• Clean Technology
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• v.23 no.1
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• pp.1-14
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• 2017

At high nitrate concentrations, water must be treated to meet regulated concentrations because it results in threat to human health and eutrophication of natural water. However, it is almost impossible to remove nitrate by conventional water treatment methods such as coagulation, filtration and precipitation, due to its high water solubility. Therefore, other technologies including adsorption, ion exchange, reverse osmosis, denitrification, and electrodialysis are required to effectively remove nitrate. Each of these technologies has their own strengths and drawbacks and their feasibility is weighted against factors such as cost, water quality improvement, residuals handling, and pre-treatment requirements. An adsorption technique is the most popular and common process because of its cost effectiveness, ease of operation, and simplicity of design. Surface modifications of adsorbents have been enhanced their adsorption of nitrate. The nitrate-selective membrane process of electrodialysis reversal and reverse osmosis have proven over time and at many locations to be highly effective in removing nitrate contaminating problems in aqueous solutions. Both electrodiaysis and reverse osmosis methods generate highly concentrated wastes and need careful consideration with respect to disposal.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.4
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• pp.228-233
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• 2015

This study was performed to examine the effect of zinc on the biodegradability, nitrification, denitrification and oxygen uptake rate (OUR) using batch reactor and continuous flow stirred tank reactor (CSTR) of anaerobic/anoxic/oxic ($A^2/O$). The results of this study can be summarized as follows. In the case of the effect of zinc on organic treatment, zinc had no effect up to 12 mg/L with batch reactor but biodegradability was lowered when it was above 3.0 mg/L with CSTR. Concerning the case on nitrification and removal of nitrogen, nitrification rate was lowered when zinc was above 6.0 mg/L with batch reactor and removal rate of nitrogen was lowered when zinc was above 3.0 mg/L with CSTR. Removal rate of phosphorus was lowered when it was above 6.0 mg/L zinc with batch reactor and above 3.0 mg/L zinc with CSTR. In the case of OUR, it decreased as microbial activity was affected when zinc concentration was above 3.0 mg/L in CSTR.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.421-421
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• 2021

도시화, 산업화로 인해 하수처리장 유입하수 내 질소 농도가 증가하면서 그에 따른 부영양화 발생, 수생태계에 독성을 미치는 등의 악영향 또한 증가하게 되었다. 하수 내 고농도 질소를 처리하기 위해 1990년 초 연구가 시작되어 현재 보편적으로 사용되고 있는 생물학적 질소 제거 공정은 산소공급과 외부탄소원 보충 과정에서 상당한 비용이 소요된다. 이와 같은 문제점이 대두됨에 따라 고도의 질소 제거 공정이 요구되면서, 경제적으로 개선이 이루어져 기존의 질산화·탈질 공정보다 효율적인 혐기성 암모늄 산화 공정(ANaerobic AMMonium OXidation, ANAMMOX)이 제안되었다. ANAMMOX 공정은 혐기성 조건 아래 전자공여체와 전자수용체로써 암모니아성 질소와 아질산성 질소를 이용해 질소가스 형태로 질소를 제거하는 공정이다. 질산화·탈질 공정과 비교했을 때, 폭기과정에서의 산소요구량 감소, 외부탄소원 불필요, 질소 제거 과정 단축 등의 장점을 가진다. 본 연구는 수처리공정에서의 ANAMMOX 공정의 적용 가능성을 확인하고, 암모니아성 질소대비 아질산성 질소 비율에 따른 Mainstream ANAMMOX 공정의 효율 비교를 통해 공정의 안정성과 높은 제거효율을 확보할 수 있는 NH₄⁺ 대비 NO₂^- 비율을 도출하는데 목적이 있다. 실험실 규모의 Mainstream ANAMMOX 반응조에 적용한 비율은 선행연구를 비롯한 화학양론식에서 제시된 비율을 바탕으로 산정하였다. 1.00부터 1.30의 전체적인 비율을 Initial과 Advanced 2개의 구간으로 나누어 운전한 결과, 각 구간의 NH₄⁺ 제거효율은 각각 58~86%, 94~99%였다. NH₄⁺ 대비 NO₂^- 비율이 증가함에 따라 공정의 안정성이 확보되고, NH₄⁺ 및 총질소(TN) 제거효율이 증가하는 경향이 나타났다. 본 연구의 결과는 수처리공정에서의 안정적인 ANAMMOX 공정 적용을 유도하고, ANAMMOX 공정의 성능개선을 도모하는 연구의 기초로 활용될 수 있다.

• Journal of Korea Water Resources Association
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• v.47 no.3
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• pp.247-256
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• 2014

A company, which is chicken butcherying-plant, was scheduled to increase up to twice output. We researched the way to increase up to twice the processing efficiency at the target biological treatment tank of A company. We performed for this study to obtain the reason why organic matter and nitrogen removal efficiency is increased when MLSS concentration is increased. It's performed at the target of pressure flotation water on SBR system. We performed the research which MLSS was 12,700 mg/L for 30hours (in aerobic condition for 25 hours and in anoxic condition for 5 hours). As a result, the nitrification was happened completely in aerobic condition within 25 hours. Denitrification efficiency was also over 90% when C/N ratio was over 3:1. After the experiment, we changed the concentration of MLSS 5,600 to 12,700 mg/L. In condition MLSS was about 11,000 mg/L and HRT were 30 hours meet the Effluent quality standard.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.895-905
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• 2000

This study was performed to investigate the removal efficiencies of pollutants at various filtration rates and the quality of the filtered water along the depth of filter media during treatment of a BNR process effluent by a dual-media gravitational rapid filtration. The results of the experiments at filtration rates of 200, 300 and 400 m/day using the effluent of a pilot scale 4-stage BNR plant showed that turbidity of the filtered water was below 2.6 NTU, satisfying the Korean standard for water for reuse. Even though the SS removal efficiency deteriorated as the filtration rate increased, the average SS concentration of the filtered water was 1.3 mg/L at all filtration rates. Simultaneous biological nitrification and denitrification was observed with nitrification efficiencies of 17.4, 18.8 and 14.3%, and denitrification efficiencies of 32.3, 27.7 and 21.4% respectively at filtration rates of 200, 300 and 400 m/day. At the latter period of each filtration cycle, the effluent T-P concentration was higher than influent T-P concentration by 6.1 to 21.4% due to phosphorous release under DO-deficient condition.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.2
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• pp.75-83
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• 2014

The present study estimated nitrogen budget of South Korea including nitrogen oxides (NOx) in 2011. Emission sources of NOx were calculated with the higher contributors, such as vehicles, businesses, power plants, based on the IPCC and EPA reports. Moreover, nitrogen budget was separated for city, agriculture livestock and forest. Input and output were chemical fertilizer, crop uptake, fixation, irrigation, compost, leaching, volatilization, imported food, denitrification, runoff, and so on. Annual nitrogen input were 1,692,650 ton/yr and output were 837,739 ton/yr which were increased from 2010 budget. In 2011, NOx emissions by vehicles, power plants, and businesses were 308,207 ton/yr, 601,437 ton/yr, and 469,946 ton/yr, respectively. Including nitrogen oxide, total nitrogen input and output in 2011 was calculated as 5,652,366 ton/yr and 1,425,371 ton/yr, respectively.

• Microbiology and Biotechnology Letters
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• v.39 no.3
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• pp.210-217
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• 2011

In an effort to isolate novel bacteria for the bioremediation of over-fertilized soils, we identified 135 denitrifying cells out of 3,471 oligotrophic bacteria pools (3.9%) using a denitrification medium supplemented with potassium nitrate as the sole nitrogen source. Soil samples were taken from ecologically well-conserved areas, including a mountain swamp around the demilitarized zone (Yongneup), two ecoparks (Upo and the Mujechi bog), and ten representative islands around the Korean peninsula (Jejudo, Daecheongdo, Socheongdo, Baekryeongdo, Ulrungdo, Dokdo, Geomundo, Hongdo, Huksando and Yeonpyeongdo). All of the 135 bacteria produced nitrogen gas from the denitrification medium, and were proved to be nitrate reductase positive by API-BioLog tests. Phylogenetic analysis using 16S rDNA sequences revealed that the 135 bacteria consisted of 44 different genera. Along with the most prominent, Proteobacteria (87.4%), we identified denitrifying bacteria from Firmicutes (9.4%), Actinobacteria (2.4%), and Bacteroidetes (0.8%). Physiological analyses of the 44 representative denitrifying bacteria, under various pH levels, growth temperatures and salt stresses, revealed 12 favorable denitrifying strains for soil bioremediation.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.6
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• pp.720-727
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• 2005

This study was performed to advance nitrogen removal efficiency by employing an single biofilter packed with granular sulfur, which consists of nitrification occurring at upper part and denitrification at lower part of the reactor. Continuos nitrification/denitrification was carried out with different alkalinity sources, which were $NaHCO_3$ and $CaCO_3$(limestone). In the downflow nitrification/denitrification biofilter packed with granular sulfur, first, terms for nitrogen removal was decided. As results, nitrification and denitrification rate with NaHCO3 at 0.85 kg $NH_4^+-N/m^3{\cdot}d$ were accomplished $0.80kg\;N/m_3{\cdot}d$, $0.43kg\;N/m^3{\cdot}d$, respectively. In the sulfur/limestone packed downflow nitrification/denitrification biofilter, sulfur and limestone were mixed packed, preliminary test showed sulfur/limestone mixing ratio was 3:1 and that was ideal. In the result, nitrification and denitrification rate at $0.7kg\;NH_4^+-N/m^3{\cdot}d$ were accomplished$0.65kg\;N/m^3{\cdot}d$, $0.34kg\;N/m^3{\cdot}d$, respectively. In general, employing granular sulfur can be implemented for only denitrification, but this system can accomplish nitrification as well as denitrification in a single reactor even though low carbon concentration was present in influent limiting to nutrient removal process. This biofilter system of limestone and granular sulfur packed together can successfully apply for nutrient removal effectively.

• Resources Recycling
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• v.9 no.4
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• pp.56-62
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• 2000

This study was introduced an amalgamated septic tank system using mineral sintered body was made from non-metallic minerals with a ability being attached or accelerating a vitality of soil microorganism for the effective wastewater treatment. Experimentally, we made an amalgamated septic tank appling anaerobic-aerobic process experimental facilities to two personal houses for handling a residental sewage directly on a small scale from the place of origin. The results are shown as follows; The COD\ulcorner and BOD of effluent were about 10 mg/l after the treatments and T-N removal efficiency was 60-70%. Moreover these results suggested the possibility of denitrification without adding organics and more than 80% of T-P removal also showed the possibility of wastewater treatment biologically.

• Journal of Environmental Science International
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• v.28 no.7
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• pp.607-615
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• 2019

The purpose of this study is to biological treatment of high salinity wastewater using Aerobic Granular Sludge (AGS). In laboratory scale's experiments research was performed using a sequencing batch reactor, and evaluation of the denitrification reaction in accordance with the injection condition of salinity concentration, surface properties of microorganisms, and sludge precipitability was performed. The results showed that the salinity concentration increased up to 1.5%, and there was no significant difference in the nitrogen removal efficiency; however, it showed a tendency to decrease gradually from 2.0% onward. The specific denitrification rate (SDNR) was 0.052 - 0.134 mg $NO_3{^-}-N/mg$ MLVSS (mixed liquor volatile suspended solid)${\cdot}day$. The MLVSS/MLSS (mixed liquor suspended solid) ratio decreased to 76.2%, and sludge volume index ($SVI_{30}$) was finally lowered to 57 mL/g. Using an optical microscope, it was also observed that the initial size of the sludge was 0.2 mm, and finally it was formed to 0.8-1.0 mm. Therefore, salinity injection provides favorable conditions for the formation of an AGS, and it was possible to maintain stable granular sludge during long-term operation of the biological treatment system.