• Biotechnology and Bioprocess Engineering:BBE
• /
• 제5권6호
• /
• pp.469-474
• /
• 2000

In order to enhance the degradation efficiency of waste activated sludge (WAS) by thermophilic aerobic digestion, an ultrasonic pretreatment was examined. It was observed that ultrasonic pretreatment increased the solubilization of organic matter in the WAS and that the solubilization ratio of the organics increased during the first 30 min but did not extensively increase thereafter. Therefore, a pretreatment time of 30 min was determined to be the economical pretreatment time from the experimental results. From the digestion experiments, which was conducted using the WAS collected from an oil refinery plant in Inchon, Korea, investigating the effects of an ultrasonic pretreatment on thermophilic aerobic digestion, it was confirmed that the proposed ultrasonic pretreatment was effective at enhancing the release of the cellular components in WAS and the degradation of released components in the thermophilic aerobic digestion.

• Journal of the Korean Wood Science and Technology
• /
• 제41권2호
• /
• pp.111-122
• /
• 2013

The steam explosion-chemical pretreatment is a more effective wood pretreatment technique than the conventional physical pretreatment by accelerating reactions during the pretreatment process. In this paper, two-stage pretreatment processes of hardwood were investigated for its enzymatic hydrolysis and the succinic acid yield from the pretreated solid. The first stage pretreatment was performed under conditions of low severity to optimize the amount of solid recovery. In the second stage pretreatment washed solid material from the first stage pretreatment step was impregnated again with chemical (alkaline or chlorine-based chemicals) to remove a portion of the lignin, and to make the cellulose more accessible to enzymatic attack. The effects of pretreatment were assessed by enzymatic hydrolysis and fermentation, after the two stage pretreatments. Maximum succinic acid yield (16.1 g $L^{-1}$ and 77.5%) was obtained when the two stage pretreatments were performed at steam explosion -3% KOH.

• Korean Chemical Engineering Research
• /
• 제61권3호
• /
• pp.412-418
• /
• 2023

The surge in the oil prices, increasing global population, climate change, and waste management problems are the major issues which have led to the development of biofuels from lignocellulosic wastes. Cellulosic or second generation (2G) bioethanol is produced from lignocellulosic biomass via pretreatment, hydrolysis, and fermentation. Pretreatment of lignocellulose is of considerable interest due to its influence on the technical, economic and environmental sustainability of cellulosic ethanol production. In this study, furniture waste sawdust was subjected to alkaline peroxide (H₂O₂) for the production of reducing sugars. Sawdust was pretreated at different concentrations from 1-3% H₂O₂ (v/v) loadings at a pH of 11.5 for a residence time of 15-240 min at 50, 75 and 90 ℃. Optimum pretreatment conditions, such as time of reaction, operating temperature, and concentration of H₂O₂, were varied and evaluated on the basis of the amount of total reducing sugars produced. It was found that the changes in the amount of lignin directly affected the yield of reducing sugars. A maximum of 50% reduction in the lignin composition was obtained, which yielded a maximum of 75.3% total reducing sugars yield and 3.76 g/L of glucose. At optimum pretreatment conditions of 2% H₂O₂ loading at 75 ℃ for 150 min, 3.46 g/L glucose concentration with a 69.26% total reducing sugars yield was obtained after 48 hr. of the hydrolysis process. Pretreatment resulted in lowering of crystallinity and distortion of the sawdust after the pretreatment, which was further confirmed by XRD and SEM results.

• Korean Chemical Engineering Research
• /
• 제56권4호
• /
• pp.441-446
• /
• 2018

초본계 바이오매스는 목본계 바이오매스에 비해 구조가 견고하지 않아 화학적 전환이 용이하다. 하지만 당질계 바이오매스에 비해 리그닌이 많아 전처리가 필수적으로 요구된다. 오르가노솔브는 리그닌과 같은 효소당화에 저해가 되는 물질을 분별하기 쉬우며 특히 에탄올과 같은 낮은 분자량의 용매는 증류를 통해 재사용이 용이하다는 장점이 있다. 한편 침출식 전처리 공정은 기존의 회분식 공정에서 문제점으로 언급되었던 분별된 성분들의 재결합 현상을 방지할 수 있고 고-액 분리가 용이하다는 장점이 있으며, 향후 스케일업에도 유리하다. 아직까지는 바이오알코올 생산 공정 중 전처리 과정에서 소모되는 에너지 비용이 크기 때문에 본 연구의 전처리에서는 촉매 없이 에탄올만을 이용해 부가공정의 발생을 줄이려고 했다. 침출식 전처리는 $150{\sim}190^{\circ}C$에서 30~99.5 wt% 에탄올을 이용하여 20~60분 동안 수행되었다. 높은 반응온도와 긴 반응시간은 에너지 소모가 크기 때문에 물리적 전처리 방법과의 연계를 적용하여 에너지 저감의 가능성을 알아보았다.

• Korean Chemical Engineering Research
• /
• 제54권4호
• /
• pp.448-452
• /
• 2016

새로운 수송용 에너지자원으로 각광받는 바이오매스의 효율적인 당화를 위한 전처리방법이 연구되고 있다. 최근 바이오매스의 에너지 전환 공정 중 전처리 비용이 높은 비중을 차지하고 있으며 이중 폐수처리가 커다란 문제점으로 지적되고 있다. 따라서 폐수발생을 줄이고 재사용이 용이한 유기용매(Organosolv)를 이용한 전처리를 수행하였으며, 전처리 바이오매스의 잔류 고형물의 양과 제거된 성분의 양을 이용하여 바이오매스의 전처리 효과를 효소당화를 통해 알아보았다. 전처리에 사용한 유기용매로는 99.5 wt% 에탄올을 사용하였고, 초본계 바이오매스인 옥수수대(corn stover)를 이용하여 전처리 하였다. 전처리 효과는 $130{\sim}190^{\circ}C$ 조건에서 시간대별로 진행하여 전처리된 바이오매스의 효소당화를 통하여 확인하였다. 효소당화결과로 가장 높은 글루코오스 당화율을 보였던 전처리 온도는 $190^{\circ}C$에서 반응시간 70분 이상의 조건 이였으며, 이 때 68% 이상의 당화율을 얻을 수 있었다. 또한 전처리 바이오매스의 잔류 고형물(Solid remaining)은 70% 이상이었고, 대부분의 셀룰로오스(Cellulose)와 헤미셀룰로오스(Hemicellulose)의 손실이 미비하여 대부분의 당 성분을 회수할 수 있다는 장점을 보였다.

• 한국염색가공학회지
• /
• 제17권6호
• /
• pp.20-26
• /
• 2005

For developing digital printing textiles, special pretreatment processes are necessary. These processes include developing formulation of coating agent and coating processes. The pretreatment were investigated with the variation concentration of anti-migration agent, fixation chemical etc.. The printing qualities according to pretreatment conditions were studied with color yield, printed capital letter sharpness and washing fastness. It was observed that the concentration of anti-migration agent, fixation agent(alkali) was closely related to printing qualities. For developing industrial technology of cellulosic digital printing textiles, optimum viscosity of pretreatment coating formulation is very important factor.

• Bulletin of the Korean Chemical Society
• /
• 제34권2호
• /
• pp.379-383
• /
• 2013

For the production of ethanol from freshwater cyanobacteria, a new pretreatment method using supercritical fluid was introduced. In this study, it was found that the supercritical fluid could penetrate inside the cell wall and help to liberate starch from cyanobacterial cells which resulted in the increase of the efficiency of ethanol production. For Microcystis aeruginosa, supercritical fluid pretreatment increased the amount of ethanol produced from cyanobacteria from 1.53 g/L to 2.66 g/L. For Anabaena variabilis, the amount of ethanol was increased from 1.25 g/L to 2.28 g/L. With use of supercritical fluid pretreatment, the efficiency of the process to obtain higher ethanol yields from freshwater cyanobacteria was improved upto 80%. The optimum temperature and pressure conditions for supercritical fluid pretreatment were determined as the temperature of $40^{\circ}C$ and the pressure of 120 atm. This study demonstrates the feasibility of using supercritical fluid pretreatment for ethanol production using freshwater cyanobacteria.

• Journal of Microbiology and Biotechnology
• /
• 제17권4호
• /
• pp.650-654
• /
• 2007

In our previous work, a method of pretreating lipase was developed to prevent loss of its activity during covalent immobilization. In this study, Rhizopus oryzae lipase was pretreated before immobilization and then immobilized on a silica gel surface. The effects of the various materials and conditions used in the pretreatment stage on the activity of immobilized lipase were investigated. Immobilized lipase pretreated with 0.1% of soybean oil had better activity than those pretreated with other materials. The optimal temperature, agitation speed, and pretreating time for lipase pretreatment were determined to be $40^{\circ}C$, 200rpm, and 45min, respectively. The activity of immobilized soybean oil pretreated lipase was 630U/g matrix, which is 20 times higher than that of immobilized non-pretreated lipase. In addition, immobilized lipase activity was maintained at levels exceeding 90% of its original activity after 10 reuses.

• Korean Journal of Chemical Engineering
• /
• 제35권11호
• /
• pp.2303-2312
• /
• 2018

Pretreatment process of silica-coated PET fabrics, a major low-grade PET waste, was developed using the reaction with NaOH solution. By destroying the structure of silica coating layer, impurities such as silica and pigment dyes could be removed. The removal of impurity was confirmed by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). The pretreated PET fabric samples were used for depolymerization into its monomer, bis(2-hydroxylethyl) terephthalate (BHET), by glycolysis with ethylene glycol (EG), and zinc acetate (ZnAc) catalyst. The quality of BHET was confirmed by DSC, TGA, HPLC and NMR analyses. The highest BHET yield of 89.23% was obtained from pretreated PET fabrics, while glycolysis with raw PET fabric yielded 85.43%. The BHET yield from untreated silica-coated PET fabrics was 60.39%. The pretreatment process enhances the monomer yield by the removal of impurity and also improves the quality of the monomer.

• Korean Chemical Engineering Research
• /
• 제52권4호
• /
• pp.430-435
• /
• 2014

섬유소계 바이오매스의 주요 구성요소 간의 관계에 의한 물리적, 화학적 장벽은 셀룰로오스를 발효 가능한 당으로 전환시키는 효소당화를 방해한다. 전처리의 주 목적은 셀룰로오스의 효소당화율을 향상시키기 위하여 기질로의 효소접근성을 높이는 것으로, 전처리 공정의 발전은 지속적으로 요구되고 있다. 본 연구에서는, 간단하고, 상대적으로 저비용인 암모니아수에 의한 침지공정을 전처리방법로 채택하였다. 기질로는 국내 농업 잔류물 중 생산량이 높은 볏짚을 채택하였다. 암모니아수에 의한 침지 공정은 3, 12, 24 그리고 72시간 동안 수행되었다. 그리고 동시당화발효에 미치는 전처리의 효과를 조사하기 위해, 효소당화와 동시당화발효를 30, 40 그리고 $50^{\circ}C$에서 수행하였다. 연구 결과에 따르면, 볏짚이 암모니아수에 의한 침지 처리 되었을 때, 기존의 보편적인 동시당화발효와 비교하여 상대적으로 적은 효소사용량과 낮은 온도($30^{\circ}C$) 조건에서도 당화와 동시당화발효가 수행될 수 있음을 확인하였다. 그리고 암모니아수에 의한 침지 처리는 초기 당화속도를 증가시킴으로써 24시간 이내에 발효를 종료시켰다.