• Korean Journal of Soil Science and Fertilizer
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• v.47 no.2
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• pp.127-132
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• 2014

The effect of thermal pretreatment conditions on hydrolysis characteristics of dairy manure and sawdust mixtures has been evaluated. Thermal pretreatment temperature varied between 35 and $120^{\circ}C$ and the period of the treatment changed between 30 and 1440min (24h). As thermal pretreatment temperature and duration increased, organic material solublization rates were improved. Maximum solubilizations of chemical oxygen demand (SCOD), carbohydrates, and volatile fatty acids(VFAs) were observed when dairy manure treated for one day at $120^{\circ}C$. Although one day treatment duration at $120^{\circ}C$ showed the highest SCOD, soluble carbohydrates, and VFAs concentration, its hydrolysis rate was only about 12%. The results reveal that the thermal pretreatment conditions tried in this study are not enough to solubilize the organic matter contained in dairy manure and sawdust mixtures. In order to maximize hydrolysis performance, the further research needs to determine the factors influences on organic material solubilization in addition to thermal pretreatment temperature and duration.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.5
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• pp.409-415
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• 2015

This study was performed to optimize the integrated anaerobic digestion (AD) and microbial electrolysis cells (MECs) for the enhanced hydrogen production. The optimum operational conditions of integrated AD and MECs were obtained using response surface methodology. The optimum substrate concentration and operational pH were 10 g/L and 6.8, respectively. In the confirm test, 1.43 mol $H_2/mol$ hexose was achieved, which was 2.5 times higher than only AD. After 40 to 60 hour at seeding, the volatile fatty acids (VFAs) in reactor of AD were not changed. However the VFAs of reactor of AD-MECs were reduced by 61.3% (acetate: 76.4%, butyrate: 50.0%, lactate: 55.0%).

• Environmental Engineering Research
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• v.10 no.1
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• pp.7-14
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• 2005

The feasibility of hydrogen production with a raw seed sludge through direct acclimation of feedstock was investigated at acidogenic stage, and methane was harvested at followed methanogenic stage in an anaerobic two-stage process. Hydrogen content was higher than 57% at all tested organic loading rates (OLRs) and the yield of hydrogen ranged from 1.5 to 2.4 mol H2/mol hexose consumed and peaked at 6 gVSl-1day-1. Normal butyrate and acetate were main volatile fatty acids (VFAs), whereas the concentration of propionate was insignificant. The hydrogen-producing bacteria, Clostridium thermosaccharolyticum, was detected with strong intensity at all tested organic loading rates (OLRs) by denaturing gradient gel electrophoresis (DGGE) of the polymerase chain reaction (PCR) analysis. From COD balance in the process, the fraction of the feed-COD converted to the hydrogen-COD at acidogenic stage ranged from 7.9% to 9.3% and peaked at 6 gVSl-1day-1, whereas the fraction of feed-COD converted to the methane-COD at methanogenic stage ranged from 66.2% to 72.3% and peaked at 3 gVSl-1day-1.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.1
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• pp.58-72
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• 2009

In this study, the organic matter and biomass was characterized by using respirometry based on ASM No.2d (Activated Sludge Model No.2d). The activated sludge models are based on the ASM No.2d model, published by the IAWQ(International Association on Water Quality) task group on mathematical modeling for design and operation of biological wastewater treatment processes. For this study, OUR(Oxygen Uptake Rate) measurements were made on filtered as well as non-filtered wastewater. Also, GC-FID and LC analysis were applied for the estimation of VFAs(Volatile Fatty Acids) COD(S_A) in slowly bio-degradable soluble substrates of the ASM No.2d. Therefore, this study was intended to clearly identify slowly bio-degradable dissolved materials(S_S) and particulate materials(X_I). In addition, a method capable of determining the accurate time to measure non-biodegradable COD(S_I), by the change of transition graphs in the process of measuring microbial OUR, was presented in this study. Influent fractionation is a critical step in the model calibrations. From the results of respirometry on filtered wastewater, the fraction of fermentable and readily biodegradable organic matter(S_F), fermentation products(S_A), inert soluble matter(S_I), slowly biodegradable matter(X_S) and inert particular matter(X_I) was 33.2%, 14.1%, 6.9%, 34.7%, 5.8%, respectively. The active heterotrophic biomass fraction(X_H) was about 5.3%.

• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.2
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• pp.55-69
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• 2011

Use of disposer at the kitchens of Korean apartments is inevitable in treating their foodwaste having a water content of more than 80%. Also we have to ensure that this extra disposer-foodwaste BOD loadings be treated properly by installing/operating a pre-treatment system before this wastewater enters public sewer system. However, the degree of BOD removal should not be excessive since a BOD/N ratio higher than 5 is required for removing N/P at a municipal wastewater treatment plant. The removal of BOD/N in the pretreatment system rather than BOD alone can be an alternative solution in solving this problem. The particles separated by sedimentation, screen or packed-bed can be anaerobically digested at apartment sites to generate biogas that can be used for simple digester heating and to generate volatile fatty acids (VFAs) for nitrogen removal. We suggest that Korean government grants a temporary license (say for 5 years) to foodwaste treatment companies in collaboration with apartment construction companies which may do business and develop various kinds of disposer-foodwaste treatment systems in diverse wastewater discharge systems of Korean apartments.

• Journal of Animal Science and Technology
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• v.59 no.12
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• pp.28.1-28.8
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• 2017

Background: Major amino acids in pig diets are Lys, Met, Thr, and Trp, but little is known about the requirements for the other essential amino acids, especially on odorous compounds and microbial characteristics in feces of growing-finishing pigs. To this end, different levels of amino acid composition added to diets to investigate the effects of amino acid composition on microbial characteristics and odorous compounds concentration. Methods: A total eight (n = 8) barrows (Landrace ${\times}$ Yorkshire ${\times}$ Duroc) with an average bodyweight of $89.38{\pm}3.3kg$ were individually fed diets formulated by Korean Feeding Standards 2007 (old version) or 2012 (updated with ideal protein concept) in metabolism crates with two replication. After 15-day adaptation period, fresh faecal samples were collected directly from pigs every week for 4 weeks and analysed for total volatile fatty acids (VFA), phenols and indoles by using gas chromatography. The nitrogen was determined by Kjeldahl method. Bacterial communities were detected by using a 454 FLX titanium pyrosequencing system. Results: Level of VFA tended to be greater in 2012 than 2007 group. Among VFAs, 2012 group had greater (p < 0.05) level of short chain fatty acids (SCFA) than control.Concentration of odorous compounds in feces was also affected by amino acid composition in pig diet. Levels of ammonium and indoles tended to be higher in 2012 group when compared with 2007 group.Concentration of phenols, p-cresol, biochemical oxygen demand, and total Kjeldahl nitrogen, however, were lower (P < 0.05) in 2012 treatment group compare to 2007. The proportion of Firmicute phylum were decreased, while the Bacteriodetes phylum proportion increased and bacterial genera includingCoprococcus, Bacillus, and Bacteroides increased (p < 0.05) in 2012 compare to 2007 group. Conclusion: Results from our current study indicates that well balanced amino acid composition reduces odor by modulating the gut microbial community. Administration of pig diet formulated with the ideal protein concept may help improve gut fermentation as well as reduce the odor causing compounds in pig manure.

• Korean Journal of Environmental Agriculture
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• v.29 no.4
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• pp.348-353
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• 2010

The current study investigated the fate of organic matter in piggery slurry under two different store systems(closed store system and open store system) in association with different temperature. Thirty days after storing in both systems at $20^{\circ}C$, it was observed that the content of organic matter remained in piggery slurry with closed store system was twice more than that with open store system implying more efficient degradation of organic matter with open store system. Temperature also influenced on the organic matter degradation in piggery slurry as shown decline in TS and VS contents as the temperature increased. With store at $35^{\circ}C$, 29% of initial organic matter was reduced while there was only 23% reduction of organic matter at $20^{\circ}C$. There was no difference in the type of organic fatty acids(VFAs) produced under the range of temperature(20, $35^{\circ}C$) simulating summer condition. Increases in organic fatty acids contents with hydrolysis and acid producing microbial was observed from 15 days after initiating store of the piggery slurry and the total organic acid amount produced 30 days after store was $2,829\;mg{\cdot}COD/L$ and $9,123\;mg{\cdot}COD/L$ at $20^{\circ}C$ and $35^{\circ}C$, respectively. These corresponded to 5.4% and 17.4% of the initial organic matter contents in piggery slurry, respectively.

• Journal of Animal Science and Technology
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• v.62 no.5
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• pp.638-647
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• 2020

This study determined the substitution effects of rice for corn as the main grain source in a total mixed ration (TMR). In vitro rumen fermentation characteristics and microbes were assessed using two experimental diets. Diets included 33% dry matter (DM) of either corn (Corn TMR) or rice grains (Rice TMR). In a 48-h in vitro incubation, DM digestibility (IVDMD), neutral detergent fiber degradability (IVNDFD), crude protein digestibility (IVCPD), volatile fatty acids (VFAs), pH and ammonia nitrogen (NH₃-N) were estimated. Gas production has been calculated at 3, 6, 12, 24 and 48 h. Our results indicate that the gas production, VFAs, IVDMD, and IVNDFD of Rice TMR were higher than those of Corn TMR (p < 0.05). Ruminal pH and total fungi were significantly higher in Corn TMR (p < 0.05) than in Rice TMR; however, NH₃-N and IVCPD were not affected by treatment type. In conclusion, substituting rice for corn at 33% DM in TMR appears to have no negative effects on in vitro rumen fermentation characteristics. Therefore, rice grains are an appropriate alternative energy source in early fattening stage diets of beef cattle.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.12
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• pp.1721-1725
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• 2014

The objective of this study was to evaluate the in vitro effects of coconut materials on ruminal methanogenesis and fermentation characteristics, in particular their effectiveness for mitigating ruminal methanogenesis. Fistulated Holstein cows were used as the donor of rumen fluid. Coconut materials were added to an in vitro fermentation incubated with rumen fluid-buffer mixture and timothy substrate for 24 h incubation. Total gas production, gas profiles, total volatile fatty acids (tVFAs) and the ruminal methanogens diversity were measured. Although gas profiles in added coconut oil and coconut powder were not significantly different, in vitro ruminal methane production was decreased with the level of reduction between 15% and 19% as compared to control, respectively. Coconut oil and coconut powder also inhibited gas production. The tVFAs concentration was increased by coconut materials, but was not affected significantly as compared to control. Acetate concentration was significantly lower (p<0.05), while propionate was significantly higher (p<0.05) by addition of the coconut materials than that of the control. The acetate:propionate ratio was significantly lowered with addition of coconut oil and coconut powder (p<0.05). The methanogens and ciliate-associated methanogens in all added coconut materials were shown to decrease as compared with control. This study showed that ciliate-associated methanogens diversity was reduced by more than 50% in both coconut oil and coconut powder treatments. In conclusion, these results indicate that coconut powder is a potential agent for decreasing in vitro ruminal methane production and as effective as coconut oil.

• Journal of Microbiology and Biotechnology
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• v.22 no.3
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• pp.400-406
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• 2012

To improve the hydrogen yield from biological fermentation of organic wastewater, a co-culture system of dark- and photo-fermentation bacteria was investigated. In a pure-culture system of the dark-fermentation bacterium Clostridium butyricum, a pH of 6.25 was found to be optimal, resulting in a hydrogen production rate of 18.7 ml-$H_2/l/h$. On the other hand, the photosynthetic bacterium Rhodobacter sphaeroides could produce the most hydrogen at 1.81mol-$H_2/mol$-glucose at pH 7.0. The maximum specific growth rate of R. sphaeroides was determined to be 2.93 $h^{-1}$ when acetic acid was used as the carbon source, a result that was significantly higher than that obtained using either glucose or a mixture of volatile fatty acids (VFAs). Acetic acid best supported R. sphaeroides cell growth but not hydrogen production. In the co-culture system with glucose, hydrogen could be steadily produced without any lag phase. There were distinguishable inflection points in a plot of accumulated hydrogen over time, resulting from the dynamic production or consumption of VFAs by the interaction between the dark- and photo-fermentation bacteria. Lastly, the hydrogen production rate of a repeated fed-batch run was 15.9 ml-$H_2/l/h$, which was achievable in a sustainable manner.