• Journal of Environmental Health Sciences
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• v.24 no.2
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• pp.57-67
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• 1998

The characteristics of anaerobic degradation of phenol were studied in a fluidized bed reactor using a granular activated carbon as media. Increasing the phenol loading rate with variation of feed concentration was considered as an experimental variable. In the present anaerobic fluidized-bed reactor, the removal efficiency of phenol and COD was maintained about 93-99% and 91-96%, respectively, up to 3.6 kg-phenol/$m^3\cdot d$ of the phenol loading rate, but it was abruptly decreased under 5.0 kg-phenol/$m^3\cdot d$. The volumetric production of biogas per removed phenol was decreased linearly between 0.80-1.27 m$^3$ gas/kg-phenol (0.35-0.56 m$^3$-gas/kg-COD), increasing the phenol loading rate, and the methane content of biogas was 55-60% as similar to that estimated theoretically up to 3.6 kg-phenol/$m^3\cdot d$. But the production rate and methane content of biogas were suddenly decreased at the loading rate of 5.0 kg-phenol/$m^3\cdot d$. Therefore, the anaerobically biodegradable phenol loading rate of the present reactor was 3.6 kg-phenol/$m^3\cdot$ d in order to accomplish over 90% of the removal efficiency.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1052-1057
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• 2005

Recently, the ozone treatment of wasting activated sludge has become one of the effective and feasible process for the sludge reduction. The objective of this study is to investigate the availability of ozonized wasting sludge on external carbon sources 13r phosphorus release. Experiment results showed that the ozone treatment of activated sludge could produce a large amount of VFA such as acetic acid and isobutyric acid. For example, 50.24 mg/L acetic acid was produced with the ozone dose of 0.05 g $O_3/g$ SS, and 123.56 mg/L acetic acid with 0.5 g $O_3/g$ SS. The higher ozone dose was applied, the more VFA was produced from sludge reduction into a limited point. Finally, using ozonated sludge as only carbon source, the batch experiment, to measure phosphorus release rate in anaerobic condition were performed. The specific phosphorus release rates were investigated as 0.94, 1.37, 1.48, 1.68 mg P/g VSS/hr with ozone dose of 0.05, 0.1, 0.2, 0.5 g $O_3/g$ SS, respectively. Considering the degree of mineralization, VFA production, phosphorus release rate, and economical aspect, the optimal ozone dose for sludge reduction and using carbon sources ranged from 0.05 to 0.1 g $O_3/g$ SS.

• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.3
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• pp.126-137
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• 2006

Behaviors of simple organic compound and granular sludge in an upflow anaerobic sludge blanket (UASB) reactor treating propionate at high ammonia nitrogen levels were investigated for 12 months. The UASB reactor achieved about 80% removal of chemical oxygen demand (COD) at ammonia nitrogen concentration up to 6000 mg-N/L. At higher concentration of ammonia nitrogen, the propionate in the effluent increased whereas the acetate was very low. At ammonia nitrogen concentration of 8000 mg-N/L, the volatile suspended solids (VSS) increased sharply due probably to the decrease of the content of extracellular polymer (ECP) although methane production was very low. The specific methanogenic activity (SMA) using formate, acetate, and propionate as substrate to granules decreased as ammonia nitrogen concentration increased. The ammonia nitrogen concentration $I^{50}$, causing 50% inhibition of SMA were 2666, 4778 and 5572 mg-N/L, respectively. The kinetic coefficients of ammonia inhibition using formate, acetate, and propionate as substrate were 3.279, 0.999 and 0.609, respectively. The SMA using formate was severely affected by ammonia nitrogen than those using acetate and propionate. This result indicated that the hydrogenotrophic methanogens was most affected by ammonia nitrogen. Granules were mainly composed of microcolonies of methanothrix-like bacteria resembling bamboo-shape, and several other microcolonies including propionate degrader with juxtapositioned syntrophic associations between the hydrogen-producing acetogens and hydrogen-consuming methanogens.

• Korean Journal of Ecology and Environment
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• v.37 no.4 s.109
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• pp.436-447
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• 2004

Wetland plants have evolved specialized adaptations to survive in the low-oxygen conditions associated with prolonged flooding. The development of internal gas space by means of aerenchyma is crucial for wetland plants to transport $O_2$ from the atmosphere into the roots and rhizome. The formation of tissue with high porosity depends on the species and environmental condition, which can control the depth of root penetration and the duration of root tolerance in the flooded sediments. The oxygen in the internal gas space of plants can be delivered from the atmosphere to the root and rhizome by both passive molecular diffusion and convective throughflow. The release of $O_2$ from the roots supplies oxygen demand for root respiration, microbial respiration, and chemical oxidation processes and stimulates aerobic decomposition of organic matter. Another essential mechanism of wetland plants is downward water movement across the root zone induced by water uptake. Natural and constructed wetlands sediments have low hydraulic conductivity due to the relatively fine particle sizes in the litter layer and, therefore, negligible water movement. Under such condition, the water uptake by wetland plants creates a water potential difference in the rhizosphere which acts as a driving force to draw water and dissolved solutes into the sediments. A large number of anatomical, morphological and physiological studies have been conducted to investigate the specialized adaptations of wetland plants that enable them to tolerate water saturated environment and to support their biochemical activities. Despite this, there is little knowledge regarding how the combined effects of wetland plants influence the biogeochemistry of wetland sediments. A further investigation of how the Presence of plants and their growth cycle affects the biogeochemistry of sediments will be of particular importance to understand the role of wetland in the ecological environment.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.4
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• pp.66-73
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• 2009

Temperature phase anaerobic co-digestion process was conducted with the one to one mixture of food wastewater with livestock wastewater, and the presence and the dynamics of various pathogenic microorganisms was analyzed. The mixture contained various enteric and pathogenic bacteria, such as Escherichia coli. Enterobacteriaceae, Coliform bacteria. Staphylococcus aureus, Salmonella, Shigella, Listeria, and Yeast. Anaerobic digestion has become stabilized around 21 days after the reaction started, showing about 80% to 90% of remarkable reduction rates of microorganisms until this period in acidogenic reactor (AR) and methanogenic reactor (MR), respect ively. After stabilization, the average reduction rate of organic matter was recorded as around 60% in MR. Most microorganisms in the effluent were not detected at around the last period of the reaction, except Listeria and S. aureus, which showed the growth even at the last day of the reaction.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.502-502
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• 2023

지난 140여년(1880~2022)간 지구의 연평균 기온은 약 1.5℃ 상승하였다. 이에 따라 폭염, 홍수, 가뭄 등 이상기후 발생이 급증하고 있으며, 생태계가 급격히 변화하여 담수호의 산소량 또한 급속히 감소하고 있다. 소양호는 총길이 60 km, 유역면적 2.703 km², 최대저수량 29억톤으로, 유역면적은 북한강 유역의 25%에 달하며 북한강 상류에 위치하고 있는 국내 최대의 인공호이다. 따라서 소양호 유역의 관리는 북한강 유역의 수질 관리와 수도권 수자원 공급의 핵심 중 하나라고 볼 수 있다. 그러나 기후변화에 따라 소양호의 성층현상에도 변동이 생겼을 것으로 판단되고 있다. 호소의 성층현상은 수심에 따른 온도의 변화로 발생하는 현상으로, 성층현상이 심하면 유체는 연직운동이 제한되고 상대적으로 수평방향 운동이 활발해진다. 소양호는 수심이 매우 깊으며, 열용량이 크기 때문에 여름에 성층이 형성되는 온대일순환호(warm monomictic lake)로 분리된다. 성층현상이 심하면 호소 하부의 저층에서는 용존산소가 거의 없어 혐기성 상태가 되고, 침전된 유기물이 혐기성 미생물에 의해 분해되기 때문에 수질은 크게 악화된다. 따라서 본 연구는 30년간의 소양호의 수온과 DO의 변동을 분석하여 성층현상의 변동성을 파악하고자 하였다. 이에 따라 약 30년간(1993년 1월~2022년 12월) 0~90 m까지 측정한 수온, DO 데이터를 이용하였다. 데이터는 매달 최소 1회~최대 5회 측정된 자료 중 가장 수심이 깊게 측정된 날의 자료를 이용하였다. 1월과 2월의 데이터는 동절기로 인해 소양호 조사를 실시할 수 없어 제외하였다. 수온의 경우 30년간 서서히 증가하는 경향을 보였으며 0~90m 전반에 걸쳐서도 대체로 증가하는 경향을 보였다. 또한 6월에 성층현상이 더 심해지고, 겨울에는 연직운동이 감소하는 모습을 보였다. DO의 경우 용존산소가 중층에서 최저를 보이는 Metalimnetic oxygen minimum을 보였으며, 2008년까지는 거의 매년 농도 2.0mg/L 이하인 달이 있었으나 그 이후에는 회복되어 대부분 2.0 mg/L 이상을 보였다. 그러나 심층의 경우에는 2014년부터 DO 농도 3 미만으로 떨어지는 경우가 증가하였다.

• Applied Chemistry for Engineering
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• v.3 no.4
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• pp.730-738
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• 1992

Filtration characteristics according to membrane materials were studied In the ultrafiltration of anaerobic digestion broth as a post treatment method. A series of resistances for different membranes were quantitatively assessed on the basis of the resistance-in-series model. Flux behavior observed with the digestion broth was irrelevant to initial water permeabilities of each membrane. The fluoro polymer membrane showed the most significant improvement of flux with increase of cross-flow velocity, which suggests that the cake layer formed on this membrane is more weakly attached to the membrane surface than those on the other membranes. Flux reduction during longtime running was attrib-used to the polarization layer resistance ($R_p$) as well as the fouling layer resistance($R_f$). Continuous increase of $R_p$ may reflect the variation in the characteristics of cake layers, which could result from size, shape, and structure changes due to lysis and growth of biomass. Hydrophilic cellulosic membrane had a much lower fouling tendency than hydrophobic polysulfone membrane. The depressurization method induced a small increase in flux of $5-10L/m^2/h$. During washing and cleaning, filtrability of each membrane was rapidly recovered within 15 minutes until a stationary value was reached.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.1
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• pp.31-40
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• 2016

In this study, mesophilic anaerobic digestion of source separated food waste was carried out by leachate recirculation system and methane gas was produced. Two systems - system A and B were fabricated and placed within water bath to maintain $36^{\circ}C$. Each system was comprised of an anaerobic bioreactor and a leachate tank. Leachate in bioreactor was separated through the screen located at 30 mm above the bottom and a pump was installed to transfer collected leachate to the leachate tank. Everyday, 2.5 L of the leachate was pumped from the bioreactor to the leachate tank for 30 min and transferred leachate was pumped back to the top of the bioreactor for 30min, sequentially. Source separated food waste used for this experiment was washed by water before transferring to the laboratory. Transferred food waste was warmed to $36^{\circ}C$ before being fed to bioreactors. System A was fed to 49.1 g VS (Volatile Solids) and System B was fed to 54.0 g VS at every two weeks, respectively. $NH_4{^+}-N$ and salinity were monitored to see the inhibition toward anaerobic bioreaction and it was found that concentrations of these materials were not high enough to affect the bioreaction. Although the food waste was fed biweekly for 112 days and 140 days at system A and B, respectively, there was no sludge withdrawal from each system. Average methane productions rates were 0.439 L $CH_4/g$ VS and 0.368 L $CH_4/g$ VS for system A and B, respectively.

• Korean Journal of Environmental Agriculture
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• v.23 no.4
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• pp.220-227
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• 2004

This study showed that thermophilic anaerobic acid fermentation of food wastes had an enhanced hydrolysis capability and improvement of acidification efficiency. Influence of pH on the anaerobic hydrolysis and acidogenesis was investigated to determine the proper alkalinity in the thermophilic fermentation of food wastes. The results of putting NaOH as alkali to evaluate hydrolysis and acid fermentation efficiency In acid fermentation process of food wastes showed that the food wastes pretreated with 0.05 g NaOH/g TS had the maximum 12,600 mg/L of VFAs concentration during HRT 3 days in $55^{\circ}C$ thermophilic condition and the maximum 9,700 mg/L of VFAs concentration during HRT 5 days in $35^{\circ}C$ mesophilic condition. The accomplishment of high VFAs concentration resulted from that the main component of food wastes such as cellulose, lignin and etc. is performed active chemical decomposition by alkali in thermophilic condition. The major components of VFAs produced from the thermophilic acid fermentation process of food wastes were the short chain fatty acids such as acetic acid, butyric acid, and propionic acid.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.207-210
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• 2004

Effect of electron accepters on anaerobic degradation of petroleum hydrocarbons by an anaerobic sludge taken from a sludge digestion tank in a soil artificially contaminated with 10,000 mg/kg soil of diesel fuel was tested. Treatments of soil with 30 mL of the digestion sludge (2,000 mg/L of vss (volatile suspended solids)) were incubated under several anaerobic conditions including nitrate reducing, sulfate reducing, methanogenic, and mixed electron accepters conditions for 120 days. Treatments with the digested sludge showed significant degradation of diesel fuel under all anaerobic conditions compare to control treatments with an autoclaved sludge and without the sludge. The amount of TPH degradation after 120days incubation was the largest in the treatment with the sludge and mixed electron accepters (75% removal of TPH) followed in order by sulfate reducing, nitrate reducing, methanegenic condition as 67%, 53％, 43%, respectively. However, the rate of TPH degradation in the nitrate- and sulfate reducing condition within 105 days were comparable with that of the mixed electron accepters condition. Microorganisms in each electron acceptor condition were plated on solid mediums containing nitrate or sulfate as sole electron acceptor and several nitrate- and sulfate reducing bacteria showed effective degradation of diesel fuel within 30 days incubations. These results suggest that anaerobic degradation of diesel fuel in soil with digested sludge is effective for practical remediation of soil contaminated with petroleum hydrocarbons.