• 상하수도학회지
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• 제22권6호
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• pp.673-679
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• 2008

The representative microorganism of autotrophic denitrification using sulfur granule, oxidizes the reduction from S and performs denitrification by reducing $NO_3{^-}-N$ to $N_2$ gas. The sampling of autotrophic denitrification microorganisms has been performed from foreshore sludge, condensed sludge, and active sludge, but the analysis of autotrophic denitrification microbial community characteristics has been lacking. Based on the separation and identification of each sample using the PCR and DGGE methodologies, many types of sulfuric microorganisms and autotrophic denitrification microorganisms were found.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2007년도 학술발표회 논문집
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• pp.46-52
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• 2007

As flue gas desulfurization (FGD) wastewater contains high concentrations of nitrate and is very low in organic carbon, the feasibility of nitrate removal by autotrophic denitrification using Thiobacillus denitrificans was studied. This autotrophic bacteria oxidizes elemental sulfur to sulfate while reducing nitrate to elemental nitrogen gas, thereby eliminating the need for addition of organic compounds such as methanol. Owing to the unusually high concentrations of dissolved salts $(Ca^{2+},\;Mg^{2+},\;Na^+,\;K^+,\;B^+,\;SO_4^{2-},\;Cl^-,\;F^-,)$ in the FGD wastewater, extensive laboratory-scale and pilot-scale tests were carried out in sulfur-limestone reactors (1) to determine the effect of salinity on autotrophic denitrification, (2) to evaluate the use of limestone for pH control and as source of inorganic carbon for microbial growth, and, (3) to find the optimum environmental and operational conditions for autotrophic denitrification of FGD wastewater. The experimental results demonstrated that (1) autotrophic denitrification is not inhibited up to 1.8 mol total dissolved salt content; (2) inorganic carbon and inorganic phosphorus must be present in sufficiently high concentrations; (3) limestone can supply effective buffering capacity and inorganic carbon; (4) the high calcium concentration may interfere with pH control, phosphorus solubility and limestone dissolution, hence requiring pretreatment of the FGD wastewater; and, 5) under optimum conditions, complete autotrophic denitrification of FGD wastewater was obtained in a sulfur-limestone packed bed reactor with a sulfur:limestone volume ratio of 2:1 for volumetric loading rates up to 400g $NO_{3^-}N/m^3.d$. The interesting interactions between autotrophic denitrification, pH, alkalinity, and the unusually high calcium and boron content of the FGD wastewater are highlighted. The engineering significance of the results is discussed.

• 상하수도학회지
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• 제18권2호
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• pp.121-127
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• 2004

It is necessary to supply external carbon source for enhancement of biological nitrogen removal from domestic wastewater with low influent C/N ratio. Sulfide was chosen as a cost effective electron donor and reaction stoichiometry for autotrophic denitrification was investigated by conducting bench-scale experiments in this study. Higher sulfur to nitrogen (S/N) ratio than the calculated value from theoretical reaction stoichiometry was required when the anoxic reactor was operated at open condition because dissolved oxygen introduced by surface aeration reacted with sulfide with ease. In addition, higher sulfate production and lower yield of microorganism could be observed under the same condition. It was possible to obtain reliable reaction stoichiometry for autotrophic denitrification by establishing pure anoxic condition. Linear relationship between bacterial growth and consumption of nitrate, sulfide, alkalinity, and sulfate production enabled to derive a relatively correct reaction stoichiometry for autotrophic denitrification when sulfide was used as an electron donor.

• 상하수도학회지
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• 제22권2호
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• pp.259-265
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• 2008

Generally speaking, there are two widely used methods of Nitrogen removal from waste water: 1) nitrification using autotrophic microorganisms, and 2) denitrification using heterotrophic microorganisms. The C/N ratio is an important factor of the denitrification process. In this case, if methanol is added to increase the lacking organic matter, a high economic cost is incurred and methanol is left in the processed water. In an effort to fix these issues, autotrophic denitrification through the use of Hydrogen, Iron and Sulfur is being studied, and among those Sulfur is cheaper and carries out denitrification effectively, and therefore is being studied the most. In this study, after cultivating T. denitrificans, the presence of T. denitrificans was determined and the effectiveness of denitirification via T. denitrificans was studied. In order to find out about the inhibition of T. denitrificans from the loading of organic matter, this shows that the greater the loading of organic matter, the more the denitrification ability of T. denitrificans is hindered. In order to research the hindrance of T. denitrificans resulting from the loading of $NO_3{^-}-N$, these results show that concentrations less than 100mg/L per 100mL of gel volume do not hinder T. denitrificans. In order to research the optimization of denitrification resulting from T. denitrificans, three 500mL samples of Sulfur granules were prepared: 1) one with only T. denitrificans attached (Mode I), 2) one with both T. denitrificans and active sludge attached (Mode II), and 3) one with only active sludge attached (Mode III). The results showed that autotrophic denitrification using S from Mode I was the most active.

• 한국환경농학회:학술대회논문집
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• 한국환경농학회 2011년도 30주년 정기총회 및 국제심포지엄
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• pp.296-296
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• 2011

• Journal of Microbiology and Biotechnology
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• 제22권8호
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• pp.1155-1160
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• 2012

Sulfur-utilizing autotrophic denitrification relies on an inorganic carbon source to reduce the nitrate by producing sulfuric acid as an end product and can be used for the treatment of wastewaters containing high levels of nitrates. In this study, sulfur-denitrifying bacteria were used in anoxic batch tests with sulfur as the electron donor and nitrate as the electron acceptor. Various medium components were tested under different conditions. Sulfur denitrification can drop the medium pH by producing acid, thus stopping the process half way. To control this mechanism, a 2:1 ratio of sulfur to oyster shell powder was used. Oyster shell powder addition to a sulfur-denitrifying reactor completely removed the nitrate. Using 50, 100, and 200 g of sulfur particles, reaction rate constants of 5.33, 6.29, and $7.96mg^{1/2}/l^{1/2}{\cdot}h$ were obtained, respectively; and using 200 g of sulfur particles showed the highest nitrate removal rates. For different sulfur particle sizes ranging from small (0.85-2.0 mm), medium (2.0-4.0 mm), and large (4.0-4.75 mm), reaction rate constants of 31.56, 10.88, and $6.23mg^{1/2}/l^{1/2}{\cdot}h$ were calculated. The fastest nitrate removal rate was observed for the smallest particle size. Addition of chemical oxygen demand (COD), methanol as the external carbon source, with the autotrophic denitrification in sufficiently alkaline conditions, created a balance between heterotrophic denitrification (which raises the pH) and sulfur-utilizing autotrophic denitrification, which lowers the pH.

• Journal of Microbiology and Biotechnology
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• 제18권11호
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• pp.1826-1835
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• 2008

An autotrophic denitrification reactor (ADR-l) and a heterotrophic denitrification reactor (HDR-2) were operated to remove nitrate and nitrite in an anoxic environment in raw sewage. The $NO_3$-N removal rate of ADR-l was shown to range from 52.8% to 78.7%, which was higher than the $NO_3$-N removal rate of HDR-2. Specific denitrification rates (SDNR) of ADR-l and HDR-2 were 3.0 to 4.0 and 1.1 to $1.2\;mgNO_3$-N/gVSS/h, respectively. From results of restriction fragment length polymorphism (RFLP) of the 16S rRNA gene, Aquaspirillum metamorphum, Alcaligenes defragrans, and Azoarcus sp. were $\beta$-Proteobacteria that are affiliated with denitritying bacteria in the ADR-l. Specifically, Thiobacillus denitrificans was detected as an autotrophic denitrification bacteria. In HDR-2, the $\beta$-Proteobacteria such as Denitritying-Fe-oxidizing bacteria, Alcaligenes defragrans, Acidovorax sp., Azoarcus denitrificans, and Aquaspirillum metamorphum were the main bacteria related to denitrifying bacteria. The $\beta$-and $\alpha$-Proteobacteria were the important bacterial groups in ADR-l, whereas the $\beta$-Proteobacteria were the main bacterial group in HDR-2 based on results of fluorescent in situ hybridization (FISH). The number of Thiobacillus denitrificans increased in ADR-l during the operation period but not in HRD-2. Overall, the data presented here demonstrate that many heterotrophic denitritying bacteria coexisted with autotrophic denitrifying bacteria such as Thiobacillus denitrificans for nitrate removal in ADR-l. On the other hand, only heterotrophic denitritying bacteria were identified as dominant bacterial groups in HDR-2. Our research may provide a foundation for the complete nitrate removal in raw sewage of low-COD concentration under anoxic condition without any external organic carbon or the requirement of post-treatment.

• Environmental Engineering Research
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• 제10권6호
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• pp.283-293
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• 2005

Characteristics of sulfur-based autotrophic denitrification in a semi-continuous type reactor and the kinetic parameters were studied. Enriched autotrophic denitrifying culture was used for the reactor operation. Biomass growth on sulfur particles and in the liquid medium was monitored using the DAPI staining method. From the result of ion concentration changes and the biomass growth, maximum specific growth rate, ${\mu}_{max}$, and the half velocity constant, $K_M$, were estimated as $0.61\;d^{-1}$ and 3.66 mg/L, respectively. Growth yield coefficient, Y values for electron acceptor and donor were found as 0.49 gVSS/g N and 0.16 gVSS/g S. The biomass showed specific denitrification rate, ranging 0.86-1.13 gN/g VSS-d. A half-order equation was found to best simulate the denitrification process in the packed bed reactor operated in the semi-continuous mode.

• Journal of Microbiology and Biotechnology
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• 제25권10호
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• pp.1670-1679
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• 2015

Two hollow fiber membrane biofilm reactors (HF-MBfRs) were operated for autotrophic nitrification and hydrogenotrophic denitrification for over 300 days. Oxygen and hydrogen were supplied through the hollow fiber membrane for nitrification and denitrification, respectively. During the period, the nitrogen was removed with the efficiency of 82-97% for ammonium and 87-97% for nitrate and with the nitrogen removal load of 0.09-0.26 kg NH₄⁺-N/m³/d and 0.10-0.21 kg NO₃^--N/m³/d, depending on hydraulic retention time variation by the two HF-MBfRs for autotrophic nitrification and hydrogenotrophic denitrification, respectively. Biofilms were collected from diverse topological positions in the reactors, each at different nitrogen loading rates, and the microbial communities were analyzed with partial 16S rRNA gene sequences in denaturing gradient gel electrophoresis (DGGE). Detected DGGE band sequences in the reactors were correlated with nitrification or denitrification. The profile of the DGGE bands depended on the NH₄⁺ or NO₃^- loading rate, but it was hard to find a major strain affecting the nitrogen removal efficiency. Nitrospira-related phylum was detected in all biofilm samples from the nitrification reactors. Paracoccus sp. and Aquaspirillum sp., which are an autohydrogenotrophic bacterium and an oligotrophic denitrifier, respectively, were observed in the denitrification reactors. The distribution of microbial communities was relatively stable at different nitrogen loading rates, and DGGE analysis based on 16S rRNA (341f /534r) could successfully detect nitrate-oxidizing and hydrogen-oxidizing bacteria but not ammonium-oxidizing bacteria in the HF-MBfRs.

• 대한환경공학회지
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• 제22권11호
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• pp.1995-2005
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• 2000

황-이용 탈질시 요구되는 알칼리도를 공급하기 위해 종속영양탈질을 동시에 이용하는 방안(종속/독립 동시탈질)의 가능성을 검토하였다. 이를 위해 $35^{\circ}C$에서 운전된 황 충전상 반응조에 $NO_3{^-}-N$ 및 $COD_{Cr}$이 각각 700~900 및 900~2500mg/L인 질산화된 침출수를 주입하며 종속/독립 동시탈질시 첨가된 외부탄소원의 종류 및 농도, 그리고 HRT가 탈질효율에 미치는 영향을 파악하였다. 종속/독립 동시탈질시 알칼리도 공급량을 0으로 유지하기 위해 종속영양탈질에 의해 제거되어야 하는 $NO_3{^-}-N$분율($HDNR_{fraction}$)은 탄소원별로 차이를 나타내었다. 메탄올과 아세트산 나트륨의 경우 이론적인 $HDNR_{fraction}$ 값에서 100%의 탈질효율을 얻었으나 글루코스와 당밀의 경우 이론치보다 높은 $HDNR_{fraction}$ 값이 필요하였다. 대부분의 탈질반응은 반응조 하단 11.5cm에서 완료되었으며, 이를 기준으로 계산한 종속/독립 동시탈질시 100% 탈질효율을 얻을 수 있는 EBCT와 용적부하는 각각 6.76 h와 $2.84kg-NO_3{^-}-N/m^3{\cdot}d$이었고, 최대 탈질율은 처리효율 89%에서 $5.05kg-NO_3{^-}-N/m^3{\cdot}d$이었다. 그러나 짧은 EBCT에서는 종속 영양균의 과도한 성장에 의한 반응조의 막힘현상이 발생하였는 바, 이는 역세척 또는 종속영양탈질과 황-이용 탈질의 분리운전 등의 대안으로 해결할 수 있을 것이다.