• Title/Summary/Keyword: volumetric loading rate

Search Result 68, Processing Time 0.028 seconds

A Use of Heterotrophic Denitrification for the Supply of Alkalinity during Sulfur-utilizing Autotrophic Denitrification (황-이용 독립영양 탈질시 알칼리도 저감을 위한 종속영양 탈질의 이용방안)

  • Lee, Dong-Uk;Park, Jae-Hong;Bae, Jae-Ho
    • Journal of Korean Society of Environmental Engineers
    • /
    • v.22 no.11
    • /
    • pp.1995-2005
    • /
    • 2000
  • The use of heterotrophic denitrification as an alternative method for supplying alkalinity during sulfur-utilizing autotrophic denitrification was evaluated by examining the effects of external carbon source (both type and concentration) and HRT on denitrification efficiency. Concentrations of $NO_3{^-}-N$ and $COD_{Cr}$ of nitrified landfill leachate used for experiment were 700-900mg/L and 900-2500mg/L. respectively, All experiment was conducted with sulfur packed bed reactors (SPBRs) which were operated at $35^{\circ}C$. The fraction of $NO_3{^-}-N$ removed by heterotrophic denitrification ($HDNR_{fraction}$) to balance the alkalinity consumption by autotrophic denitrification varied with the type of external carbon source. When methanol and sodium acetate was added at theoretical HDNRfraction value. 100% denitrification was achieved without alkalinity addition. However, glucose and molasses require $HDNR_{fraction}$ value greater than theoretical value for complete denitrification. The EBCT and volumetric loading rate at which 100% denitrification efficiency could be achieved were 6.76 h and $2.84kg-NO_3{^-}-N/m^3{\cdot}d$, respectively, based on the fact that 100% denitrification occurred within the bottom 11.5 cm layer of the SPBR. The maximum nitrogen removal rate occurred with 89% removal efficiency at loading rate of $5.05kg-NO_3{^-}-N/m^3{\cdot}d$. However, at short EBCT, clogging of SPBR was observed with excess growth of heterotrophic denitrifiers. This problem may be eliminated by back washing or by separating of heterotrophic denitrification from sulfur-utilizing denitrification.

  • PDF

Nitrogen Removal using Autotrophic Microorganism in Membrane-Attached Biofilm Reactor (MABR) (Membrane-Attached Biofilm Reactor(MABR)에서의 독립영양 미생물을 이용한 질소 제거)

  • Shin, Jeong-Hoon;Sang, Byoung-In;Chung, Yun-Chul;Choung, Youn-Kyoo
    • Journal of Korean Society on Water Environment
    • /
    • v.21 no.6
    • /
    • pp.624-629
    • /
    • 2005
  • The purpose of this study is to investigate the performance of nitrogen removal using autotrophic microorganism in the Membrane-Attached Biofilm Reactor (MABR). The treatment system consists of an aerobic MABR (R1) for nitrification and an anaerobic MABR (R2) for hydrogenotrophic denitrification. Oxygen and hydrogen were supplied through the lumen of hollow-fiber membranes as electron acceptor and donor, respectively. In phase Ι, simultaneous organic carbon removal and nitrification were carried out successfully in R1. In phase II, to develop the biofilm on the hollow-fiber membrane surface and to acclimate the microbial community to autotrophic condition, R1 and R2 were operated independently. The MABRs, R1 and R2 were connected in series continuously in phase III and operated at HRT of 8 hr or 4 hr with $NH_4{^+}-N$ concentration of influent, from 150 to 200 mgN/L. The total nitrogen removal efficiency reached the maximum value of 99% at the volumetric nitrogen loading rate of $1.20kgN/m^3{\cdot}d$ in the combined MABR system with R1 and R2. The results in this study demonstrated that the combined MABR system could operate effectively for the removal of nitrogen in wastewater not containing organic materials and can be used stably as a high rate nitrogen removal technology.

Effect of Sulfate and Heavy Metals on Methanogenic Activation of in the Anaerobic Digestion of Tannery Wastes (피혁폐수의 혐기성 소화시 황산염과 중금속이 메탄균 활성에 미치는 영향)

  • Shin, Hang Sik;Oh, Sae Eun
    • Journal of the Korea Organic Resources Recycling Association
    • /
    • v.4 no.1
    • /
    • pp.13-21
    • /
    • 1996
  • For treating tannery wastewater containing high sulfate and heavy metals, test was performed to assess their performance, competition between SRB (sulfate reducing bacteria) and MPB (methane producing bacteria), and the activity of MPB according to change of chromium concentrations. COD removal efficiency was above 70% at VLR (volumetric loading rate) of 2.0 gCOD/I.day and HRT (hydraulic retention time) of 18hrs at $35^{\circ}C$. In the competition between SRB and MPB, about 15% of the removed COD was utilized by SRB in the begining, but it became 43% at the end. It indicated that MPB was strongly suppressed by the occurrence of significant sulfate reduction since a large electron flow was uptaken by SRB. For the entire experiment, removal efficiencies of chromium concentration were more than 90%. Despite high removal efficiencies of chromium concentration, performance of reactor did not change significantly during the experimental periods. Expecially, chromium (III) is tannery wastewater is less toxic than chromium (VI).

  • PDF

Effects of Alkalinity on the Nitrification Capability of Nonwoven Fabric Filter Bioreactor (부직포 여과막 생물반응조에서 알칼리도가 질산화 성능에 미치는 영향)

  • Bae, Min-Su;Ahn, Yoon-Chan;Jang, Myung-Bae;Cho, Yun-Kyung;Cho, Kwang-Myeung
    • Journal of Korean Society of Environmental Engineers
    • /
    • v.29 no.7
    • /
    • pp.783-792
    • /
    • 2007
  • To investigate the effects of alkalinity on the nitrification capability of the nonwoven fabric filter bioreactor(NFBR), an experiment was performed for 641 days at a hydraulic retention time of approximately 11 hours by changing the influent concentration of $NH_3-N$ from 54 mg/L to 1,400 mg/L and alkalinity from 43 mg/L to 10,480 mg/L. The MLSS concentration reduced from an initial value of 2,650 mg/L down to 830 mg/L, then increased up to 8,340 mg/L. Though the volumetric loading rate varied in a range of $0.120\sim3.130$ kg $NH_3-N/m^3-day$, the F/M ratio showed a narrow range of $0.067\sim0.414$ kg $NH_3-N/kg$ MLSS-day. The average nitrification efficiency at each experimental stage resulted in the range of $35.2\sim100%$, and the maximum nitrification rate was 2.970 kg $N/m^3-day$ or 0.489 g N/g MLVSS-day. The nitrifiers' fraction of the MLVSS increased up to 100% from an initial value of 7.1% and the biofilm formed on the nonwoven fabric filter showed a very low nitrifiers' fraction of mere 2.2%. The growth yield of the MLSS and the alkalinity consumption rate were computed to be 0.117 g VSS/g N removed and 7.08 g alkalinity/g $NO_x^--N$ produced, respectively. Results of the research suggest that NFBR could be an adequate process for nitrification of wastewaters with high ammonia concentrations.

Continuous Mesophilic-Dry Anaerobic Digestion of Organic Solid Waste (유기성고형폐기물의 연속 중온 건식혐기성소화)

  • Oh, Sae-Eun;Lee, Mo-Kwon;Kim, Dong-Hoon
    • Journal of Korean Society of Environmental Engineers
    • /
    • v.31 no.5
    • /
    • pp.341-345
    • /
    • 2009
  • Continuous dry anaerobic digestion of organic solid wastes (30% TS, Total Solids) comprised of food waste and paper was performed under mesophilic condition. During the operation, hydraulic retention time (HRT) was decreased as follows: 150 d, 100 d, 60 d, and 40 d, which corresponded to the solid loading rate of 2.0, 3.0, 5.0, and 7.5 kg TS/$m^3$/d, respectively. Volumetric biogas production rate ($m^3$/$m^3$/d) increased as HRT decreased, and the highest biogas production rate of 3.49${\pm}$0.31 $m^3$/$m^3$/d was achieved at 40 d of HRT. At this HRT, high volatile solids (VS) reduction of 76% was maintained, and methane production yield of 0.25 $m^3$/kg $TS_{added}$ was achieved, indicating 67.4% conversion of organic solid waste to bioenergy. The highest biogas production yield of 0.52 $m^3$/kg $TS_{added}$ was achieved at 100 d of HRT, but it did not change much with respect to HRT. For the ease feed pumping, some amount of digester sludge was recycled and mixed with fresh feed to decrease the solid content. Recirculation volume of 5Q was found to be the optimal in this experimental condition. Specific methanogenic activity (SMA) of microorganisms at mesophilic-dry condition was 2.66, 1.94, and 1.20 mL $CH_4$/g VS/d using acetate, butyrate, and propionate as a substrate, respectively.

Evaluation of various nutrients removal models by using the data collected from stormwater wetlands and considerations for improving the nitrogen removal (인공습지에서 영양소 제거 설계모델 검토 및 질소제거 개선방안에 대한 고찰)

  • Park, Kisoo;Kim, Youngchul
    • Journal of Wetlands Research
    • /
    • v.19 no.1
    • /
    • pp.90-102
    • /
    • 2017
  • In this study, various types of nutrient models were tested by using two tears's water quality data collected from the stormwater wetland in Korea. Based on results, most important factor influencing nitrogen removal was hydraulic loading rate, which indicates that surface area of wetland is more important than its volumetric capacity, and model proposed by WEF was found to give a least error between measured and calculated values. For the phosphorus, in case assuming a power relationship between rate constant and temperature, the best prediction result were obtained, but temperature was most sensitive parameter affecting phosphorus removal. In addition, denitrification was always a limiting step for the nitrogen removal in this particular wetland mostly due to the lack of carbon source and high dissolved oxygen concentration. In this paper, several alternatives to improve nitrogen removal, including proper arrangement and designation of wetland elements and use of floating plants or synthetic fiber mat to control oxygen level and to capture the algal particles were proposed and discussed.

Kinetic of Catalytic CO2 Gasification for Cyprus Coal by Gas-Solid Reaction Model (기-고체 반응모델을 이용한 Cyprus탄의 CO2 저온촉매가스화 반응거동)

  • Hwang, Soon Choel;Lee, Do Kyun;Kim, Sang Kyum;Lee, Si Hyun;Rhee, Young Woo
    • Korean Chemical Engineering Research
    • /
    • v.53 no.5
    • /
    • pp.653-662
    • /
    • 2015
  • In general, the coal gasification has to be operated under high temperature ($1300{\sim}1400^{\circ}C$) and pressure (30~40 bar). However, to keep this conditions, it needs unnecessary and excessive energy. In this work, to reduce the temperature of process, alkali catalysts such as $K_2CO_3$ and $Na_2CO_3$ were added into Cyprus coal. We investigated the kinetic of Cyprus char-$CO_2$ gasification. To determine the gasification conditions, the coal (with and without catalysts) gasified with fixed variables (catalyst loading, catalytic effects of $Na_2CO_3$ and $K_2CO_3$, temperatures) by using TGA. When catalysts are added by physical mixing method into Cyprus coal the reaction rate of coal added 7 wt% $Na_2CO_3$ is faster than raw coal for Cyprus char-$CO_2$ gasification. The activation energy of coal added 7 wt% $Na_2CO_3$ was calculated as 63 kJ/mol which was lower than raw char. It indicates that $Na_2CO_3$ can improve the reactivity of char-$CO_2$ gasification.

Enhanced Anaerobic Degradation of Food Waste by Employing Rumen Microorganisms (Rumen 미생물을 이용한 주방폐기물 혐기성소화의 효율증진 방안)

  • Shin, Hang-Sik;Song, Young-Chae;Son, Sung-Sub;Bae, Byung-Uk
    • Journal of the Korea Organic Resources Recycling Association
    • /
    • v.1 no.1
    • /
    • pp.103-113
    • /
    • 1993
  • Every year, over $3.37{\times}10^7$ ton of municipal solid waste is generated in Korea, of which about 28% is organic food waste from restaurant, dining halls and households etc. Methane conversion of the food waste by anaerobic digestion could be a viable approach for energy recovery as well as safe disposal of the waste. However, as food waste is composed of highmolecular complex polymers such as cellulose, lignin and protein, anaerobic digestion of food waste has not been efficient in terms of volumetric loading rate, solid retention time and extent of anaerobic degradation. In this research, the improved anaerobic degradation of food waste was attemped by applying rumen microorganisms to anaerobic digestion. Acidification efficiency of food waste by rumen microorganisms was compared with that of conventional acidogenesis. And optimum acidification conditions by rumen microorganisms were also determined. For the experiments, anaerobic batch reactors of 600 mL was fed with the processed (dried and milled) food waste obtained from a restaurant. Ultimate volatile fatty acid (VFA) yield produced by rumen microorganisms was about 8.4 meq VFA/g volatile solid (VS) that is 95% of the theoretical value. This yield was not much different from that of conventional acidogenesis, but hydrolysis rate was about twice faster. Cumulative VFA concentration increased from 66 meq/L to 480 meq/L, when the initial TS was increased from 1% to 15%. But VFA yield at 15% TS was half of that at 1% TS. This inhibition on the acidification might be caused by the rapid drop of pH and higher concentration of nonionized VFA. Optimal pH and temperature range for the acidification were about 6.0~7.5 and $35{\sim}45^{\circ}C$, respectively.

  • PDF