• 한국환경보건학회지
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• 제23권1호
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• pp.95-104
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• 1997

The objectives of this study are to investigate the effect of media on the removal efficiency of nitrate-nitrogen and the biofilm thickness in the fluidized bed biofilm reactor(FBBR) used for the high rate denitrification of nitric acid wastewater. Granular activated carbon(GAC) of 1.274 mm diameter and sand of 0.455 mm diameter were used as the media in the FBBR of 0.05 m diameter and 1.5 m height. As the nitrate-nitrogen concentration of the influent was increased stepwise from 600 to 4800 mg/l, the nitrate- and nitrite-nitrogen concentration of the effluent, biofilm thickness and biofilm dry density were measured to study the effects of media on the denitrification efficiency. The biofilm thickness increased with the substrate loading rate, and the biofilm dry density decreased with the increase of the biofilm thickness. At the influent nitrate-nitrogen concentration of 2400 mg/l, the removal efficiency in the FBBR with GAC was 88%, while that in the FBBR with sand was 99.6%. The biofilm in the FBBR with GAC was so thick, 754.9 $\mu$m, as to increase the mass transfer resistance, compared to that, 143.7 $\mu$m, in the FBBR with sand. The maximum specific denitrification rate in the FBBR with GAC was 15.0 kg-N/m$^3\cdot$ day, while that in the FBBR with sand was 18.0 kg-N/m$^3\cdot$ day. The biomass concentration in the FBBR with sand exhibited the high value 37 kg/m$^3$.

• 한국수소및신에너지학회논문집
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• 제25권5호
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• pp.459-467
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• 2014

The catalytic steam reforming of toluene, a major component of biomass tar, was studied using several catalysts at various temperatures $400-800^{\circ}C$, kind of metal, and metal loading content. Ru and K promoted Ni-base catalyst were prepared, and used for steam reforming of toluene with steam/toluene molar ratio of 25. Concentration of toluene in reactant flow is $30g/Nm^3$ that is usual content of tar from biomass gasifier. The result from experiments showed that $H_2$ content in product gas and toluene conversion increased with temperature. Where in high temperature range, CO and $CO_2$ content in product gas were affected mainly by Boudouard reaction. Ni/Ru-K(3wt%)/$Al_2O_3$ catalyst showed best performance on steam reforming of toluene than used catalysts in this study at whole temperature. Catalysts have been characterized by XRD, TG. XRD analysis displayed that Ni particle size on Ni/Ru-K (3wt%)/$Al_2O_3$ catalyst was 29.4nm. Activation energy of Ni/Ru-K (3wt%)/$Al_2O_3$ catalyst was calculated 36.8kJ/mol by Arrhenius plot.

• 환경위생공학
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• 제10권1호
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• pp.45-65
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• 1995

Seasonal occurrences and dynamics on the freshwater algae were examined in the upstream of the Yongsan river system with the Kwangju service water area from 1993 to 1994. Three hundred and three taxi were totally collected and composed of 6 classes, 15 orders, 7 suborders, 31 families, 74 genera, 248 species, 48 varieties and 7 forma. Compositions in each algal class were divided in 136 taxi of Chlorophyceae(44.8% ), 109 taxi of Bacillariophyceae(36.0% ), 30 taxa of Cyanophyceae(10.1% ), 21 taxa of Euglenophyceae(6. 9% ),4 taxi of Chrysophyceae(1.3% ) and 3 taxa of Dinophyceae(1.0% ). The occurrence of taxa was a markedly decrease(-62) between summer and autumn, the critically increase(+43) between spring and summer. And also, it was indicated that the high frequency of taxa in summer, but the high standing biomass In winter in spite of low taxi. In general, it has much algal biomass in station 9 and 10, but low in station 4, 5 and 11, relatively. Through this survey, the major dominant taxa in algal biomass, Microcystis aeruginosa, Melosira varians, Synedra ulna and Navicula cryptocephala, they were all above 2.1×10$^{6}$ce11s/1, 13.2% of totals. There are about 10% of new emigrated taxa by season and they showed a remarkable succession. We may suggested that this system was well sustained for the habitat of freshwater algal community with low dominance and high diversity. Twenty three of nuisance algae including of Microcystis aeruginosa, Peridinium willei and Anabaena flos-aquae were distributed as if had low appearance. Of course, many of them were saprobiontic taxa, extraordinary growttung groups depend on organic loading in water system and also it was not showed severe algal blooming phenomenon.

• 상하수도학회지
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• 제14권1호
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• pp.37-44
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• 2000

Laboratory experiments were conducted to investigate the performances of anaerobic filters packed with ceramic tube and pall-ring media treating a dairy waste. The media packing volume was 65% of effective volume of anaerobic filter. Organics removals of anaerobic filters were maintained above 80% even at an organics loading rate of $10kgCOD/m^3/d$, and this was comparable to aerobic treatment of organic wastes. Organics removals of the ceramic tube anaerobic filters were always lower than those of the pall-ring anaerobic filters due to intrinsic physical property of ceramic tube, especially lower void space which caused to clogging and entrapment of biogas, substrate transfer limitation, and irregular evolution of biogas leading to loss of solids and biomass. This was clearly observed in higher concentration of TSS in the effluent from the ceramic tube anaerobic filter despite of higher retention capacity of TSS compared with pall-ring media. Vertical distribution of organics and solids in the filters showed above 90% of organics and solids in influent were removed below 20% of reactor height, and 50% of remaining organics and solids were removed though media packing zone. Effluent quality from the anaerobic filter was heavily depended on media itself as well as suspended biomass formed below media. It is therefore concluded that the type of media played an important role in biomass accumulation arid gas-liquid-solid separation efficiency. Type of media did not affect the start-up behaviors of the anaerobic filter, and supernatant from anaerobic digested sludge showed a good performance as a seeding materials.

• 한국지리정보학회지
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• 제15권1호
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• pp.184-196
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• 2012

바이오매스 연소 활동은 인위적 또는 자연적인 원인에 의하여 발생하며 연소과정에서 다량의 대기오염물질을 배출한다. 이 과정에서 발생한 온실가스와 대기 에어러솔은 대기환경 저해와 기후변화의 원인으로 알려져 있으나 바이오매스 연소 활동에 대한 감시와 대기환경에 미치는 영향을 파악하기가 쉽지 않다. 본 연구는 동북아 지역의 바이오매스 연소 활동의 현황과 대기환경에 미치는 영향을 평가하고자, 지구관측 위성인 Terra/MODIS 관측 자료를 이용하였다. 바이오매스 연소의 발생 원인은 매우 다양하지만, 주 연료가 공급되는 토지피복과 계절별 변화에 의존하므로, 본 연구에서는 지역별 토지피복과의 관련성과 시간에 따른 현황과 변화 패턴을 분석하였다. 그 결과, 가장 넓은 영역을 차지하고 있는 녹지대 또는 상록수림 지역에서의 발생수가 많았으며, 경작지에도 많은 발생횟수를 나타내었다. 그리고 대기 오염물질 중 하나인 대기 에어러솔의 상대적인 양을 나타내는 에어러솔 광학두께자료와 연소 자료와 비교결과는 두 산출물간 뚜렷한 연중 변화와 관련성이 있는 것으로 나타났다. 즉, 바이오매스 연소 활동이 지역 대기환경에 미치는 영향을 증명하였으며, 중국대륙에서 발생빈도가 증가하고 있어 지역 대기환경 및 기후변화에 영향을 줄 것으로 예상된다.

• Korean Chemical Engineering Research
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• 제49권4호
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• pp.470-474
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• 2011

볏짚은 한국에서 매년 대량 생산되는 주요 작물이다. 침지공정을 이용한 목질계 바이오매스의 전처리는 대기압과 $60^{\circ}C$의 온도에서 온화한 조건에서 수행되었다. 본 연구에서는 전처리된 바이오매스의 효소당화 조건을 찾아보았다. 볏짚의 경우에 이전의 목질계 바이오매스와 비교하여 당화시간이 다른 것들보다 짧은 것으로 나타났다. SAA(Soaking in Aqueous Ammonia) 전처리 볏짚의 당화는 40~48시간 사이에 종료가 되었고 $50^{\circ}C$에서 높은 글루코스 전환율을 나타냈다. 글루코스 전환율은 효소사용량이 각각 65 FPU/ml과 32 CbU/ml일 때 높았다. 기질 농도가 5%(w/v)일 때 전환율은 72시간 동안 당화 후에 83.8%로 나타났다. SAA 전처리 볏짚의 동시당화발효(SSF; Simultaneous Saccharification and Fermentation) 실험에서는 $40^{\circ}C$에서 높은 에탄올 생산수율을 보였다. 그때의 수율은 48시간에서 33.05%로 나타났다.

• 환경위생공학
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• 제8권1호
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• pp.107-116
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• 1993

This study is conducted to investigate treatability by activated sludge process for wastewater from acetaldehyde manufacturing plant. The optimum hydraulic retention time in aeration tank for removal of high strength substrate were measured. The removal efficiency were checked out by hydraulic retention time : 35hr., 40hr. and 45hr., respectively. $COD_{Cr}$, like substances were removed in all hydraulic retention time zone directed for efficiency, but non-biodegradable substances were remained. $COD_{Cr}$ biomass loading was 0.81kg $COD_{Cr}/kgMLVSS$ . day at 35hr. of retention time, 0.34 kg$COD_{Cr}$/kg MLVSS . day at 40hr., and O.l9kg$COD_Cr$/kgMLVSS . day at 45hr. And the mean $COD_{Cr}$, removal efficiency was 65.5%, 81.6% and 83.0%, respectively. And also $COD_{Cr}$, volume loading was 1.01kg$COD_{Cr}/m^3$ day, 0.87kg$COD_{Cr}/m^3$ - day, and 0.79kg$COD_{Cr}/m^3{\cdot }$day, respectively. The basic design parameter obtained is as fallows. The value of Specific substrate removal rate coefficient (k), Yield coefficient(Y) and Decay coefficient($k_d$) was $0.0013day^{-1}$, $0.505kgMLVSS/kgCOD_{Cr}$ and $0.040day^{-1}$, respectively.

• KSBB Journal
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• 제7권3호
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• pp.235-245
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• 1992

비표면적이 다른 media를 이용한 호기성 고정생물막공법에서 유기물부하율을 변화시키면서, 유출수의 성상과 활성슬러지의 설계인자가 호기성 고정생물막송법에 적용가능한지를 조사하였다. 유출수의 수질은 낮은 유기물부하율에서는 유출수의 농도가 비표면적에 따라 크게 변화하지 않았으나, 높은 부하율에서는 변화폭이 매우 크게 나타나으며, 비표면적별 유출수 농도를 보면 비표면적이 큰 경우가 유출수 농도가 낮았으며, 유입수농도가 클수록 유출수의 농도차이도 더 크게 나타났다. 동력학적 계수를 산출하기 위해 활성슬러지 공법의 모델을 고정생물막 공법에 적용시켜 본 결과 실험조건에서 실측 미생물 생산량과 계산된 미생물 생산량과의 차이는 COD를 기준으로 하였을 때가 더 잘 일치함을 알았다.

• 한국물환경학회지
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• 제18권2호
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• pp.113-122
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• 2002

A bench-scale anoxic membrane bioreactor (MBR) system, consisting of a bioreactor coupled to a ceramic crossflow ultrafiltration module, was evaluated to treat a synthetic wastewater containing alkaline hydrolysis byproducts (hydrolysates) of RDX, The wastewater was formulated the same as RDX hydrolysates, and consisted of acetate, formate, formaldehyde as carbon sources and nitrite, nitrate as electron accepters. The MBR system removed 80 to 90% of these carbon sources, and approximately 90% of the stoichiometric amount of nitrate, 60% of nitrite. The reactor was also operated over a range of transmembrane pressures, temperatures, suspended solids concentration, and organic loading rate in order to maximize treatment efficiency and permeate flux. Increasing transmembrane pressure and temperature did not improve membrane flux significantly. Increasing biomass concentration in the bioreactor decreased the permeate flux significantly. The maximum volumetric organic loading rate was $0.72kg\;COD/m^3/day$, and the maximum F/M ratio was 0.50 kg N/kg MLSS/day and 1.82 kg COD/kg MLSS/day. Membrane permeate was clear and essentially free of bacteria, as indicated by heterotrophic plate count. Permeate flux ranged between 0.15 and $2.0m^3/m^2/day$ and was maintained by routine backwashing every 3 to 4 day. Backwashing with 2% NaOCl solution every fourth or fifth backwashing cycle was able to restore membrane flux to its original value.

• 대한토목학회논문집
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• 제10권1호
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• pp.173-184
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• 1990

본 연구는 회전원판법에 의한 페놀성폐수의 처리시 최적유지물부하율과 적정유입페놀농도의 범위를 구하기 위하여, 유입페놀농도와 유기물부하율이 페놀과 유기물의 제거 및 미생물에 미치는 영향을 비교분석한 것으로, 페놀농도의 단계적 변화후 정상상태에서 SCOD와 페놀의 농도 및 미생물량을 측정하였다. 그 결과, 유업페놀농도 50.0~314.5 mg/L에서는 페놀의 제거효율이 98% 이상이었으나 401.5 mg/L에서는 그 효율이 71.5%로 감소하였다. 유기물제거율은 유입페놀농도가 증가함에 따라 감소하는 경향 보였으며, 페놀의 기질저해작용이 확인된 유입페놀농도 186.6 mg/L 이상의 범위에서 SCOD의 제거는 1차반응으로 나타났다. 또한 부착 미생물의 특성은 유입페놀농도에 따라 변화하였으며, 유입페놀농도 98.8 mg/L 이하에서는 filamentous growth 구조의 두꺼운 생물막이 발달하였고 314.5 mg/L 이상에서는 nonfilamentous growth 구조의 얇은 생물막이 발달되었다.