measures. As a result, nitrification efficiency during high Ni concentration (0.295 mg/L) was about 20%. However nitrification efficiency during low Ni concentration (0.114 mg/L) was over 70%. The changes of the micro-organism activity according to Ni concentration was investigated as being the major reason behind the gap of nitrification efficiency through analysing AUR and SNR. Increasing the HRT in high Ni concentration also increased the nitrification efficiency. Thus, maintenance of microorganisms and increasing the HRT in nitrification reactors suggests that measures taken to treat wastewater is positively correlated with high concentration of heavy metal.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2004.05a
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• pp.329-331
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• 2004

본 연구에서는 토양을 충진한 컬럼을 사용하여 질산화 반응을 촉진시키기 위한 첨가제에 따른 효과를 검토하였다. 토양만을 충진한 컬럼에서는 $NH_{4-}$/N의 약 26%가 질산화 되었으며 제올라이트를 첨가 하였을 때 실험초기에는 $NH_{4-}$/N가 유출되지 않다가 20일 이후부터 $NH_{4-}$/N의 농도가 증가 하기 시작하였으며 이는 제올라이트에 의한 흡착능력의 저하로 사료된다. 폐굴껍질 20% 충진한 토양컬럼에서는 실험 95일까지 99.7%의 질산화율을 보았다. 위의 결과로부터 알 수 있듯이 토양컬럼에 폐굴껍질과 제올라이트를 첨가제로 충진하였을 경우 질산화 반응을 촉진시켜서 질산화율을 높일 수 있음을 확인 할 수 있었다.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.2
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• pp.191-197
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• 2005

A new method, ToxTemp (TOXcity test based on TEMPerature control) using Ceridaphnia dubia was applied to evaluate the toxicity of insecticide materials and compared with the standard 48 hr acute bioassay. BPMC, diazinon and fenitrothion may cause the inhibition to the biological process in sewage treatment plant and need to detect toxicity within short contact time. The ToxTemp method showed sensitive detection with more shorter contact of 1-1.5 hr time than that of the standard 48 hr acute bioassay. To evaluate toxicity of real wastewater/sewage, the inhibition rate of nitrification and oxygen uptake rate (OUR) using activated sludge, the standard 48hr acute bioassay and ToxTemp method using C. dubia were compared, respectively. On the basis of the inhibition rate of nitrification, the OUR test showed the less sensitive results at the relatively strong toxic sewage. On the other hands, the standard 48hr acute bioassay and ToxTemp method using C. dubia represented the toxicity of each wastewater/sewage with high sensitivity. Even the slightly low (about 1.5%) sensitivity, the ToxTemp method showed the high applicability to the real site of sewage treatment plant.

• Clean Technology
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• v.18 no.4
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• pp.398-403
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• 2012

Selective nitrification and granulation have been carried out in a pilot scale air-lift sequencing batch reactor (SBR) for stable and economical nitrogen removal from wastewater. The SBR showed about 100% nitrification efficiency up to 1.0 kg ${NH_4}^+-N/m^3{\cdot}d$, about 90% efficiency at 1.0-2.0 kg ${NH_4}^+-N/m^3{\cdot}d$, and it was less than 90% when the load was higher than 2.0 kg ${NH_4}^+-N/m^3{\cdot}d$. Nitrite accumulation was induced by selective inhibition of nitrite oxidizing bacteria by free ammonia inhibition and dissolved oxygen limitation. For the purpose, high nitrite ratio (> 0.95) was obtained by keeping the pH higher than 8.0 and dissolved oxygen lower than 1.5 mg/L. In addition, sludge granulation was achieved by keeping reactor settling time to 5 minutes to wash out poor settling sludge and to promote the growth of granulation sludge. The operation accelerated sludge granulation and the sludge volume index (SVI) decreased and stably maintained to less than 75 in 60 days.

• Journal of Wetlands Research
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• v.20 no.4
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• pp.390-397
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• 2018

The Municipal Wastewater Treatment Plant(MWTP), located industrial estate, has a problem of decreasing nitrification efficiency. In this research, it was analyzed that effect of heavy metals and retention time to nitrification based on operational result of laboratory scale reactors. And suggest improving MWTP operation method for increasing nitrification efficiency based on findings. According to operational result, laboratory scale reactor shows over 60% nitrification efficiency over hydraulic retention time(HRT) 0.5 day. However, the nitrification efficiency of S MWTP(high heavy metal concentration) sample was lower than that of A MWTP(low heavy metal concentration) sample in same operational condition. The main reason was heavy metals in industrial wastewater. This heavy metals was acted as inhibitor to nitrifier in reactors. So, activity of nitrifier was analyzed based on specific nitrification rate(SNR). The SNR of S MWTP sample shows 0.13 ~ 0.21 mg NH4/gMLSS/hr and that of A MWTP sample shows 0.74 mg NH4/gMLSS/hr. As a result, the activity of nitrifier of S MWTP was lower than that of A MWPT. In other words, retrofit methods for improving nitrification efficiency in MWTPs located industrial estate were that to increase retention time in biological treatment process or to pretreat heavy metal before being injected biological treatment process.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.3
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• pp.233-237
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• 1998

Mineralization of organic N is an important factor in determining the appropriate rate for organic waste application to cropland. The mineralization of organic N was examined using sandy soil amended with three kind of compost (municipal solid waste+biosolid, yard trimmings, yard trimmings+biosolid), respectively. During the 12-week incubation, the mineralization of organic N was determined by analyzing the inorganic N in leachates from unamended and amended soils. Soils amended with com posts made of biosolid had higher initial $NH_4-N$ concentration than unamended soil. Soil amended with compost made of yard trimmings only had slightly lower initial inorganic N concentration than unamended soil. In the soil amended with com post made of yard trimmings+biosolid, however, nitrification rate was enhanced in the first week of incubation. Net N mineralization and nitrification were positive in all treatments. Although the greatest net N mineralization occurred in the soil amended with compost made of yard trimmings+biosolid, the greatest net mineralization and nitrification rates occurred in unamended soil.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2001.04b
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• pp.67-68
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• 2001

돈분발효퇴와 포도주 부산물의 질소 무기화 및 질산화 과정을 구명하기 위해 시설 내 고추생육시기에 토층별 암모늄태 및 질산태 질소함량을 조사하였다. 질소무기화 및 질산화는 심토층보다 표토층에서 높게 나타났다. 생육전반에 걸쳐 총 질소 무기화 및 질산화율은 처리간에 다양하였지만, 전반적으로 총 질소 무기화는 정식후 90일 까지 증가하였지만 그 이후로는 감소하였다. 표토층에 있어 최고 질소 무기화 및 질산화는 정식후 90일에 T4(포도주부산물 400kg/10a＋돈분발효퇴비 1,000kg/10a)에서 관측되었다. 가장 높은 질소 무기화는 정식후 30일에 대조구에서 272.5mg/kg과 정식 후 90일에 T4(포도주부산물 400kg/10a＋돈분발효퇴비 1,000kg/10a)에서 843.4mg/kg으로 나타났다. 또한 질산화는 T4(포도주부산물 400kg/10a＋돈분발효퇴비 1,000kg/10a)에서 정식 후 90일에 872.2mg/kg으로 가장 높게 나타났다. 15-30cm 토층의 질산화 현상은 질소 무기화와는 다르게 나타났는데 질소 무기화는 대체로 90일에 증가한 반면 질산화는 90일에 감소하는 경향을 나타내었다. 마지막 조사시기인 정식 후 180일에는 급격히 감소하는 현상을 보였는데 고추 생육에 따라 양분 흡수로 암모늄태질소 및 질산태질소가 감소되었다. 0-15cm 토층, 15-30cm 토층의 질소무기화 및 질산화에서 T4(포도주부산물 400kg/10a＋돈분발효퇴비 1,000kg/10a)의 15-30cm 토층 질산화가 낮게 나타났다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.2
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• pp.116-121
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• 2005

Immobilization technique by PVA encapsulation is an effective alternative for wastewater treatment. However little information is available about the effect of PVA characteristics on physical properties as an encapsulation media. This study aims at investigating the effect of the preparation methods of PVA and filler addition to media on the solubility of PVA. The solubility decreased as the freezing temperature decreased and the vacuum-drying was applied. Addition of the PAC (Powered Activated Carbon) and organoclay decreased the solubility of the PVA gels. Organoclay was more effective for lowering the solubility about 25% than the PAC. Nitrification with the PVA-coating media was less sufficient than with the polyurethane media due to the mass transfer restriction for oxygen and nutrients.

• Journal of Korean Society of Forest Science
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• v.84 no.2
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• pp.198-206
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• 1995

The objective of this study was to determine the rate of nitrogen mineralization at clearcut and uncut in oak(Quercus rubra L.) and pine(Pinus resinosa Ait.) stands. The study sites were located in northern Lower Michigan, U.S.A. Nitrogen mineralization rates in the top 15cm of mineral soil were examined during the 1991 and 1992 growing seasons(May-October) using an in situ buried tag technique. diet nitrogen mineralization in oak stands over the course of both growing seasons was 67kg/ha in the clearcut and 30kg/ha in the uncut stands. In contrast, net nitrogen mineralization in pine stands was 27kg/ha and 13kg/ha for the same treatments. Total net nitrogen mineralization rates were always higher in oak stands than in pine stands. Extractable $NO_3^-$ before and after one month soil incubation in both oak and pine stands was generally not detectable in the uncut stands, but in the pine clearcut treatment(nitrification over the course of both growing seasons : 3.3kg/ha). The results indicated that : 1) substantial increases in the amount of available soil nitrogen occurred following clearcuts in both stands : and 2) the loin rates of nitrification may be an important mechanism for retention of nitrogen in both oak and pine stands.

• Journal of the Korea Organic Resources Recycling Association
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• v.22 no.3
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• pp.33-40
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• 2014

This study were conducted to evaluate the N mineralization and nitrification rates and to estimate the losses of total carbon and nitrogen by runoff water in soils cooperated with organic composts and bio-char during corn cultivation. For the experiment, the soil texture used in this study was clay loam, and application rates of chemical fertilizer and bio-char were $230-107-190kg\;ha^{-1}$($N-P_2O_5-K_2O$) as recommended amount after soil test and 0.2% to soil weight. The soil samples were periodically taken at every 15 day intervals during the experimental periods. The treatments were consisted of cow compost, pig compost, swine digestate from aerobic digestion system, and their bio-char cooperation. For N mineralization and nitrification rates, it was shown that there were generally low in the soil cooperated with bio-char as compared to the only application plots of different organic composts except for 47 days after sowing. Also, they were observed to be highest in the application plot of swine digestate from aerobic digestion system. For loss of total carbon by run-off water, it was ranged from 1.5 to $3.0kg\;ha^{-1}$ in the different organic compost treatment plots. However, Loss of total carbon with bio-char could be reduced at $0.4kg\;ha^{-1}$ in PC treatment plot. Also, with application of bio-char, total nitrogen was estimated to be reduced at 4.2 (15.1%) and $3.8(11.8%)kg\;ha^{-1}$ in application plots of pig compost and swine aerobic digestate, respectively.