• Title/Summary/Keyword: high temperature retention time

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Optimization for SBR Process of Two-Sludge Type (Two-sludge 유형 SBR 공정의 최적 운영 조건 도출)

  • Ryu, Hong-Duck;Hwang, Jae-Sik;Kim, Keum-Yong;Lee, Sang-Ill
    • Journal of Korean Society of Environmental Engineers
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    • v.29 no.2
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    • pp.229-234
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    • 2007
  • In the present work, the sequencing batch reactor process of two-sludge type was optimized. The effects of solid retention time, hydraulic retention time, length of biosorption phase and temperature variation were investigated, respectively. In the T-N removal, the long solid retention time was favored. It was speculated that SCOD biosorption efficiency was higher in long solid retention time than in short solid retention time. In the comparison of hydraulic retention time, the removal efficiency of $NH_4^+-N$ and T-N were almost same in all applied hydraulic retention times which were 8 hr, 10 hr and 15 hr. It was observed that there was no need to have the hydraulic retention time more than 20 min in biosorption phase for enhancement of T-N removal efficiency. An experimental comparison of removal efficiencies with different temperature conditions was carried out. Decrease of temperature didn't affect the performance of the process, however, phosphorus removal efficiency was a little higher at low temperature than high temperature. Consequently, the process developed in this study was much amenable to wastewater treatment which was conducted in the low temperature and high loading rate.

Experimental Study on the Foaming Characteristics according to the Plastic Temperature and the Retention Time of Shale (혈암의 소성온도 및 체류시간에 따른 발포특성에 관한 실험적 연구)

  • Mun, Dong Hwan;Lee, Han Seung
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2018.05a
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    • pp.58-59
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    • 2018
  • In this study, firing experiments were carried out to confirm the foamability of the expansive shale collected from the local area. When expansive shales are subjected to high temperature heat, gas is generated inside and voids are formed. Due to this phenomenon, shale is used as a raw material for lightweight aggregate. Experiments were carried out with different plastic temperature and residence time to find the appropriate plastic temperature for this expansive shale. As a result, the higher the plastic temperature, the more the surface viscosity increased and the gas generated inside were retained. Resulting in a number of internal voids. However, even if the plastic temperature or the medium temperature is high, it is confirmed that sufficient gas is not generated when the residence time is shortened.

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Investigation of influence of temperature and solid retention time on membrane fouling in MBR

  • Mirzavandi, Atoosa;Hazrati, Hossein;Ebrahimi, Sirous
    • Membrane and Water Treatment
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    • v.10 no.2
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    • pp.179-189
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    • 2019
  • This study aimed to investigate the effect of temperature and solid retention time (SRT) on membrane fouling in a membrane bioreactors (MBRs). For this purpose, a lab-scale submerged MBR system was used. This system operated at two SRTs of 15 and 5 days, three various temperatures (20, 25 and $30^{\circ}C$) and hydraulic retention time (HRT) of 8 h. The results indicated that decreased the cake layer resistance and increased particles size of foulant due to increasing temperature and SRT. Fourier transform infrared (FTIR) analysis show that the cake layer formed on the membrane surface, contained high levels of proteins and especially polysaccharides in extracellular polymeric substances (EPS) but absorbance intensity of EPS functional groups decreased with temperature and SRT. EEM analysis showed that the peak on the range of Ex/Em=220-240/350-400 in SRT of 15 and temperature of $30^{\circ}C$ indicates the presence of fulvic acid in the cake. In addition, as the temperature rise from 20 to $30^{\circ}C$, concentration of soluble microbial products (SMP) increased and COD removal reached 89%. Furthermore, the rate of membrane fouling was found to increase with decreasing temperature and SRT.

Comparison of Anaerobic Digestion Efficiency with Different Temperature of Food Wastes (음식물류폐기물의 성상별 온도변화에 따른 혐기성소화 효율 비교 연구)

  • Hwang, Kwanghyun;Kim, Dongik
    • Journal of Korean Society on Water Environment
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    • v.35 no.4
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    • pp.332-339
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    • 2019
  • A comparative study on the anaerobic digestion efficiency according to the temperature change was conducted considering the characteristics of domestic food wastes with high water content of about 80 % or more. The substrate was tested for anaerobic digestion efficiency in two substrates, a liquid component separated naturally from food waste and food waste itself. In the anaerobic digestion experiments, the digestion efficiency was the highest at $55^{\circ}C$ (thermophilic temperature). However, the digestion efficiency at $45^{\circ}C$(middle high temperature) was lower than that at $35^{\circ}C$(mesophilic temperature). The comparison of general food wastes anaerobic digestion requiring 30 days of hydraulic retention time to the liquid component indicated a stable digestion efficiency even after 15 days of hydraulic retention time.In the experiments conducted on food waste, the digestion efficiency at $55^{\circ}C$ was higher than that at $35^{\circ}C$. When the food waste, especially the liquid component originating from food waste, is treated by anaerobic digestion method, the mesophilic temperature and thermophilic temperature conditions are more favorable in the digestion efficiency than the middle high temperature ($45^{\circ}C$). However, when applying thermophilic or mesophilic temperature anaerobic digestion process operation in the field, the amount of energy input should be considered.

Biological Removal Phosphorus Containing Swine Wastewater (생물학적 처리에 의한 돈사폐수의 인제거)

  • 신남철;박정호
    • Journal of Environmental Health Sciences
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    • v.26 no.4
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    • pp.15-20
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    • 2000
  • The studies of swine wastewater treatment aim to development of process using soil microorganism. Removal rate of swine wastewater containing organic matter was 99 percent in case of high loading rate. Microorganism was devoted to improve the treatment efficiency of the process. According to the result obtained from biological treatment of high loading rate swine wastewater. Hydraulic retention time was 2.3 days in unit process of biological phosphorus removal. BO $D_{rm}$ / $P_{rm}$ ratio was 1122 in room temperature anaerobic process and 355.6 in mesophilic anaerobic process. And then phosphorus removal rate mesophilic anaerobic process was 3 time as much as than room temperature acaerobic process.

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Effects of High Temperature Maintenance Time and Curing Method on Compressive Strength of FA Large Volume Replacement Mortar after Application of Resuscitation Material (소생재 도포 후 고온 유지시간 및 양생방법 변화가 Fly Ash 다량치환 모르타르의 압축강도에 미치는 영향)

  • Choi, Yoon-Ho;Lee, Hyuk-Ju;Lee, Young-Jun;Hyun, Seung-Yong;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2019.11a
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    • pp.141-142
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    • 2019
  • In this study, we conducted a comparative analysis of the effects of retention time and resuscitation method on the degree of resuscitation after reapplying mortar with much FA replacement. Results After applying NaOH to the top surface of 60 % FA-substituted mortar, the degree of resuscitation at $40^{\circ}C$ was high enough to increase the overall curing time, but there was no significant difference. However, with regard to the curing method, middle curing showed the greatest manifestation, followed by wrapping and underwater curing, but there was no significant difference. The resuscitation level on the 28th of the lumber was found to be revived to about 70~80 % at around 30 % without resuscitation.

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Assessment of Degradation Rate Coefficient and Temperature Correction Factor by Seasonal Variation of Concentration and Temperature in Livestock Wastewater Treatment in Field Scale (현장수준의 축산폐수처리에 있어서 계절별 농도 및 온도변화에 따른 분해반응계수 및 온도보정계수의 산정)

  • 박석환
    • Journal of Environmental Health Sciences
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    • v.22 no.2
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    • pp.90-95
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    • 1996
  • This study was performed to calculate the degration rate coefficient, operating parameters to meet the effluent standards, and the temperature adjustment coefficients to each parameter of pollution by seasonal variation of concentration and temperature of influent in livestock wastewater treatment by sequencing batch reactor process in field scale. The followings are the conclusions that were derived from this study. 1. In the field, temperature of livestock wastewater in reactor was 20.3$\circ$C in summer and 6.0$\circ$C in winter. The ratio of BOD:TKN: T-P in influent was 100:80:7. BOD loadings in winter and spring were 0.26 and 0.43 kg $BOD/m^3$ day, respectively. Those in summer and fall were 0.25 and 0.13 kg $BOD/m^3$ day, respectively. 2. The degradation rate coefficient for TKN was larger in summer and fall in which temperature was high than that in which temperature was high than that in winter and spring in which concentration was high. On the contrary, the phosphorus uptake rate was larger in winter and spring than that in summer and fall. 3. The hydraulic retention time in winter and spring was longer than that in summer and fall. Especially, in order to meet the standard for TKN of 120 mg/l in winter in which temperature of wastewater was 6.0$\circ$C, as the MLSS concentration was increased from 4, 000 to 7, 000 mg/l, the hydraulic retention time was increased from 212 to 121 hours. But, in order to shorten that less than 121 hours for the economical wastewater treatment, countermeasure to increase temperature of wastewater in the reactor should be considered. 4. the temperature adjustment coefficients for BOD, $COD_{Mn}$, TKN and T-P were 1.0241, 1.0225, 1.0541 and 1.0495, respectively. Namely, the treatment of TKN was most sensitively affected by temperature. For the purpose of the effective removal of nitrogen and phosphorus which are sensitive to temperature, it is necessary to keep the temperature of livestock wastewater more than 20$\circ$C which is the temperature of it in summer.

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A Study on the Fatigue and Data Retention Characteristics of Single Grained PZT Thin Films (단결정립 PZT 박막의 피로 및 정보 유지 특성에 관한 연구)

  • Lee, Jang-Sik;Ju, Seung-Gi
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.37 no.5
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    • pp.1-8
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    • 2000
  • Fatigue and data retention characteristics of the Pt/PZT/Pt structure using single grain PZT thin films by PZT seeding method were investigated. In case of fatigue, there is no loss in switched polarization up to 2$\times$10$^{11}$ cycles using 1MHz square wave form at $\pm$10V and no data loss after 30000sec of memory retention at room temperature. From the activation energy measured at high temperatures, the time required 20% loss in remanent polarization is estimated to be 6.6$\times$10$^{7}$ years at room temperature.

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Study on Image Retention in an AC Plasma Display Panel

  • Kim, Sang-Ho;Choi, Kyung-Cheol;Shin, Bhum-Jae
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07a
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    • pp.259-262
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    • 2005
  • Image retention is a kind of fatal shortcoming of the AC PDPs for realizing high-quality picture. In this work, the measurement method of image retention was proposed using temporal measurement of luminance, CIEXYZ tristimulus values, IR emission of reset pulse, and temperaturel. On the base of temporal measurement of luminance, CIEXYZ tristimulus value, and IR emission of reset pulse, the retention time of Ne+5%Xe gas-mixture discharge was about 2 hours after white window image. However, it was about 20 minute on the base of temporal measurement of temperature.

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A Study on Characteristic of NO Reduction by High Level O2Gas in Selective Non-Catalystic Reaction (High Level O2배가스중 NO 저감에 대한 선택적비촉매환원 반응특성에 관한 연구)

  • 이강우;정종현;오광중
    • Journal of Environmental Science International
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    • v.11 no.6
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    • pp.577-582
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    • 2002
  • Selective catalytic reduction and selective non-catalytic reduction processes are mainly used to treat nitrogen oxidants generated from fossil-fuel combustion. Especially, the selective non-catalytic reduction process can be operated more economical and designed more simply than the selective catalytic reduction. For this reason, many researchers carried out to increase the removal efficiency of nitrogen oxidants in the condition of low oxygen concentration by using the selective non-catalytic reduction process. However, this study was flue gas contained high oxygen concentration of 20(v/v%) with ammonia as a reducing agent. Moreover, it carried out experiment with many factors that are reaction temperature, retention time, initial NO concentration, NSR(normalized stoichiometric ratio). It was determined optimal operating conditions to improve NO removal efficiency with SNCR process. The De-NOx efficiency was increased with NSR, initial NO concentration and retention time increasement. This study has NO removal efficiency over 80% in the high oxygen concentration as well as low oxygen concentration. The injection of reducing agent may be considered for SNCR process and facility operation in 850$\^{C}$ of optimal condition.