• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.679-688
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• 1994

Physicochemical and morphological characteristics of biopellets produced in "control" and modified UASB reactor were investigated to compare the reactor performance with regard to the hydrogen partial pressure. The characteristics of biopellet produced in modified UASB reactor operated with high hydrogen partial pressure were better than those of "control" reactor operated with relatively lower hydrogen partial pressure, therefore the hydrogen partial pressure effected greatly on the formation and stability of the biopellet. Furthermore, pellets from the UASB system with modified settler showed a better settleability and biomass holding capacity. The chemical composition of biopellet was distinctively different from that of common bacterial formula, $C_5H_7O_2N$. Biopellets was composed the large fraction of nitrogen in comparison with common anaerobic microbes. These results implicated the existence possibility of polypeptide-type extracellular polymer. The morphological characterization with SEM showed that microorganisms observed at surface of biopellet produced in modified UASB reactor operated with high $P_{H_2}$ condition were very similar in shape and size to the Methanobrevibactor arboriphilus-$H_2$ utilizing methanogen. The microorganisms was distinguished from those of "control" reactor operated with low $P_{H_2}$ condition. From these results, it could be explained the hydrogen partial pressure effects on pelletization mechanism.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.6
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• pp.279-290
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• 2016

The performance of upflow anaerobic bioelectrochemical reactor (UABE), equipped with electrodes (anode and cathode) inside the upflow anaerobic reactor, was compared to that of upflow anaerobic sludge blanket (UASB) reactor for the treatment of acidic distillery wastewater. The UASB was stable in pH, alkalinity and VFAs until the organic loading rate (OLR) of 4.0 g COD/L.d, but it became unstable over 4.0 g COD/L.d. As a response to the abrupt doubling in OLR, the perturbation in the state variables for the UABE was smaller, compared to the UASB, and quickly recovered. The UABE stability was better than the UASB at higher OLR of 4.0-8.0 g COD/L.d, and the UABE showed better performance in specific methane production rate (2,076mL $CH_4/L.d$), methane content in biogas (66.8%), and COD removal efficiency (82.3%) at 8.0 g COD/L.d than the UASB. The maximum methane yield in UABE was about 407mL/g $COD_r$ at 4.0 g COD/L.d, which was considerably higher than about $282mL/g\;COD_r$ in UASB. The rate limiting step for the bioelectrochemical reaction in UABE was the oxidation of organic matter on the anode surface, and the electrode reactions were considerably affected by the pH at 8.0 g COD/L.d of high OLR. The maximum energy efficiency of UABE was 99.5%, at 4.0 g COD/L.d of OLR. The UABE can be an advanced high rate anaerobic process for the treatment of acidic distillery wastewater.

• 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.

• Journal of the Korea Organic Resources Recycling Association
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• v.3 no.2
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• pp.37-45
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• 1995

The performance and the operational problems of UASB(Upflow Anaerobic Sludge Blanket) reactor for treatment of dairy wastewaters were investigated. Synthetic milk wastewater was successfully treated up to the loading rate of 3.9kg $COD/m^3.day$, with a specific gas production rate of 1. 23 I/I. day and a COD removal efficiency of over 90%. However, the sludge rising was observed at the loading rate of 2.1kg $COD/m^3.day$, due probably to the formation of scum layer at the surface of settling compartment. The BMP(biochemical methane potential) of raw milk wastewater and ice cream wastewater, measured by using SBT(serum bottle test), were 0.135 and 0.66ml $CH_4/mg\;COD_{added}$, respectively. The sludge activity increased more than 8 times from 0.159g $COD-CH_4/g$ VSS. d during 90 days of operation.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.981-987
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• 2000

Upflow anaerobic sludge blanket(UASB) reactor was operated for treating swine wastewater containing high ammonia nitrogen to assess their performance and toxicity of free ammonia concentration. In the reactor, chemical oxygen demand(COD) removed about 70% at $2.6kgCOD/m^3.day$ of organic loading rate(OLR) and 3 days of hydraulic retention time (HRT), while it was decreased when OLR and HRT was maintained $7kg\;COD/m^3.day$ and 2 days, respectively. Also UASB reactor was evaluated the activity of methane producing bacteria(MPB) according to change of free ammonia concentrations, MPB activity of applied sludge in the 500 and $1000mg-N/{\ell}$ of free ammonia concentration was inhibited by 4% and 40%, respectively. This clearly showed that free ammonia concentration less than $500mg-N/{\ell}$ showed no inhibition to MPB in anaerobic treatment of organics, UASB reactor was stabilized easily less than $1000mgVSS/{\ell}$ due to degradation of organic solids by the high activities of anaerobes.

• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.4
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• pp.151-160
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• 2006

Anaerobic treatment of landfill leachate was studied to investigate the behaviors of pollutant and the characteristics of microorganism for 10 months. The upflow anaerobic sludge blanket (UASB) reactor achieved about 90% chemical oxygen demand (COD) removal at organic loading rates(OLR) up to $20kgCOD/m^3.d$. At higher OLR ($8-20kgCOD/m^3.d$), the propionate concentration increased, indicating that converting propionate to acetate was the rate-limiting step. Nevertheless, increase in the precipitate inside and on the surface of granules as well as on the wall of the reactor resulted in operational problems. The main inorganic precipitate in the granule was calcium compound. Although specific methanogenic activity (SMA) was not affected seriously in this study, metals had to be removed prior to anaerobic treatment so as to be free from the excessive inorganic accumulation that resulted in operational problems.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.3
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• pp.75-82
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• 2008

Two UASB reactors were operated to investigate the effect of high concentration of sulfate on anaerobic digestion of propionate using an upflow anaerobic sludge blanket (UASB) reactor. An organic loading rate of $1.2kg\;COD/m^3{\cdot}d$ and a hydraulic retention time of 1.6 d were maintained during this study. In the absence of sulfate, the UASB reactor achieved about 95% removal of chemical oxygen demand whereas in the presence of $2,000\;SO_4^{2-}mg/L$, the COD removal rate decreased to 83% due probably to the inhibition of dissolved sulfide inhibition. Interactions between the methane producing bacteria (MPB) and sulfate reducing bacteria (SRB) were measured to investigate the competition between MPB and SRB. The MPB consumed average 58% of the available electron donors at $COD/SO_4^{2-}$ ratio of 1. Propionate was consumed mainly by SRB, converting sulfate into sulfide and suppressing the methane production. The specific methanogenic activity (SMA) using acetate and propionate increased as microorganism acclimated to the substrate.

• Journal of Environmental Health Sciences
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• v.32 no.2 s.89
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• pp.179-185
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• 2006

Effect of organic loading rate on UASB performance was evaluated under the renditions of some surface area/reactor volume ratio and different reactor diameter. At the low leading rate of 0.4 kg $COD/m^3{\cdot}d$, reactor performance was not affected by reactor diameter. At the organic loading rate of 6 kg $COD/m^3{\cdot}d$, however, volatile acid accumulation and low COD removal efficiency is observed in reactor having 6.4 cm diameter, while volatile acid is not accumulated at all and high COD removal efficiency is observed in reactor having 3 cm diameter. Such a difference of reactor performance depending on reactor diameter can be explained that sludge bed can be fluidized by evolved gas bubble in narrow reactor, while sludge bed ran not be fluidized by evolved gas bubble only in wide reactor. At a high organic loading rate of 20 kg $COD/m^3{\cdot}d$, it can be judged that there is no relation between reactor configuration and reactor performance because all reactors showed very low COD removal efficiencies regardless of reactor diameter. Narrow and tall type reactor is favorable condition for making sludge bed fluidization at a constant surface area/reactor volume ratio. Thus, it can be judged that reactor configuration and sludge bed fluidization have great influence to reactor performance.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.1
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• pp.49-57
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• 2009

This research examined the effect of ammonia nitrogen loading rate(NVLR) on the anaerobic digestion of slurry-typed swine wastewater. The anaerobic reactor was used an upflow anaerobic sludge blanket (UASB) process. This UASB reactor was operated at a NVLR of $0.02{\sim}0.96kg{NH_4}^+-N/m^3/day$. The methane content showed the range of 73.3~77.9% during the steady state period. Free ammonia(FA) concentration increased over inhibition level as pH increase from 7.3 to 8.2. However, in consideration of methane content, methane producing bacteria (MPB) inhibition by FA and total ammonia(TA) was not observed. A stepwise increase of the NVLR resulted in a deterioration in the COD removal rate in UASB reactor. The COD removal rate were 60% for NVLR up to $0.55kg{NH_4}^+-N/m^3/day$. As the NVLR increased from 0.09 to $0.96kg{NH_4}^+-N/m^3/day$, the biogas production rate varied from 3.71 to 9.14L/d and the methane conversion rate of the COD varied from 0.32 to $0.20m^3CH_4/kg$ COD removed. Consequently, in considerations of FA concentration, COD removal rate, and $CH_4$ production rate, the UASB reactor must be operated to lower than $0.40kg{NH_4}^+-N/m^3/day$ of NVLR.

• 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.