• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.1
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• pp.75-83
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• 2004

Temperature-phased anaerobic digestion (TPAD), anaerobic sequencing batch reactor (ASBR), and co-digestion technologies were combined together in order to overcome low efficiencies of conventional anaerobic sewage sludge digestion processes. In the performance, TPAD-ASBR process showed high VS removal efficiency over 60% up to the organic loading rate (OLR) of 2.7 g VS/L/d. The first-stage of TPAD-ASBR and control system played a most significant role in VS destruction and methane production. Methane production rate (0.79 l $CH_4/L/d$) of the system was higher than that (0.59 l $CH_4/L/d$) of the control system. The substrate characteristics of the sewage sludge, such as low VS concentration (1.5%, w/w) and biodegradability, were properly improved by the addition of food waste as a co-substrate, leading to more efficient VS removal and methane production. With several track studies, it was revealed that the independent solid retention time (SRT) of those systems prevented untreated particles from outflowing and also, extended the retention time of the active biomass for further degradation. Consequently, it was confirmed that the sequencing batch operation of the TPAD process using co-substrate was a promising alternative for the recycling of sewage sludge with low VS content.

• Journal of the Korea Organic Resources Recycling Association
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• v.30 no.4
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• pp.27-40
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• 2022

In this study, the anaerobic digestion potential and thermo-chemical pre-treatment were evaluated for efficient anaerobic co-digestion of dewatered sludge(DS) and food waste(FW). As a result, the degradable organic matter concentration and methane yield of FW were evaluated to 2.2 and 1.3 times higher than that of DS, respectively. In order to increase the amount of biogas production, it was determined that it is desirable to increase the mixing ratio of FW. The efficiency of thermo-chemical pre-treatment was evaluated for the reaction temperature, NaOH concentration, reaction time and mixture ratio. As a result of evaluation through pre-treatment efficiency and dehydration capacity, the optimum pre-treatment conditions were evaluated as follows: reaction temperature 140℃, NaOH concentration 60 meq/L, reaction time 60 min, mixture ratio 1:5(DS:FW). The gas production rate and methane yield increased 1.6 and 1.5 times, respectively, compared to before and after applying the optimum pre-treatment. Therefore, it is necessary to increase the mixing ratio of food waste for efficient anaerobic co-digestion of DS and FW. and it is necessary to increase the solubilization efficiency of waste by application of pre-treatment.

• Journal of Biosystems Engineering
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• v.43 no.1
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• pp.37-44
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• 2018

Purpose: The objective of this study was to investigate the high-efficiency anaerobic digestion of organic wastes with high fat content. Specifically, the analysis focused on biogas production performance with a focus on carbon number and the double bond count of the long-chain fatty acids (LCFAs), which are hydrolysis products of triglycerides. Methods: Experiments were performed under mesophilic anaerobic conditions with a feed-to-microorganism ratio (F/M) of 1.0. Biogas production performance was analyzed through biogas production patterns, lag-phase, and the time required for 90% biogas production (T90). Results: Biogas production increased when the content of unsaturated LCFAs (containing relatively large numbers of carbon atoms) increased. In substrate containing LCFAs with four or more double bonds, although the initial lag-phase in biogas production was shortened, development of a three-step lag-phase resulted in decreased biogas production. These results suggest that high rates of anaerobic digestion are possible when the LCFAs have high unsaturated fatty acid content with three or fewer double bonds. Conclusions: When various types of LCFAs are digested anaerobically, biogas production performance can be improved if the unsaturated fatty acid content and number of double bonds are optimized for maximum production.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.1
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• pp.21-27
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• 2012

This study evaluated the performance of a thermophilic two-phase anaerobic digestion (TTPAD) coupled with membrane process treating garbage leachate. The pilot-scale treatment system is consisted of thermophilic acidogenic reactor (TAR) and thermophilic methanogenic reactor (TMR) coupled with an ultrafiltration (UF) membrane unit. The hydraulic retention time of TAR and TMR were 4 and 20 days, respectively. Effluent TCOD and SCOD of the TTPAD were $25\;{\pm}\;6\;and\;12\;{\pm}\;3$ g/L, respectively, and the corresponding TCOD and SCOD removal efficiencies were 77% and 81%, respectively. Propionate was major acids as 75% in the effluent. Scum formation was not observed in TTPAD, which might be resulted from complete lipid degradation. However, TTPAD was appeared to be sensitive to free ammonia toxicity. The UF membrane was operated with constant pressure filtration at average TMP 1.3 atm. Permeate flux had a range of 15-30 $L/m^2/hr$. With UF membrane, TCOD removal increased from 77% to 93%, and this SS free effluent would be beneficial to subsequent processes such as ammonia stripping.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_1
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• pp.35-40
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• 2001

Effect of the addition of an enzyme/microbial additive(EMA) to enhance anaerobic digestion of the primary sludge was investigated. Two laboratory scale anaerobic digester were operated with primary sludge taken from a municipal wastewater treatment plant. The digester receiving EMA with the sludge feed performed better than the control digester, when both were operated at 10-days and 15-days Solid Retention Time(SRT). Addition of EMA to the experimental digester provided 7%(10-days SRT) and 16%(15-days SRT) higher gas production compared to the control digester when both were fed with the same amount of volatile solids. The reduction in volatile solids was 24% better in the experimental digester compared to the control ar 10-days SRT, and the improvement 10% at 15-day SRT. Improvement in COD reduction, and fecal coliform density reduction were also seen in the experimental digester due to EMA addition compared to the control both ar 10-days SRT and 15-day SRT operation. Preliminary cost benefit analysis for a wastewater treatment plant showed that approximately $115/day in gas production improvements can be realized upon addition of EMA to primary sludge anaerobic digesters operating at 10-day SRT. The value of increased gas production was $172/day if the same digesters are operated with EMA addition at 15-day SRT.

• Journal of Environmental Health Sciences
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• v.14 no.1
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• pp.63-71
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• 1988

This study is an experimental research on the anaerobic digestion of pig manure and night soil mixed waste at room temperature (25$\circ$C), and the results are shown below: 1. The steady-state condition based on gas production as digestion temperature dropped to 25$\circ$C from 35$\circ$C was achieved at around 28, 47, 56, 64 days respectively when its hydraulic retention time(HRT) are 10, 20, 30, 40 days. 2, Alkalinity and volatile acid(VA) was increased as increasing the organic loading. 3. Removal efficiency of chemical oxygen demand(COD) and biochemical oxygen demand (BOD) was improved as longer HRT, and generally COD value is lower and BOD value is higher relatively. 4. Overall treatment efficiencies of mixed waste are higher than of pig manure and of night soft. 5. Organic removal efficiency at room temperature (25$\circ$C) is 20-25% lower at medium temperature (35$\circ$C) in a same VS loading condition. 6. Refractory fraction of the infiuent VS and organic removal rate constant(K) estimated at around 37% and 0.107/day respectively.

• Asian-Australasian Journal of Animal Sciences
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• v.6 no.2
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• pp.319-323
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• 1993

The effect of bovine growth hormone digested with trypsin on whole-body protein synthesis in vitro of chicken embryos was investigated by using a whole-embryo culture system. Bovine growth hormone at 5.3 and 530 ng/ml was digested partially and completely with trypsin for 4 min and 18 h, respectively. After culturing chicken embryos with a synthetic medium containing $L-[4-^3H]$ pheylalanine, whole-embryo protein synthesis was determined from the ratio of specific radioactivities of free and protein-bound pheylalanine. Whole-embryo protein synthesis of the control group cultured with no bovine growth hormone was $49.5{\pm}2.2%/d$. There was no significant interaction between digestion time and the concentration of trypsin-digested bovine growth hormone. Tryptic digestion of bovine growth hormone increased fractional synthesis rates of whole-body protein compared to the 0-min groups, and there was no significant difference between the 4-min and 18-h groups. The higher concentration (530 ng/ml) of trypsin-digested bovine growth hormone was more effective in enhancing whole-embryo protein synthesis than the lower concentration (5.3 ng/ml).

• Korean Journal of Food Science and Technology
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• v.22 no.4
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• pp.466-472
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• 1990

The effect of sugar addition and heat treatment on the myofibrillar protein extractability was studied. Maillard reaction was dependent on heating time significantly and glucose revealed the highest reactivity for Maillard reaction. The extractability of myofibrillar proteins was lowest in case of glucose addition and decreased according to increasing of heating time, Higher extractability was resulted in by digestion of myofibrillar proteins with enzymes after sugar addition and heat treatment than the undigested samples, as the sample was digested with trypsin that is the highest. And by digestion with trypsin, chymotrypsin and peptidase at a time the extractability of meat proteins increased remarkably.

• KSBB Journal
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• v.6 no.2
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• pp.135-141
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• 1991

This study thus looks into two treatment processess : i) Anaerobic digester coupled with hollow fibre membrane unit. Treatment of starch waste with anaerobic digester-membrane system was studied. $0.17\m^2$ area of hollow fibre membrane unit of known pore size was immersed into laboratory-scale anaerobic digestion system. The pore size of membrane was varied from 0.03 to $\0.15mu$m. The hydraulic retention time of anaerobic digester was varied from 1.5 to 10 days. The effect of hydraulic retention time on treatment efficiency was significant while effect of membrane size was not significant. The gas production was about 0.74㎥/kg COD treated. The COD removal efficient was about 80-95% depending on the hydraulic retention time. ii ) Crossflow ultrafiltration as post treatment to anaerobic filter. The effluent from anaerobic filter, which had a total COD in the range of 4,500-5,200 mg/L was treated by crossflow ultrafiltration units. The study conducted with different membrane pore size indicated that membrace 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 $120-130 L/\m^2$.h. A study was conducted to see the long term clogging effect of membrane also.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.2
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• pp.53-63
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• 2018

The hydrolysis of organic solid waste, such as sludge, is the rate-limiting step of the anaerobic digestion. The longer rate-limiting step lead to decrease of treatment efficiency and increase hydraulic retention time and anaerobic digester. Therefore, the pre-treatment has been applied for accelerating the hydrolysis step. This study was investigated the effects of pre-treatment of waste activated sludge using ultrasonic and alkaline integrated treatment simultaneously. The results showed the cumulative methane production and the methane production rate increased while the lag phase decreased. Therefore ultrasonic and alkaline integrated pre-treatment of waste activated sludge resulted in acceleration of hydrolysis step in anaerobic digestion.