• Journal of Environmental Science International
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• v.2 no.4
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• pp.299-310
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• 1993

This study was aimed to evaluate the effects of effluent recycling on the UASB reactor performances at the various organic loading rates and influent substrate concentrations. The organic removal efficiency of the reactors operated with effluent recycle were above 85%. However, the efficiencies of the reactors operated without the recycle were below 40% even though the effort to increase the efficiencies was made by changing the influent substrate concentrations and the organic loading rates, and introducing the effluent recycle at the final stage of the experiment. It was realized that the certain amount of effluent recycling from the start-up stage in UASB reactors seemed to be necessary to provide the effective contact chances between the substrate and granular sludge for better performances of the UASB process.

• Journal of Environmental Science International
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• v.2 no.4
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• pp.317-324
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• 1993

Effluent recycling effect on UASB reactor performances is known as an important operational factor. In the present study, the possibility of intermittent recycle in UASB process for saving the power consumption was examined at different organic loading and various operational modes in recycle time period. The organic removal efficiencies of the reactors operated with the intermittent effluent recycle were considerably higher compared to those without the effluent recycle. In the intermittent recycle mode, the organic removal efficiencies slightly decreased as the non-recycle time period in the operational mode increased. Proper ratio of recycle and non-recycle time period in the mode seemed to be required to prevent the produced biogas from accumulation in the sludge bed, which caused dead zone in the reactor and sludge loss when the gas was escaped from the bed at the certain pressure.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.4
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• pp.185-192
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• 1990

A two-phase UASB system was operated for high-rate treatment of concentrated distillery wastewater. The phase separation was obtained by adjusting pH in each reactor. When influent SS concentration was 4.1/g/l, the first phase UASB reactor was effectively operated up to the loading rate of 16.5kg $COD/m^3.day$, producing 3.9g HAc/l.day. In the methanogenic UASB reactor, loading rate up to 44kg $COD/m^3.day$ could be applied while removing 80% of influent COD with a specific gas production of 16.5 l/l. day. After the formation granular sludge in both reactors, it was possible to maintain the appropriate pH in the first phase only by recirculating the effluent from methanogenic phase without the addition of alkaline chemicals.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.203-208
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• 2011

Dumping of wastes at sea will be strongly prohibited from 2012 by London Dumping Convention. So, finding the method for treatment of food waste at ground is needed urgently. The solution for above mentioned problem is the resource development from food waste leachate by using Upflow Anaerobic Sludge Blanket (UASB) process. In this research, we try to find out the effect of effluent recirculation and internal return influence on organic removal efficiency and biogas production. Laboratory investigation was conducted for 25 days with only internal recycling, and then, effluent recirculation was performed. As the result of experiments, the organic removal efficiency was above 90%, and the content of methane was 78~80% during operating time. Also, when UASB reactor was operated to over the 3 Q effluent recirculation, there was not 1 N-NaOH consumption any more, therethrough the experiment was economically and stably carried out.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.28-34
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• 2012

In this study, we operated a UASB (upflow anaerobic sludge blanket) reactor by using foodwaste leachate as a raw material with the method of Mesophilic Digestion ($35{\pm}0.5^{\circ}C$) and Thermophilic Digestion ($55{\pm}0.5^{\circ}C$). During 20 days of operating time with the Mesophilic Digestion, the recirculation ratio of effluent was stepwisely changed in every five days. Thermophilic Digestion was carried out at the same condition for Mesophilic Digestion. Results showed that the organic removal efficiency of Mesophilic Digestion was over 90% and the yield of methane production was from 66 up to 70%. The organic removal efficiency of Thermophilic Digestion was over 80% and the yield of methane production was between 62 to 68%. Also, when UASB reactor was operating to over the 3Q effluent recirculation, the experiment could be carried out economically and stably.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.4
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• pp.497-502
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• 2012

Anaerobic Digestion Process is evaluated as efficient wastewater treatment process with the removal of high concentrations of organic waste and production of biogas. This study was performed using hybrid anaerobic hybrid reactor (AHR) which consists of anaerobic sludge blanket (UASB) and biofilm-coated filter media was applied for Palm Oil Mill Effluent (POME) for 80 days to know optimum removal efficiency and production of biogas by comparing each part which divided changing Organic Loading Rate (OLR). As a result of this study, the removal efficiency was 90.4 % when the organic loading rate of influent was 15 kg COD/$m^3$/day. Since organic loading rate was up to 20 kg COD/$m^3$/day, the removal rate declined 80.7%. Over loading of influent caused sludge expansion and overproduction of microorganism. Amount of biogas was collected 82.3 L/day and pH was remained 6.9 constantly with balance of alkalinity.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.4
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• pp.78-85
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• 2000

Leachate from acidogenic fermentation of food waste was effectively treated by the UASB reactor at $37^{\circ}C$. The efficiency of COD removal was consistently over 96% up to the loading rates of $15.8g\;COD/{\ell}{\cdot}d$. The methane production rate increased to $5.5{\ell}/{\ell}{\cdot}d$. Of all the COD removed, 92% was converted to methane and the rest presumably to biomass. At loading rates over $18.7g\;COD/{\ell}{\cdot}d$, the efficiency of COD removal decreased due to the sludge flotation and washout in the reactor, which resulted from short HRT of less than 10.6 hr. The SMA(specific methanogenic activity) analysis showed that the VFA-degrading activity of granule was the highest for butyrate, and the lowest for propionate. This result was consistent with the observation that the residual propionate concentration was the highest among the VFAs in the effluent. Typical granules were found to be mainly composed of microcolonies of Methanosaeta. Though the original seed sludge contained 64.3% of particles smaller than 1.4mm, the sludge particles had been growing during the fermentation, and at the final step of this study, 75.1% of the particles were found to be larger than 1.4 mm in the UASB reactor.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.210-213
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• 2008

The purpose of this study is to investigate the performances of organic removal and methane recovery in the full scale two-phase anaerobic system. The full scale two-phase anaerobic system was consists of an acidogenic ABR (Anaerobic Baffled Reactor) and a methanognic UASB (Upflow Anaerobic Sludge Blanket) reactor. The volume of acidogenic and methanogenic reactors is designed to 28.3 $m^3$ and 75.3 $m^3$. The two-phase anaerobic system represented 60-82% of COD removal efficiency when the influent COD concentration was in the range of 7,150 to 16,270 mg/L after screening (average concentration is 10,280 mg/L). After steady-state, the effluent COD concentration in the methanogenic reactor showed 2,740 $\pm$ 330 mg/L by representing average COD removal efficiency was 71.4 $\pm$ 8.1% when the operating temperature was in the range of 19-32$^{\circ}C$. The effluent SCOD concentration was in the range of 2,000-3,000 mg/L at the steady state while the volatile fatty concentration was not detected in the effluent. Meanwhile, the COD removal efficiency in the acidogenic reactor showed less than 5%. The acidogenic reactor played key roles to reduce a shock-loading when periodic shock loading was applied and to acidify influent organics. Due to the high concentration of alkalinity and high pH in the effluent of the methanogenic reactor, over 80% of methane in the biogas was produced consistently. More than 70 % of methane was recovered from theoretical methane production of TCOD removed in this research. The produced gas can be directly used as a heat source to increase the reactor temperature.

• Journal of Korean Society on Water Environment
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• v.21 no.3
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• pp.256-262
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• 2005

The purpose of this study is to investigate the performances of organic removal and methane recovery by using a full scale two-phase anaerobic system. The full scale two-phase anaerobic process was consists of an acidogenic anaerobic baffled reactor (ABR) and a methanognic upflow anaerobic sludge blanket (UASB) reactor. The volumes of acidogenic and methanogenic reactors were designed to $28.3m^3$ and $75.3m^3$. The two-phase anaerobic system represented 60-82% of COD removal efficiency when the influent COD concentration was in the range of 7,150 to 16,270 mg/L after screening (average concentration is 10,280 mg/L). After steady-state, the effluent COD concentration in the methanogenic reactor showed $2,740{\pm}330 mg/L$ by representing average COD removal efficiency was $71.4{\pm}8.1%$ when the operating temperature was in the range of $19-32^{\circ}C$. The effluent SCOD concentration was in the range of 2,000-3,000 mg/L at the steady state while the volatile fatty acid concentration was not detected in the effluent. Meanwhile, the COD removal efficiency in the acidogenic reactor showed less than 5%. The acidogenic reactor played key roles to reduce a shock-loading when periodic shock loading was applied and to acidify influent organics. Due to the high concentration of alkalinity and high pH in the effluent of the methanogenic reactor, over 80% of methane in the biogas was produced consistently. More than 70% of methane was recovered from theoretical methane production of TCOD removed in this research. The produced gas can be directly used as a heat source to increase the reactor temperature.

• Journal of environmental and Sanitary engineering
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• v.12 no.3
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• pp.9-17
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• 1997

This research aims to remove nitrogen in the piggery wastewater by combined process with upflow anaerobic sludge blanket (UASB) and biofilm process. For the effective denitrification. anaerobic and anoxic reactors were connected to a reactor. The effluent of aerobix reactor was recycled equally with influent in the upper filter of anaerobic reactor for denitrification and outlet of UBF reactor was connected to the settling tank with $1.5{\;}{\ell}$ capacity and the settling sludge was repeatedly recycled to UASB zone. The organic loading rate of total reactor was operated from 0.4 to $3.1kgCOD/m^{3}/d$ and it was observed that the removal rate of TCOD was 80 to 95 percentage. Ammonia nitrogen was removed over 90 percentage in the less volumetric loading rate than $0.1{\;}kgN/m^{3}/d$. But because of non-limitation of organic materials, it was reduced to 70 percentage in the more volumetric loading rate than $0.6{\;}kgN/m^{3}/d$. But denitrification rate was observed 100 percentage in the all of loading rate. This is caused by the maintenance of optimum temperature, sufficient carbon source, and competition of electron acceptors. The results of COD mass balance at the $1.21{\;}kgCOD/m^{3}/d$ was observed with the 71.7% percentage of influent COD. It was revealed that the most part of organic materials was removed in the aerobic and the anaerobic reactor because 38.4 percentage was conversed into $CH_{4}$ gas and 11 percentage was removed in the aerobic reactor with cell synthesis and metabolism. Besides, 5.7% organics was used to denitrification reaction and 3.7% organics related to sulfate reduction.