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황산과 암모니아를 이용한 목질계 바이오매스의 전처리 공정에 따른 당화 및 발효공정 전략
( Roent Dune Cayetano ),김태현 ( Tae Hyun Kim ),엄병환 ( Byung Hwan Um ) 한국화학공학회 2014 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.52 No.1
본 연구는 농업 부산물인 옥수수대(corn stover)를 이용하여 묽은 황산법(DSA; dilute sulfuric acid)과 암모니아 침지 법(SAA; soaking in aqueous ammonia) 그리고 암모니아 재순환 침출법(ARP; ammonia recycle percolation)을 비교하여 각 전처리법의 특징과 장단점을 분석하였고, 동시당화공동발효를 통한 에탄올 생산을 비교하였다. ARP, DSA, SAA를 이용하여 전처리된 고형물(3% 글루칸 투입)을 15 FPU/g-glucan, 30 CBU/g-glucan의 상업용 효소(Spezyme CP와 Novozyme 188;)와 E. coli KO11 균주(ATCC® 55124)를 이용하여 동시당화공동발효를 수행하였다. 전처리 후에 남은 고형물에 있는 당의 최대이론적 에탄올 수율은 각각 87, 90 그리고 78%였다. 이것은 전처리되지 않은 원래 옥수수대의 총 당량(글루칸 +자일란) 대비 각각 69, 58, 및 74%에 해당하는 것으로 SAA의 수율이 가장 높게 관찰되었다. 또한 전처리 당화액을 이용한 동시당화공동발효 실험결과는 DSA의 당화액이 발효균주에 대하여 가장 높은 독성을 나타내었고 ARP 전처리 당화액이 그 다음으로 저해효과가 큰 것으로 나타났다. 결국 SAA를 이용하여 전처리한후 리그닌 이 풍부한 당화액은 이용하지 않고 전처리된 고형물과 동시당화공동발효 공정을 이용한 에탄올 생산이 가장 간단하면 서 경제적인 공정으로 제안되었다. This is to study the effects of various pretreatment methods of agricultural residue, corn stover, and to compare the feature and pros and cons of each method including dilute sulfuric acid (DSA), soaking in aqueous ammonia (SAA), and ammonia recycle percolation (ARP). In order to convert corn stover to ethanol, various pretreatments followed by simultaneous saccharification and co-fermentation (SSCF) were tested and evaluated in terms of ethanol yield. With 3%, w/w of glucan loading using ARP-, DSA-, and SAA-treated solids, SSCFs using recombinant E. coli strain (ATCC® 55124) with commercial enzymes (15 FPU of Spezyme CP/g-glucan and 30 CBU/g-glucan enzyme loading) were tested. In the SSCF tests, 87, 90, and 78% of theoretical maximum ethanol yield were observed using ARP-, DSA-, and SAA-treated solids, respectively, which were 69, 58, and 74% on the basis of total carbohydrates (glucan + xylan) in the untreated corn stover. Ethanol yield of SAA-treated solid was higher than those of ARP- and DSA-treated solids. In addition, SSCF test using treated solids plus pretreated hydrolysate indicated that the DSA-treated hydrolysate showed the strongest inhibition effect on the KO11 strain, whereas the ARP-treated hydrolysate was found to have the second strongest inhibition effect. Bioconversion scheme using SAA pretreatment and SSCF can make the downstream process simple, which is suggested to produce ethanol economically because utilization of hemicellulose in the hydrolysate is not necessary.
( Roent Dune Cayetano ),( Tae Hyun Kim ) 한국폐기물자원순환학회(구 한국폐기물학회) 2015 한국폐기물자원순환학회 3RINCs초록집 Vol.2015 No.-
Corn stover was pretreated using anhydrous ammonia to improve enzymatic saccharification yield, termed as low moisture anhydrous ammonia (LMAA). LMAA method was previously developed in our laboratory in order to reduce water and chemical inputs. In this method, corn stover is moisturized to approximately 50% moisture content. Moisturized corn stover is then contacted with anhydrous ammonia (0.1g NH<sub>3</sub>/g-oven dry biomass) in a batch reactor under mild reaction conditions (~ambient conditions). After the moisturization and ammoniation stage, ammoniated biomass is subjected to the pretreatment at moderate temperatures (60-150℃) for 72-144 h. After pretreatment step, excess ammonia is evaporated and recovered without washing step. The pretreated biomass is hydrolyzed using cellulase enzyme into fermentable sugars. The highest glucan yield (85.3%) with 15 FPU (filter paper unit) of cellulase/g-glucan enzyme loading was observed at 90℃ for 120 h of pretreatment conditions. It was also observed that pretreatment at elevated temperature (130-150℃) disrupted hemicellulose (mostly xylan) significantly and increased reaction time also decreased hemicellulose contents. Moreover, lignin content of pretreated sample increased as reaction temperature increased. This phenomenon was found to result in inhibition effects on enzymatic saccharification of corn stover.
( Roent Dune A. Cayetano ),박종훈 ( Jong-hun Park ),김상현 ( Sang-hyoun Kim ) 한국폐기물자원순환학회(구 한국폐기물학회) 2018 한국폐기물자원순환학회 추계학술발표논문집 Vol.2018 No.-
This study evaluated the technical performance of the anaerobic treatment process of food waste in a lab -scale continuously stirred tank reactor attached to an external module containing a polyester support material with mesh pore size of 50 μm. Food waste was ground and sieved to achieve a uniform nominal size of 1-mm (16 US standard sieve scale) and diluted to approximately 50 g-COD/L. Hydraulic retention time (HRT) was varied from 40 to 10 days and was monitored alongside with the biogas production and effluent quality parameters. Dynamic membrane was successfully established on the polyester screen mesh. The highest average methane production rate and yield of 1.2 L-CH<sub>4</sub>/L/d and 0.34 L-CH<sub>4</sub> /g-COD were achieved at 10-d and 15-d HRT, respectively. The dynamic membrane provided a filter layer responsible for the reduction of suspended solids by 87%, which also explains the higher solids retention time than HRT. Moreover, implication of high methanogenic activity in the biofilm is attributed to the reduction of volatile fatty acid (87%) at the effluent. The qPCR technique also uncovered different amplification on the microbial templates of the samples. There was a consistent higher archaeal to bacterial population in the dynamic membrane layer compared to the suspended biomass in mixed liquor. This observation may explain why sufficient recirculation to the dynamic membrane bioreactor is essential for improved performance. Archaeal community was investigated using Illumina MiSeq sequencing, results showed it was mainly composed of Methanomicrobiales, methanosarcinales and methanomassiliicoccales in the order level. Methanolinea tarda under the order methanomicrobiales was the predominant species in dynamic membrane, which reached the highest relative abundance of 34.4% at 15-d HRT. Dynamic membrane would be useful for high-rate anaerobic digestion by providing better biomass retention in mixed liquor as well as acting as the active methanogenic biofilm layer.
Cayetano, Roent Dune A.,Kim, Tae Hyun Springer-Verlag 2017 Applied biochemistry and biotechnology Vol.181 No.4
<P>Corn stover was treated using low-moisture anhydrous ammonia (LMAA) at controlled ammoniation temperature. Moisturized corn stover (50 % moisture) was contacted with anhydrous ammonia (0.1 g NH3/g-biomass) in a batch reactor at various temperatures (ambient to 150 degrees C). After ammoniation at elevated and controlled temperature, ammoniated corn stover was pretreated at various temperatures (60-150 degrees C) for 72-144 h. Change in composition was marginal at low pretreatment temperature but was relatively severe with pretreatment at high temperature (130-150 degrees C). The latter resulted in low enzymatic digestibility. It was also observed that extreme levels (either high or low) of residual ammonia affected enzymatic digestibility, while residual ammonia improved by 1.0-1.5 %. The LMAA method enhanced enzymatic digestibility compared to untreated corn stover (29.8 %). The highest glucan and xylan digestibility (84.1 and 73.6 %, respectively) was obtained under the optimal LMAA conditions (i. e., ammoniation at 70 degrees C for 20 min, followed by pretreatment at 90 degrees C for 48 h).</P>
Food Waste Treatment in an Anaerobic Dynamic Membrane Bioreactor
( Roent Dune A. Cayetano ),( Jong-hun Park ),( Sang-hyoun Kim ) 한국폐기물자원순환학회(구 한국폐기물학회) 2019 ISSE 초록집 Vol.2019 No.-
An anaerobic dynamic membrane bioreactor using a woven polyester support material was previously established in treating food waste. The formation of the dynamic membrane layer was found to be beneficial to the stable performance of the anaerobic digestion system. In this study, shear velocity through the recirculation rate towards the dynamic membrane module was varied from 0.04 to 1.74 m/h. Food waste was prepared uniformly by grounding and sieving to a nominal size of 1-mm (16 US standard sieve scale) and was diluted to about 50 g-COD/L. Biogas production and effluent quality parameters were carefully monitored at varying shear velocities. Dynamic membrane was successfully established on the polyester screen mesh, however higher shear velocities of 1.74 m/h decreased the methane productivity by 24.5%. The highest average methane production rate and yield of 1.6 L-CH<sub>4</sub>/L/d and 0.33 L-CH<sub>4</sub>/g-COD were achieved at 0.34 m/h shear velocity.