• 멤브레인
• /
• 제23권2호
• /
• pp.101-111
• /
• 2013

나노 소재는 표면적이 매우 크고 크기나 기공이 균일하여 분리막에서 물질 전달 통로나 특수한 기능성을 갖게 하는 소재로 이용이 가능하다. 그러나 나노 소재 및 나노 기술을 기반으로 한 분리막의 상용화를 위한 여러 가지 기술적인 한계가 존재하며 최근 나노 소재 및 제조 기술이 발전하고 다양해짐에 따라 분리막에 나노 소재 및 기술을 활용하려는 연구가 많이 진행되고 있다. 나노 소재 및 기술을 활용하는 경우 기존 분리막의 투과도 및 선택도를 크게 높일 수 있으며 열적, 화학적, 기계적 안정성 및 내오염성을 향상시키거나 기능성 소재를 활용하여 분리막에 새로운 기능을 부여할 수 있다.

• 한국물환경학회지
• /
• 제30권5호
• /
• pp.486-490
• /
• 2014

Industrial use of microwave heating as an alternative to conventional heating is becoming popular mainly due to dramatic reductions in reaction time. Therefore, this work experimentally determined the effect of microwave irradiation on ammonia nitrogen removal in wastewater. The effects of air flow rate (0.3~0.9 L/min), treatment temperature ($70{\sim}100^{\circ}C$), and initial pH (9~11) were characterized. As the air flow rate increased from 0.3 to 0.9 L/min, the ammonia removal rate constant (k) increased from -0.6642 to $-1.0755min^{-1}$. As the temperature increased from 70 to $100^{\circ}C$, k increased -0.0338 to $-1.0755min^{-1}$. As the pH increased from 9 to 11, k increased -0.2443 to $-1.0755min^{-1}$. Ammonia removal was strongly dependent on temperature and pH rather than air flow rate. The results show that microwave irradiation is effective in ammonia nitrogen removal in wastewater due to advantages of fast and effective processing.

• 상하수도학회지
• /
• 제23권4호
• /
• pp.417-430
• /
• 2009

A BNR comprehensive performance evaluation (BNR CPE) system was established employing system-oriented evaluation methodology for biological nutrient removal (BNR) processes based on the CPE techniques developed by U.S. EPA for evaluation of conventional biological processes. The BNR CPE system applied to five domestic BNR plants adopting $A^2/O$ process confirmed that all target plants except the smallest one had not any serious defective performance and process stability was enhanced with increasing plant size. The system also clearly verified relatively poor performances in anoxic reactors without exception mainly due to influent carbon limit rather than functional defect. Consistent good performances were confirmed even during both winter season and wet weather generally known to be difficult to achieve satisfactory removals. Presentation of evaluation results by modified radar chart system simplified and clarified the evaluation and analysis procedures. The BNR CPE system could not only discover readily the causes of present and prospective poor performances but also facilitate the suggestion of their optimization options. Mutual effect and cause-and-effect among operation parameters and unit processes were also found easily using the evaluation system. The system justified that the adverse effect of defective operating parameters could be compensated by other favorable parameters, especially in anaerobic and anoxic reactors as well as during the winter season.

• 한국염색가공학회지
• /
• 제34권4호
• /
• pp.217-223
• /
• 2022

Flame-retardant finished silk fabrics could release carcinogenic formaldehyde resulting from the conventional finishing agents. New water-soluble cyclophosphazene derivative can be used as a formaldehyde-free flame retardant for the silk protein. Dichloro tetrakis{N-[3-dimethylamino)propyl]methacrylamido}cyclophosphazene(DCTDCP) can be cured by heat or UV irradiation as a durable flame retardant for the silk fabrics. Treatment conditions were optimized including curing temperature and time, finishing formulations, and UV energy. At the 30% DCTDCP application, peak HRR and THR decreased by 42.6% and 49.6% respectively compared to the pristine silk fabrics. Also char residue increased up to 48% from 11% indicating solid-phase retarding mechanism. The flame-retardant silk fabrics showed a LOI of 31.1 and the washed sample maintained a LOI of 26.8 even after ten laundering cycles.

• 한국축산식품학회지
• /
• 제22권3호
• /
• pp.222-227
• /
• 2002

진공포장한 한우육 우둔부위를 1$^{\circ}C$, 4$^{\circ}C$의 일반공기순환 냉장고와 1$^{\circ}C$, 4$^{\circ}C$의 냉수에 침지하여 3, 7, 10, 14일 동안 저장하였을 때, 처리구간의 물리적 육색 (CIE L*, a*, b*)은 크게 변화하지 않은 것으로 나타났다. 그러나 육색소 산화를 나타내는 MetMb의 함량은 처리구간에 따라 변화를 보여 대조구 (4$^{\circ}C$-공기순화)가 가장 빠른 증가를 나타내었으며, 저장 14일째 T2 (4$^{\circ}C$-냉수침지)구가 유의적으로 (p<0.05) 낮은 MetMb함량을 보였다. 한편 이런 결과는 지방산화와도 유사한 경향을 보였는데, 대조구 (4$^{\circ}C$-공기순환)의 TBARS 수치가 저장기간 동안 가장 빠른 증가를 나타낸 반면, T3(1$^{\circ}C$-냉수침지) 구의 TBARS는 크게 증가하지 않았다. 이러한 결과는 냉수침지 방법이 지방산화와 육색소 산화를 억제시킬 수 있다는 것을 의미한다. 포장감량 또는 공기순환 처리구(control, T1)가 냉수침지 처리구(T2, T3)에 비해 높게 나타났다. 총 육색소 함량은 전 저장기간 동안 처리구간에 유의적(p>0.05)인 차이가 없었다. 이상의 결과를 종합해 볼 때, 한우육을 진공포장하여 1$^{\circ}C$ 냉수에 침지시켜 숙성시키는 방법이 지방산화를 억제시키고 육색소의 안전성을 유지할 뿐만 아니라 포장감량도 줄일 수 있는 숙성법이라고 사료된다.

• 한국작물학회지
• /
• 제53권4호
• /
• pp.382-387
• /
• 2008

본 시험은 어린모, 중묘 등 묘령에 따른 쌀겨 시용 시기가 친환경 재배에 있어서 제초 효과와 벼의 수량 및 수량구성요소 그리고 더 나아가 미질에 미치는 영향을 구명코자 실시하였다. 1. 쌀겨 처리후 토양내 산화환원 전위차는 급격히 떨어져 심한 환원 상태로 변하였으며, 쌀겨 시용구에서는 쌀겨 살포 직후 $1{\sim}2$일 사이에 용존산소량이 급격히 줄어드는 경향을 보였다. 2. 쌀겨 시용구 중에서는 이앙전 5일 시용에서 잡초 본수 및 잡초 건물중이 가장 적거나 가벼워 잡초 발생이 상당히 억제되었으며, 이앙 후 늦게 살포할수록 잡초 발생량은 늘어났다. 3. 쌀겨 처리시기에 따른 수량은 이앙전 5일 시용에서 관행시비와 수량이 비슷하였으나, 이앙후 표면처리에서는 수량이 현저히 감수되었다. 4. 쌀겨 시용 시기에 따른 처리별 완전미 비율은 쌀겨 처리구에서 관행재배에 비해 높았고, 단백질 함량은 쌀겨 처리구에서 대체로 낮았다. 식미치는 완전미 비율이 높았고, 단백질 함량이 낮았던 쌀겨 시용구에서 관행재배에 비해 $2{\sim}8$ 정도 높았다.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2000년도 춘계학술발표대회
• /
• pp.89-91
• /
• 2000

Polynuclear aromatic hydrocarbon (PAH) compounds are highly carcinogenic chemicals and common groundwater contaminants that are observed to persist in soils. The adherence and slow release of PAHs in soil is an obstacle to remediation and complicates the assessment of cleanup standards and risks. Biological degradation of PAHs in soil has been an area of active research because biological treatment may be less costly than conventional pumping technologies or excavation and thermal treatment. Biological degradation also offers the advantage to transform PAHs into non-toxic products such as biomass and carbon dioxide. Ample evidence exists for aerobic biodegradation of PAHs and many bacteria capable of degrading PAHs have been isolated and characterized. However, the microbial degradation of PAHs in sediments is impaired due to the anaerobic conditions that result from the typically high oxygen demand of the organic material present in the soil, the low solubility of oxygen in water, and the slow mass transfer of oxygen from overlying water to the soil environment. For these reasons, anaerobic microbial degradation technologies could help alleviate sediment PAH contamination and offer significant advantages for cost-efficient in-situ treatment. But very little is known about the potential for anaerobic degradation of PAHs in field soils. The objectives of this research were to assess: (1) the potential for biodegradation of PAH in field aged soils under denitrification conditions, (2) to assess the potential for biodegradation of naphthalene in soil microcosms under denitrifying conditions, and (3) to assess for the existence of microorganisms in field sediments capable of degrading naphthalene via denitrification. Two kinds of soils were used in this research: Harbor Point sediment (HPS-2) and Milwaukee Harbor sediment (MHS). Results presented in this seminar indicate possible degradation of PAHs in soil under denitrifying conditions. During the two months of anaerobic degradation, total PAH removal was modest probably due to both the low availability of the PAHs and competition with other more easily degradable sources of carbon in the sediments. For both Harbor Point sediment (HPS-2) and Milwaukee Harbor sediment (MHS), PAH reduction was confined to 3- and 4-ring PAHs. Comparing PAH reductions during two months of aerobic and anaerobic biotreatment of MHS, it was found that extent of PAHreduction for anaerobic treatment was compatible with that for aerobic treatment. Interestingly, removal of PAHs from sediment particle classes (by size and density) followed similar trends for aerobic and anaerobic treatment of MHS. The majority of the PAHs removed during biotreatment came from the clay/silt fraction. In an earlier study it was shown that PAHs associated with the clay/silt fraction in MHS were more available than PAHs associated with coal-derived fraction. Therefore, although total PAH reductions were small, the removal of PAHs from the more easily available sediment fraction (clay/silt) may result in a significant environmental benefit owing to a reduction in total PAH bioavailability. By using naphthalene as a model PAH compound, biodegradation of naphthalene under denitrifying condition was assessed in microcosms containing MHS. Naphthalene spiked into MHS was degraded below detection limit within 20 days with the accompanying reduction of nitrate. With repeated addition of naphthalene and nitrate, naphthalene degradation under nitrate reducing conditions was stable over one month. Nitrite, one of the intermediates of denitrification was detected during the incubation. Also the denitrification activity of the enrichment culture from MHS slurries was verified by monitoring the production of nitrogen gas in solid fluorescence denitrification medium. Microorganisms capable of degrading naphthalene via denitrification were isolated from this enrichment culture.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
• /
• pp.42-45
• /
• 2006

A new and reusable energy source is water-treatment sludges. There is a significant need for understanding the characteristics of sludge combustion related to improving efficiency and ensuring the safety of this new energy source. Because sludges are composed of solids and gas mixture, the combustion of the mixture may become quite complex. Not only decomposition of conventional organic elements but also dust explosion may be important during the process of converting sludges into a new and safe form of energy. Sludge combustion mainly involves hydrogen, methane, hydro carbons, carbon, and organic particles. Dust explosion during the gasification stage may depend on the surrounding temperature and the composition of gases. The uncertainty in the explosive behavior of energetic source is noted in this work. We study the explosion characteristics of sludge combustion while the reusability of sewage sludges as a new form of energy is also investigated.

• 세라미스트
• /
• 제14권2호
• /
• pp.7-14
• /
• 2011

This paper has investigated physicochemical properties and conventional and environmental-friendly treatment methods of paper mill sludge to emphasize the importance and necessity of the sludge recycling. The paper mill sludge generally shows high contents of calcium and water, and is mostly discharged by landfill after incineration process rather than being recycled due to technical or economical problems. In recent years, however, several possible methods for recycling the paper mill sludge have been suggested for its sustainable process as follows; compost, raw material for the construction and paper industry, new energy source for reducing fossil fuel use and raw material of activated carbon for treating paper mill wastewater. Thus the authors suggest that practical recycling technologies of the paper mill sludge must be developed for substantiality in the paper industry through comprehending physicochemical compositions and generation status of the sludge and actively performing various related studies. Furthermore, this investigation could be used as preliminary information for the study on recycled paper development using paper mill sludge incineration ash.

• 펄프종이기술
• /
• 제43권5호
• /
• pp.34-42
• /
• 2011

A fiber processing method, which might be an alternative for conventional refining process, was introduced. The method consists of repetitive, gentle, mechanical impacts on fibers, followed by fiber uncurling process. This method was very effective for OCC and BCTMP for increasing WRVs (water retention value) while keeping fiber lengths from shortening. For OCC and BCTMP, gentle mechanical impacts on fibers using Hobart mixer increased breaking lengths and tear strengths simultaneously at fast drainage level, and straightening fibers using kady mill increased those strength properties further. For SwBKP and HwBKP, only mechanical impacts using the Hobart mixer were effective on increasing tensile and tear strength at fast drainage, but there were no further increase by kady mill treatment. The strength increases of BCTMP by this alternative fiber processing method were exceptionally high. An extensive engineering development should be followed to actualize this fiber processing mechanism in an energy-effect way.