• Title/Summary/Keyword: Continuously stirred tank reactor

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Acidogenesis of Lipids-Containing Wastewater in Anaerobic Sequencing Batch Reactor (혐기성 연속 회분식 반응조를 이용한 지질 함유 폐수의 산발효 특성)

  • Kim, Sang-Hyoun;Shin, Hang-Sik
    • Journal of Korean Society of Environmental Engineers
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    • v.31 no.12
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    • pp.1075-1080
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    • 2009
  • The partial lipid degradation with the saturation of double-bond at the acidogenesis stage is known to help subsequent methanogenesis during anaerobic digestion. Acidogenic reactions in an anaerobic sequencing batch reactor (ASBR) and a continuously stirred tank reactor (CSTR) were carried out to compare their performances. A mixture of two unsaturated (oleate and linoleate) and two saturated (palmitate and stearate) long-chain fatty acids (LCFAs) was used as a model substrate. Biomass retention in the ASBR contributed to the enhanced performance at hydraulic retention time (HRT) below 15 hr. Biomass retention in the ASBR contributed to the enhanced performance compared to CSTR even at shorter HRT. ASBR would be a proper reactor configuration for the acidogenesis of lipid-containing wastewater.

A Study on the Substrate Removal Efficiency with Varing SRT in Anaerobic Treatment of High Organic Wastewater (고농도 유기성폐수의 혐기성처리시 SRT변화에 따른 유기물질 제거효율에 관한 연구)

  • Kim Byeong Ho;Kim Dong Min
    • Journal of environmental and Sanitary engineering
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    • v.4 no.1 s.6
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    • pp.43-52
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    • 1989
  • A synthetic wastewater composed of powdered baby food and inorganic nutrients was treated by five 3.6L anaerobic reactors in order to test the relationship between solids retention time (SRT) and media surface ratio, and the removal efficiencies of organic substrate. Of the five reactors, four were semi-continuously fed stirred-tank reactors and one continuously-stirred batch reactor. The influent was 7430mg/L in COD, 7120 mg/L $BOD_L$ and 6350mg/L in $BOD_5$, respectively. Operating temperature was $35{\pm}1^{\circ}C$ and pH in the range 6.9 to 7.2. In this experimental study it was found that a linear relationship existed, within the experiment range, between SRT and media surface ratio, and that SRT and removal efficiency increased with increasing media surface ratio. The substrate removal efficiencies were 82.7 to $88.2\%$ in COD, 82.9 to $88.4\%$ in $BOD_L$ and 83.3 to $88.7\%$ in $BOD_5$, respectively.

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Monitoring Anaerobic Reductive Dechlorination of TCE by Biofilm-Type Culture in Continuous-Flow System (연속흐름반응조에서 바이오필름형태의 탈염소화 미생물에 의한 TCE분해 모니터링)

  • Park, Sunhwa;Han, Kyungjin;Hong, Uijeon;Ahn, Hongil;Kim, Namhee;Kim, Hyunkoo;Kim, Taeseung;Kim, Young
    • Journal of Soil and Groundwater Environment
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    • v.17 no.5
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    • pp.49-55
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    • 2012
  • A 1.28 L-batch reactor and continuous-flow stirred tank reactor (CFSTR) fed with formate and trichloroethene (TCE) were operated for 120 days and 56 days, respectively, to study the effect of formate as electron donor on anaerobic reductive dechlorination (ARD) of TCE to cis-1,2-dichloroethylene (c-DCE), vinyl chloride (VC), and ethylene (ETH). In batch reactor, injected 60 ${\mu}mol$ TCE was completely degraded in the presence of 20% hydrogen gas ($H_2$) in less than 8 days by anaerobic dechlorination mixed-culture (300 mg-soluble protein), Evanite Culture with ability to completely degrade tetrachloroethene (PCE) and -TCE to ETH under anaerobic conditions. Once the formate was used as electron donor instead of hydrogen gas in batch or chemostat system, the TCE-dechlorination rate decreased and acetate production rate increased. It indicates that the concentration of hydrogen produced in both systems is possibly more close to threshold for homoacetogenesis process. Soluble protein concentration of Evanite culture during the batch test increased from 300 mg to 688 mg for 120 days. Through the protein monitoring, we confirmed an increase of microbial population during the reactor operation. In CFSTR test, TCE was fed continuously at 9.9 ppm (75.38 ${\mu}mol/L$) and the influent formate feed concentration increased stepwise from 1.3 mmol/L to 14.3 mmol/L. Injected TCE was accumulated at 18 days of HRT, but TCE was completely degraded at 36 days of HRT without accumulation of the injected-TCE during the left of experiment period, getting $H_2$ from fermentative hydrogen production of injected formate. Although c-DCE was also accumulated for 23 days after beginning of CFSTR operation, it reached steady-state in the presence of excessive formate. We also evaluated microbial dynamic of the culture at different chemical state in the reactor by DGGE (denaturing gradient gel electrophoresis).

The Effect of Chlorinated Ethenes and Electron Donor on VC Dehalogenation Rate (염화에텐류 화합물 및 전자공여체가 VC 탈염소화 속도에 미치는 영향)

  • Bae, Jae-Ho;Lee, Il-Su;Park, Young-Koo;Semprini, Lewis
    • Journal of the Korean Applied Science and Technology
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    • v.24 no.4
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    • pp.436-443
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    • 2007
  • Anaerobic reductive dehalogenation of perchloroethene (PCE) was studied with lactate as the electron donor in a continuously stirred tank reactor (CSTR) inoculated with a mixed culture previously shown to dehalogenate vinyl chloride (VC). cis-1,2- dichloroethene (cDCE) was the dominant intermediate at relatively long cell retention times (>56 days) and the electron acceptor to electron donor molar ratio (PCE:lactate) of 1:2. cDCE was transformed to VC completely at the PCE to lactate molar ratio of 1:4, and the final products of PCE dehalogenation were VC (80%) and ethene (20%). VC dehalogenation was inhibited by cDCE dehalogenation. Propionate produced from the fermentation of lactate might be used as electron donor for the dehalogenation. Batch experiments were performed to evaluate the effects of increased hydrogen, VC, and trichloroethene (TCE) on VC dehalogenation which is the rate-limiting step in PCE dehalogenation The addition of TCE increased the VC dehalogenaiton rate more than an increase in the $H_2$ concentration, which suggests that the introduction of TCE induces the production of an enzyme that can comtabolize VC.

Knowledge-Based Unmanned Automation and Control Systems for the Wastewater Treatment Processes (하.폐수 처리장의 원격 모니터링 및 지식 기반 무인 자동화 시스템)

  • Bae, Hyeon;Jung, Jae-Ryong;Seo, Hyun-Yong;Kim, Sung-Shin;Kim, Chang-Won
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 2001.12a
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    • pp.56-59
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    • 2001
  • In this paper, unmaned fully automation systems are applied for the CSTR(Continuously Stirred Tank Reactor) and, SBR (Sequencing Batch Reactor) wastewater treatment pilot plant. This plant is constructed in the country side which is little far from a main city. So networks and wireless modules are employed for the data transmission. The SBR plant has a local control and monitoring system which is contained communication parts which consist of one ADSL (Asymmetric Digital Subscriber Line) network and one CDMA (Code Division Multiple Access) module. Remote control and monitoring systems are constructed at a laboratory in a metropolis.

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Knowledge-Based Unmanned Automation and Control Systems for the Wastewater Treatment Processes (하.폐수 처리장의 원격 모니터링 및 지식 기반 무인 자동화 시스템)

  • Bae, Hyeon;Jung, Jae-Ryong;Seo, Hyun-Yong;Kim, Sung-Shin;Kim, Chang-Won
    • Journal of the Korean Institute of Intelligent Systems
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    • v.11 no.9
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    • pp.844-848
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    • 2001
  • This paper introduces unmaned fully automation systems, which are applied for the CSTR(Continuously Stirred Tank Reactor) and SBR (Sequencing Batch Reactor) wastewater treatment system. The pilot plant is constructed in the country side which is little far from a main city. So networks and wireless modules are employed for the data transmission. The SBR plant has a local control and the remote monitoring system which is contained communication parts which consist of ADSL (Asymmetric Digital Subscriber Line) network and CDMA (Code Division Multiple Access) Wireless module. Remote control and monitoring systems are constructed at laboratory in a metropolis.

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GA-Based Design of a Nonlinear PID Controller and Application to a CSTR Process (GA 기반의 비선형 PID 제어기 설계 및 CSTR 프로세스에 응용)

  • Lee, Joo-Yeon;So, Gun-Baek;Lee, Yun-Hyung;So, Myung-Ok;Jin, Gang-Gyoo
    • Journal of Advanced Marine Engineering and Technology
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    • v.39 no.6
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    • pp.633-641
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    • 2015
  • Several complex processes that are employed in industries, such as shipping, power plants, and the petrochemical industry, involve time-varying behavior as well as strong nonlinear behavior during operation. The fixed-parameter proportional-integral-derivative (PID) controllers have difficulty in dealing with control problems that occur in such processes. In this paper, we propose a method of designing a nonlinear PID controller for industrial processes that exhibit a large number of nonlinearities and time-varying behavior. The gains of the nonlinear PID controller are characterized by a simple nonlinear function of the error and/or error rate depending on the process set-point and output. We tune the user-defined parameters using a genetic algorithm by minimizing the integral of time absolute error (ITAE) index. We verify the effectiveness of the proposed method by performing a comparison of the proposed method and two other nonlinear and adaptive methods that are employed for reference tracking, disturbance-rejection performances, and robustness to parameter changes on a continuously stirred tank reactor.

Influence of Operating Parameters on Nitrite Accumulation in a Biofilm Reactor and Supplement of External Carbon Source for Denitrification by Sewage Sludge Solubilization (생물막 반응조에서 아질산염 축적에 미치는 운전인자 영향과 하수슬러지 가용화에 의한 탈질반응의 외부탄소원 공급에 관한 연구)

  • Ahn, Hye Min;Lee, Dae Sung
    • Journal of Korean Society of Environmental Engineers
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    • v.35 no.1
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    • pp.57-63
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    • 2013
  • A combined process consisted of a biofilm reactor and a continuously stirred-tank reactor (CSTR) was investigated for highly loaded ammonium wastewater treatment via nitrite accumulation. To enhance ammonium oxidizing bacteria over nitrite oxidizing bacteria on the surface of carriers, the biofilm reactor was operated at temperature of $35^{\circ}C$ for more than three months but the influent ammonium (500 mg-N/L) was partially oxidized to nitrite (240 mg-N/L). As pH was increased from 7.5 to 8.0, nitrite accumulation was fully achieved due to the inhibition of nitrite oxidizing bacteria under high free ammonia concentration. The biofilm reactor performance was severely deteriorated at the hydraulic retention time of 12 hr, at which incomplete nitrification of ammonia was observed. Various solubilization methods were applied to sewage sludge for enhancing its biodegradability and the combined method, alkaline followed by ultrasonic, gave the highest solubilization efficiency (58%); the solubilized solution was used as the external carbon source for denitrification reaction in CSTR. FISH analysis showed that the dominant microorganisms on the carriers were ammonium oxidizing bacteria such as Nitrosomonas spp. and Nitrospirar spp. but low amounts of nitrite oxidizing bacteria as Nitrobacter spp. was also detected.

Continuous Hydrogen Production by Heterotrophic Growth of Citrobacter amalonaticus Y19 in Trickle Bed Reactor (Citrobacter amalonaticus Y19의 영양종속 성장을 이용한 Trickle Bed Reactor에서의 연속적인 수소생산)

  • Park, Ji-Young;Lee, Tae-Ho;Oh, You-Kwan;Kim, Jun-Rae;Seol, Eun-Hee;Jung, Gyoo-Yeol;Kim, Mi-Sun;Park, Sung-Hoon
    • KSBB Journal
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    • v.20 no.6
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    • pp.458-463
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    • 2005
  • [ $H_2$ ] from CO and water was continuously produced in a trickle bed reactor(TBR) using Citrobacter amalonaticus Y19. When the strain C. was cultivated in a stirred-tank reactor under a chemoheterotrophic and aerobic condition, the high final cell concentration of 13 g/L was obtained at 10 hr. When the culture was switched to an anaerobic condition with the continuous supply of gaseous CO, CO-dependent hydrogenase was fully induced and its hydrogen production activity approached 16 mmol/g cell/hr in 60 hr. The fully induced C. amalonaticus Y19 cells were circulated through a TBR packed with polyurethane foam, and the TBR was operated for more than 20 days for $H_2$ production. As gas retention time decreased or inlet CO partial pressure increased, $H_2$ production rate increased but the conversion from CO to $H_2$ decreased. The maximum $H_2$ production rate obtained was 16 mmol/L/hr at the gas retention time of 25 min and the CO inlet partial pressure of 0.4 atm. The high $H_2$ production rate was attributed to the high cell density in the liquid phase circulating the TBR as well as the high surface area of polyurethane foam used as packing material of the TBR.

Characteristics of Ni1/3Co1/3Mn1/3(OH)2 Powders Prepared by Co-Precipitation in Air and Nitrogen Atmospheres (공기와 질소 분위기에서 공침법으로 합성된 Ni1/3Co1/3Mn1/3(OH)2 분말의 특성 비교)

  • Choi, Woonghee;Park, Se-Ryen;Kang, Chan Hyoung
    • Journal of Powder Materials
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    • v.23 no.2
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    • pp.136-142
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    • 2016
  • As precursors of cathode materials for lithium ion batteries, $Ni_{1/3}Co_{1/3}Mn_{1/3}(OH)_2$ powders are prepared in a continuously stirred tank reactor via a co-precipitation reaction between aqueous metal sulfates and NaOH in the presence of $NH_4OH$ in air or nitrogen ambient. Calcination of the precursors with $Li_2CO_3$ for 8 h at $1,000^{\circ}C$ in air produces dense spherical cathode materials. The precursors and final powders are characterized by X-ray diffraction (XRD), scanning electron microscopy, particle size analysis, tap density measurement, and thermal gravimetric analysis. The precursor powders obtained in air or nitrogen ambient show XRD patterns identified as $Ni_{1/3}Co_{1/3}Mn_{1/3}(OH)_2$. Regardless of the atmosphere, the final powders exhibit the XRD patterns of $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ (NCM). The precursor powders obtained in air have larger particle size and lower tap density than those obtained in nitrogen ambient. NCM powders show similar tendencies in terms of particle size and tap density. Electrochemical characterization is performed after fabricating a coin cell using NCM as the cathode and Li metal as the anode. The NCM powders from the precursors obtained in air and those from the precursors obtained in nitrogen have similar initial charge/discharge capacities and cycle life. In conclusion, the powders co-precipitated in air can be utilized as precursor materials, replacing those synthesized in the presence of nitrogen injection, which is the usual industrial practice.