• Environmental Engineering Research
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• v.19 no.1
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• pp.83-89
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• 2014

The effects of initial solid concentration and microwave irradiation (MWI) time on the hydrolysis of waste activated sludge (WAS) were investigated. MWI time strongly influenced WAS hydrolysis for all initial solid concentrations of 8.20, 31.51, and 52.88 g VSS/L. For all WAS, the volatile suspended solids (VSS) solubilization degree ranged from 35.6% to 38.4% during a total MWI time of 10 min. Soluble chemical oxygen demand (SCOD) concentration increased at a rate proportional to the decrease of VSS during the MWI. However, the clearly different VSS solubilization patterns that were observed during the MWI were explained by the 2-step hydrolysis of WAS, consisting of the initial disintegration of the easily degradable part of the sludge, followed by the subsequent disintegration of the hardly degradable part of the sludge. WAS hydrolysis rates for 3 to 6 min of MWI were significantly lower than those for less than 3 min, or more than 6 min. From these results, 3 min MWI time and WAS of 31.51 g VSS/L (centrifugal thickener WAS) showed the most efficient hydrolysis of WAS at 36.0%. The profiles of total nitrogen (T-N) concentrations corresponded well to the SCOD increases in terms of the empirical formula of bacterial cell mass ($C_5H_7O_2N$). The negligible T-N increase and pH decrease during WAS hydrolysis by MWI will allow the application of this process to subsequent biological processes, such as anaerobic digestion.

• Journal of Plant Biology
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• v.28 no.3
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• pp.233-241
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• 1985

The isolation and culture of protoplasts from hypocotyl-derived calluses of Glycine max (L.) Merr. cv. Jangyeop were obtained by digestion for 6 hrs in an enzyme solution containing 3.5% cellulase, 1.5% macerozyme, 10% sorbitol and 0.1% CaCl2.2H2O at pH 5.8. Newly formed cell wall of protoplasts cultured in MS agar medium containing 10 $\mu$M $\alpha$-naphthaleneacetic acid (NAA) and 32 $\mu$M N6-benzylaminopurine (BAP) could be observed after 24 hrs culture. The first cell division of the protoplasts was observed after 3 days of culture; cell clusters after 2 weeks of culture. When transferred to solid media, the protoplasts formed cell clusters gave rise to proliferating calluses.

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.1
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• pp.23-31
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• 2003

A mathematical model was formulated to simulate the long-term performance of an anaerobic bioreactor designed to digest Korean food wastes. The system variables of various decomposition steps were built into the model, which predicts the temporal characters of Solid waste, and volatile fatty acid (VFA) in the reactor, and gas production in response to various input loadings and temperatures. The predicted values of VFA and gas production were found to be in good agreement with experimental observations in batch and repeated-input systems. Finally, long-term reactor performance was simulated with respect to the seasonal temperature changes from 5C in winter to 25C in Summer at different food waste input loadings. The simulation results provided us with information concerning the success or failure of a process during long-term operation .

• Journal of Environmental Science International
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• v.15 no.10
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• pp.975-982
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• 2006

This study has been conducted to optimum operating conditions for effective acid fermentation according to OLR(organic loading rate) in the mesophilic and thermophilic acid fermentation process. The results are summarized as follows. In order to obtain reasonable acid fermentation efficiency in performing acid fermentation of food wastes in thermophilic condition, organic loading rate was required below 20 gVS/L.d. As $SCOD_{Cr}/TKN,\;SCOD_{Cr}/T-P$ of thermophilic acid fermented food wastes In organic loading rate 20 gVS/L.d were 18.9, 73.4 respectively, it was possible to utilize as external carbon source for denitrification in sewage treatment plant after solid-liquid separation as well as co-digestion of fermented food wastes and sewage sludge.

• Journal of Microbiology and Biotechnology
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• v.27 no.10
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• pp.1808-1819
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• 2017

Knowledge on the functional characteristics and temporal variation of anaerobic bacterial populations is important for better understanding of the microbial process of two-stage anaerobic reactors. However, owing to the high diversity of anaerobic bacteria, close attention should be prioritized to the frequently abundant bacteria that were defined as core bacteria and putatively functionally important. In this study, using MiSeq sequencing technology, the core bacterial community of 98 operational taxonomic units (OTUs) was determined in a two-stage upflow blanket filter reactor treating pharmaceutical wastewater. The core bacterial community accounted for 61.66% of the total sequences and accurately predicted the sample location in the principal coordinates analysis scatter plot as the total bacterial OTUs did. The core bacterial community in the first-stage (FS) and second-stage (SS) reactors were generally distinct, in that the FS core bacterial community was indicated to be more related to a higher-level fermentation process, and the SS core bacterial community contained more microbes in syntrophic cooperation with methanogens. Moreover, the different responses of the FS and SS core bacterial communities to the temperature shock and influent disturbance caused by solid contamination were fully investigated. Co-occurring analysis at the Order level implied that Bacteroidales, Selenomonadales, Anaerolineales, Syneristales, and Thermotogales might play key roles in anaerobic digestion due to their high abundance and tight correlation with other microbes. These findings advance our knowledge about the core bacterial community and its temporal variability for future comparative research and improvement of the two-stage anaerobic system operation.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.515-523
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• 2012

The study investigated the biochemical methane potential (BMP) assay of cellulose supplementing with mixed methanogens and cellulolytic bacteria to improve anaerobic digestion for methane production. For the BMP assay, 7 different microbial supplementation groups were consisted of the cultures of mixed methanogens (M), Fibrobacter succinogenes (FS), Ruminococcus flavefaciensn (RF), R. albus (RA), RA+FS and M+RA+FS including control. The cultures were added in the batch reactors with the increasing dose levels of 1% (0.5 mL), 3% (1.5 mL) and 5% (2.5 mL). Incubation for the BMP assay was carried out for 40 days at $38^{\circ}C$ and anaerobic digestate obtained from an anaerobic digester with pig slurry as inoculum was used. In results, 5% FS increased total biogas and methane production up to 10.4~22.7% and 17.4~27.5%, respectively, compared to other groups (p<0.05). Total solid (TS) digestion efficiency showed a similar trend to the total biogas and methane productions. Generally the TS digestion efficiency of the FS group was higher than that of other groups showing at the highest value of 64.2% in the 5% FS group. Volatile solid (VS) digestion efficiencies of 68.4 and 71.0% in the 5% FS and the 5% RF were higher than other groups. After incubation, pH values in all treatment groups were over 6.4 indicating that methanogensis was not inhibited during the incubation. In conclusion, the results indicated that the hydrolysis stage for methane production in anaerobic batch reactors was the late-limiting stage compared with the methanogenesis stage, and especially, as the supplementation levels of F. succinogenes supplementation increased, the methane production was increased in the BMP assay compared with other microbial culture addition.

• Journal of the Korea Organic Resources Recycling Association
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• v.1 no.1
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• pp.103-113
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• 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.

• Journal of Digital Convergence
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• v.10 no.10
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• pp.221-227
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• 2012

In Korea, ocean dumping has been widely used as the ultimate disposal of sewage sludge. However, ocean dumping of food wasted and sewage sludge from 2013 is expected to legally restricted as London convention on marine pollution prevention has been effective in 2009. This research aims to examine the effect of HEAS in treating the environmental pollution load caused by organic high concentrated sludge. Thus, onsite laboratory scale treatability test using HEAS was adopted to treat the high concentrated organic sludge from sewage and industrial wastewater treatment plant. The research results showed that the HEAS is useful to reduce the environmental pollution caused by organic high concentrated sludge. Specific results are as follows. 1. The organic removal after the sludge digestion using the high efficiency aeration system was 55.2-85.8%. Although these results were lower than those from the general sewage treatment, the high efficiency aeration system could be evaluated as efficient, considering the object sludge contained the industrial waster water. 2. The average removal efficiency was about 25.2%. 3. It was revealed that sludge digestion by the high efficiency aeration system could effectively contribute to the sludge treatment cost. Especially, the high efficiency aeration system is more applicable to the onsite treatment of small sewage and wastewater treatment plant that contains high solid content sludge, industrial wastewater sludge, high fixed solid sludge.

• Analytical Science and Technology
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• v.16 no.2
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• pp.102-109
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• 2003

Microwave digestion and solid-state extraction were studied for determination of trace aluminum{Al(III)} in human urine samples. A mixed acid of nitric acid and hydrogen peroxide was added to urine samples, organic materials were destructed in a home microwave oven and dried in a drying oven. The dried residues were dissolved in a sulfuric acid solution. The solution was eluted through a XAD-4 resin column adsorbed with 8-hydroxyquinoline(Oxine, HQ). Al(III)-8-hydroxyquinolinate complex was formed in the column and eluted with 0.5 M nitric acid solution. The Al(III) eluted was determined by graphite atomic absorption spectrophotometry. Various experimental conditions of followings were investigated for the optimization : the type of acid to dissolve the residues, the amount of HQ adsorbed on the resin, the pH of sample solutions, the type and concentration of acid to elute the complex from column and so on. The contents of Al(III) in real samples were determinated by a calibration curve method. The recovery in standard spiked samples was 94~101% and the detection limit of this procedure was 0.05 ng/mL.

• Korean Journal of Environmental Agriculture
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• v.29 no.2
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• pp.197-205
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• 2010

This study was conducted to investigate the optimum conditions for efficient methane production through anaerobic digestion of pig waste slurry. The examined parameters were organic matter content of the pig slurry, the ratio of seed sludge to pig slurry, and stirring intensity of the digestion reactor. The effects of types of slurry produced from different purpose-based pigs fed with different feeds were also tested. The methane concentration in the produced biogas was 45% when the ratio of seed sludge to pig slurry was 50% and total solid (TS) concentration was 1%, and it increased in proportional to TS concentration increases from 3 to 7%. At 3 and 5% of TS concentration, increasing mixing velocity from 80 to 160 rpm resulted in higher biogas production amount. However, mixing amount of seed sludge did not cause any significant effect on biogas production. Overall, the most efficient biogas production was achieved at 3-5% TS concentration in combination with 50% seed sludge inoculation and mixing velocity at 120 rpm. Among pig slurry types, gestating sow waste slurry showed the highest biogas production probably due to higher the degradation rate than other types of pig waste slurry being affected by the feeds components.