• 한국경영과학회지
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• 제15권1호
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• pp.37-46
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• 1990

Biomass to methane production is a good supply of substitutable energy resources. The economic viability of these systems depends a great deal on cost effective production methods and facilities. The operational problem is to determine the time eto allocate to each batch of several feedstocks for each digester and to determine the number of batches for each digester so as to maximize biogas production for two identical digesters over a fixed planning horizon. This paper provides an efficient approximation procedure which is based on decomposition of the problem and the analysis of incremental gas production function for each feedstock. The computational experience for the heuristic procedure was also reported.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.745-748
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• 2000

Anaerobic digester coupled with hollow fiber membrane unit. Treatment of starch waste with anaerobic digester-membrane system was studied. $0.17\;m^2$ area of hollow fiber membrane unit of known pore size was immersed into laboratory-scale anaerobic digestion system. The gas production was about $0.74\;m^3/kg$ COD treated. The COD removal efficient was about 80-95% depending on the hydraulic retention time. Crossflow ultrafiltration as Post treatment to anaerobic filter. The study conducted with different membrane pore size indicated that membrane with 1,000,000 molecular weight cut-off size gave a higher COD removal efficiency in the range of 83-87% while giving a study flux of $120-130\;L/m^2\;{\cdot}\;h$. A study was conducted to see the long term clogging effect of membrane also.

• 한국환경보건학회지
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• 제14권2호
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• pp.43-49
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• 1988

This study was conducted to evaluate the organic removal efficiencies and sludge production in aerobic and anaerobic digestion of swine manure. A laboratory single-stage, high-rate, anaerobic digester was operated at 5, 10, 25 and 30 day's HRT at the temperature of 35$\circ$C, and also aerobic digester operated at 10, 20 and 28.6 day's HRT at the temperature of 20$\circ$C. The conclusions from this study are as follows: 1. While the BOD removal efficiency by anaerobic digestion was 30 to 75%, it was 99% over by aerobic digestion. 2. The sludge production was similar in both aerobic and anaerobic digestion. 3. The gas production was 0.21 to 0.55 m$^3$/kg VS fed by anaerobic digestion.

• Korean Journal of Hydrosciences
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• 제2권
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• pp.115-126
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• 1991

The anaerobic digester with sludge from sewage treatment plant was operated in the laboratory for two year to investigate the enumeration and activity of methanogenic microorganisms. In this experimental study, the effects of HRT on the degradation characteristics of organic materials and on the number of methanogenic bacteria produced were investigated. By making the media with the repeated wxperiment, the number and activity of methanogenic bacteria were measured. The increase of the removal rate of organic acid in the digester was oberved at HRT of 2 days. The total number of methane forming bacteria estimated by the MPN method showed 2.3 $\times$ $ at HRT of 3 days, 7$\times$$ of 5 days and 7.9$\times$$ $/ml of 10 days. The optimum incubation time for measuring the number of methanogenic bacteria was found as more than four weeks. The PMA revealed 161ml CH$/l day at HRT of 10 days and the PUA 290mg COD/l day. At the incubation time 4.3 days, the maximum value of CH$ *59.1%) was found. At this time, $ was found as 15.3% and $ 25.6%.

• Journal of Forest and Environmental Science
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• 제29권2호
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• pp.125-130
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• 2013

An attempt was made on pulp production from the fast growing plant, Acacia hybrid to determine the total yield, screened yield, Kappa number, and fibre morphology of organosolv Acacia hybrid pulp. Uniform-sized chips were taken to undergo pulping in a digester with five different concentrations of ethanol, 50%, 60%, 70%, 80% and 90% (v/v) with 1 M of sodium hydroxide as catalyst. All chips were digested in a temperature-controlled digester with constant amount of water added and temperature of $185^{\circ}C$ with the duration of three hours cooking time and correspond pressure 1.1-1.2 MPa. It was observed that increasing of ethanol concentration has led to pulp yield increment and decreased in the degree of delignification at the same time. This study was aimed to focus on the effect of the varied concentration of organic solvent towards the pulp yield and its relationship with Kappa number and pulp yield.

• Nuclear Engineering and Technology
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• 제52권1호
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• pp.170-177
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• 2020

A mixer with a new concept design has been adapted into water treatment plants. It reportedly cuts down the energy consumption of the mixer by the new mixer, which moves vertically and creates internal flows toward its bottom. However, no experimental observations have been made on the internal flow caused by a vertical impeller. In this study, a radiotracer experiment, radioactive particle tracking (RPT) technique, and particle image velocimetry (PIV) were carried out to visualize the flow in the mixer, and compared to each other. The results show that the flow patterns from these techniques are very similar to each other, and the performance of the mixer was good enough to mix the inner materials.

• 한국물환경학회지
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• 제16권4호
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• pp.541-554
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• 2000

Experimental study of anaerobic digestion process combined with and without the submerged separation membrane was investigated by using laboratory-scale reactor at the hydraulic retention time of 0.5 day and 1.0 day. The removal efficiencies of carbohydrate at the digester without and with membrane were 84.4 to 86.8 % and 99.6 to 99.7 %, respectively, and the methane gas recovery efficiencies were 0.4 to 1.2 % and 12.3 to 28.7 %. According to the measurement by the most probable numbers method. the numbers of various groups of bacteria in the digesters with membrane were enumerated in the following ranges ; acidogens : $1.7{\times}10^9$ to $5.0{\times}10^9MPN/m{\ell}$, homoacetogens : $5.0{\times}10^7$ to $2.4{\times}10^8MPN/m{\ell}$, $H_2$-utilizing methanogens : $1.3{\times}10^7$ to $9.2{\times}10^8MPN/m{\ell}$, and acetate-utilizing methanogens : $2.3{\times}10^6$ to $2.0{\times}10^8MPN/m{\ell}$. The number of methanogens at the digester with membrane increased by approximately $10^2$ to $10^4$ times in comparison with that of the digester without membrane.

• 한국토양비료학회지
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• 제50권4호
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• pp.293-305
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• 2017

This experiment was conducted to evaluate the effect of leachate replacement frequency on solid state anaerobic digestion (SSAD) of dairy manure using 22 L volume lab-scale digesters at mesophilic temperature ($37^{\circ}C$) in batch mode. Three different leachate replacement strategies (no replacement, once every three days, and once every nine days) were applied and three digesters per each treatment were operated for 45 days. Results showed that leachate replacement test unit every nine days resulted in 1.6 times more methane production ($53.8N{\cdot}mL\;g^{-1}{\cdot}VS$) from SSAD compared to test unit every three days ($34.0N{\cdot}mL\;g^{-1}{\cdot}VS$). No leachate replacement strategy applied group showed slightly higher methane production ($56.3N{\cdot}mL\;g^{-1}{\cdot}VS$) than every nine days replaced one. When added the methane production potential of replaced leachate itself to the methane produced from digester, leachate replacement every nine days resulted in quite similar methane production ($56.5N{\cdot}mL\;g^{-1}{\cdot}VS$) to no leachate replacement group. Even though methane production potential of replaced leachate itself added to the methane produced from digester, every three days replacement showed only $34N{\cdot}mL$ methane production per gram of volatile solids. These results suggest that farmers do not need to replace leachate during SSAD of dairy manure and sawdust mixture in order to maximize methane production. If there are any concerns with accumulation of inhibiting substances in the digester, the 9-day cycle leachate replacement is appropriate.

• Asian-Australasian Journal of Animal Sciences
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• 제29권4호
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• pp.586-593
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• 2016

A new methanogen was isolated from an anaerobic digester using pig slurry in South Korea. Only one strain, designated KOR-1, was characterized in detail. Cells of KOR-1 were straight or crooked rods, non-motile, 5 to $15{\mu}m$ long and $0.7{\mu}m$ wide. They stained Gram-positive and produced methane from $H_2+CO_2$ and formate. Strain KOR-1 grew optimally at $38^{\circ}C$. The optimum pH for growth was 7.0. The strain grew at 0.5% to 3.0% NaCl, with optimum growth at 2.5% NaCl. The G+C content of genomic DNA of strain KOR-1 was 41 mol%. The strain tolerated ampicillin, penicillin G, kanamycin and streptomycin but tetracycline inhibited cell growth. A large fragment of the 16S rRNA gene (~1,350 bp) was obtained from the isolate and sequenced. Comparison of 16S rRNA genes revealed that strain KOR-1 is related to Methanobacterium formicicum (98%, sequence similarity), Methanobacterium bryantii (95%) and Methanobacterium ivanovii (93%). Phylogenetic analysis of the deduced mcrA gene sequences confirmed the closest relative as based on mcrA gene sequence analysis was Methanobacterium formicicum strain (97% nucleic acid sequence identity). On the basis of physiological and phylogenetic characteristics, strain KOR-1 is proposed as a new strain within the genus Methanobacterium, Methanobacterium formicicum KOR-1.

• 상하수도학회지
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• 제29권2호
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• pp.203-209
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• 2015

The purpose of this study is to estimate the applicability of a stable anaerobic digester using a separator membrane to the preprocessing thickening process. The results of the experiments showed about a 47.16% weight loss rate for the sludge under anaerobic condition, and about 41.17% under intermittent aeration condition. The concentrations of rejection water were $SCOD_{Cr}$ 25 mg/L, T-N 16.6 mg/L, and T-P 1.4 mg/L on the average under the intermittent aeration condition, which were lower than the concentrations of rejection water under an anaerobic condition. As for the factors affecting the reduction of the flux, correlation analyses of TTF, MLSS, $SCOD_{Cr}$, and $EPS_{Protein}$, $EPS_{Polysacchride}$ resulted in -0.97, -0.95, -0.84 and -0.86, -0.95, respectively, which showed that TTF had the highest correlation to the reduction of the flux. In addition, it was concluded that MLSS, $SCOD_{Cr}$ and $EPS_{Protein}$, $EPS_{Polysacchride}$ also have close correlations. The results are considered to show that, in the case of the process using a tubular membrane in the preprocessing process of an anaerobic digester, an intermittent aeration condition of the thickener considering the contamination of the membrane and load of rejection water is appropriate for the stable preprocessing process.