• Environmental Engineering Research
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• v.25 no.1
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• pp.80-87
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• 2020

Landfill waste decomposition generates a dark effluent named, leachate which is characterized by high organic matter content. To minimize these polluting effects, it becomes necessary to develop an effective landfill leachate treatment process. The objective of this study was to evaluate the performance of an innovative approach based on air stripping, anaerobic digestion (AD) and aerobic activated sludge treatment. A reduction of 80% of ammonia and an increase of carbon to nitrogen ratio to 25 were obtained, which is a suitable ratio for AD. This latter AD was performed in fixed bed reactor with progressive loading rate that reached 2 and 3.2 g COD/L/d for the raw and diluted leachate (1:2), respectively. The anaerobic treatment led to significant removal of chemical oxygen demand (COD) and biogas production, especially for the diluted leachate. The COD removal was of 78% for the raw leachate and a biogas production of 4 L/d with 70% methane content. The use of the diluted leachate led to 81% of COD removal and 7 L/d biogas with 75% methane content. It allowed a removal of 77% COD and more than 97% of the organic compounds present in the initial leachate sample.

• Journal of Korean Society on Water Environment
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• v.21 no.1
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• pp.34-39
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• 2005

The performance of elutriated acid fermentation with slurry-type piggery waste was investigated, especially to evaluate the effects of temperature and pre-treatment. In the first phase, the acid elutriation reactor with piggery waste after centrifugation operated at both mesophilic and thermophilic conditions to evaluate the effect of temperature. Solubilization yield($gVFAs/gSCOD_{prod.}$) and acidification rate($gVFAs/gSCOD_{prod.}$) in the thermophilic digestion were 0.45 and 0.55, which were higher than those of the mesophilic digestion, 0.25 and 0.45. In addition, the acid elutriation reactor at thermophilic temperature is more effective in removing e-coli. In the second phase, the acid elutriation reactor was fed with piggery waste before centrifugation. With piggery wastes before centrifugation, the solubilization yield and the acidificaton rate were 0.40 and 0.80, respectively, which were higher than the rates using piggery waste after centrifugation at both mesophilic and thermophilic conditions. The higher sludge volume reduction of 80% benefits sludge management. Furthermore, economical advantages can be achieved by removing the pre-treatment process, such as centrifugation. Consequently, the treatment with piggery waste before centrifugation proved to be effective. Also, the optimum temperature condition was estimated at mesophilic or thermophilic conditions, considering solubilization yields and acidification rates, though the system should be heated.

• KSBB Journal
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• v.25 no.6
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• pp.547-552
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• 2010

The recent bloom of a very large jellyfish Nemopilema nomurai has caused a danger to sea fishery and sea bathers. Presently, Nemopilema nomurai is thrown away through a separator system in the sea. The objective of this work was to produce bio-gas from Nemopilema nomurai by using anaerobic digestion. The bio-gas includes the hydrogen or the methane gases. It relates that Nemopilema nomurai is effectually changed into the renewable energy. When the jellyfish biomass was used as an organic carbon source the bio-gases were evolved. The aim of this study was to determine the optimal conditions for hydrogen and methane gases production according to the substrate concentrations of Nemopilema nomurai, optimal culture condition and the sludge-pretreatment without pH control. The optimal culture condition was found to be $35^{\circ}C$ and the heat-treatments of jellyfish was done at $120^{\circ}C$ for 30 min. The production rate of hydrogen and methane gas were found to be 8.8 mL/L/h, 37.2 mL/L/h from 1.5 g of dry Nemopilema nomurai.

• Korean Journal of Environmental Agriculture
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• v.29 no.2
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• pp.197-205
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• 2010

This study was conducted to investigate the optimum conditions for efficient methane production through anaerobic digestion of pig waste slurry. The examined parameters were organic matter content of the pig slurry, the ratio of seed sludge to pig slurry, and stirring intensity of the digestion reactor. The effects of types of slurry produced from different purpose-based pigs fed with different feeds were also tested. The methane concentration in the produced biogas was 45% when the ratio of seed sludge to pig slurry was 50% and total solid (TS) concentration was 1%, and it increased in proportional to TS concentration increases from 3 to 7%. At 3 and 5% of TS concentration, increasing mixing velocity from 80 to 160 rpm resulted in higher biogas production amount. However, mixing amount of seed sludge did not cause any significant effect on biogas production. Overall, the most efficient biogas production was achieved at 3-5% TS concentration in combination with 50% seed sludge inoculation and mixing velocity at 120 rpm. Among pig slurry types, gestating sow waste slurry showed the highest biogas production probably due to higher the degradation rate than other types of pig waste slurry being affected by the feeds components.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.2
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• pp.93-101
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• 2000

The objective of this study was to evaluate the possibility of co-digestion of food waste and sewage sludge mixture using anaerobic system. The Biochemical methane Potentials of cabbage and food waste were $297ml\;CH_4/g$ VS and $306.7ml\;CH_4/g$ VS, respectively. The biodegradability of food waste was 60%. The concentrations of acetate, propionate, and isobutyrate produced during the aerobic acidogenesis of food waste for 36 hours were 7,000~7,200 ppm, 260~280 ppm, 380~400 ppm, and 40~50 ppm, respectively, of which acetate was over 85%. The concentrations of acetate, propionate, and isobutyrate produced during the anaerobic acidogenesis for 36 hours were 1,400~1,600 ppm, 30~40 ppm, 220~250 ppm, and 260~300 ppm, respectively, of which acetate was over 70%. The biodegradabilities of aerobic and anaerobic acidogenesis were 30% and 25%, respectively. Methanogensis could be activated under 1 % of NaCl and 1,000 ppm of volatile fatty acids at the range of pH 6.8~7.2. The maximum mixture ratio of food waste and sewage sludge in the present study was 2:8 by the result of VS removal rate and Methane production.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.6
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• pp.628-636
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• 2008

Anaerobic denitrification in a two phase anaerobic digestion(TPAD) process combined with biological nutrients removal (BNR) system was studied for a piggery wastewater treatment. Denitrification efficiency and the effects of the nitrified effluent on acidification was investigated by recycling the nitrified effluent to the acidogenic reactor. Recycle of the nitrified effluent to the acidogenic reactor enhanced the conversion efficiency of the influent COD into volatile fatty acids(VFAs) in the TPAD-BNR system treating the piggery wastewater. Acidification rate of the acidogenic sludge acclimated with the nitrified effluent showed 6 times higher than that acclimated without it. VFA could be used for denitrification as carbon sources, however, nitrate could enhance acidification activity in the acidogenic reactor. VFA production rate was affected on the COD/Nitrate(COD/N) ratio, however, it depended much more whether the acidogenic sludge acclimated with nitrate or not. Denitrification with the acidogenic sludge acclimated without nitrified effluent followed zero-order reaction and the reaction rate constants were in the range of 1.31$\sim$1.90 mg/L$\cdot$h. Denitrification reaction rate constants of the acidogenic sludge acclimated with nitrified effluent were 3.30 mg/L$\cdot$h that showed almost twice of them evaluated from the previous tests. The stoichiometric ratios of utilized COD to removed nitrate showed similar in both tests which were in the range of 5.1$\sim$6.4 at COD/N ratio of 10.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.6
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• pp.893-906
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• 2011

The effect of ultrasound pretreatment on sludge degragability was investigated at different condotions: ultrasonic frequency(28, 40, 50kHz), intensity(10, 25, 50W), sonication time(10, 20, 30, 60min). Total suspended solid(TSS) and soluble chemical oxygen demand(SCOD) concentration were measured for the evaluation of pretreatment efficiency. The pretreated sludge was used as the feedstock for anaerobic digestion process. Biogas production and volatile suspended solid(VSS) removal were determined for evaluating the process performance. 1. TSS concentration of the sludge decreased at a constant rate as sonication operation was applied. The degradation rate of TSS increased when ultrasound frequency was decreased from 50kHz to 28kHz and intensity was increased from 10W to 50W. Efficiency of TSS degradation per input energy increased as ultrasonic frequency and intensity were decreased. At the frequency of 28 and 40kHz, SCOD concentration rapidly increased during the initial 30min of sonication time, and then it gradually increased. At 50kHz, SCOD concentration constantly increased for 60min of the sonication time. The SCOD production rate increased with increasing intensity under all ultrasound frequencies. 2. The optimum condition of ultrasound treatment was 28kHz, 50W and 60min for maximizing the biogas production, methane fraction, VSS removal. The highest values in biogas production, methane fraction in biogas, VSS removal were 370ml, 70%, 2.45g, respectively. Methane production rate per input energy increased at ultrasonic frequency and intensity decreased. 3. When raw sludge was pretreated at the condition of ultrasonic frequency of 28 and 40kHz in series, sequential-frequency sonication, intensity of 50W and 60min, biogas production, methane fraction, VSS removal were about the same that of 28kHz single-frequency sonication. When sequential-frequency sonication of 28 and 50kHz was applied in series, biogas production, methane fraction, VSS removal were 356 ~ 423ml, 69 ~ 71%, 2.41 ~ 2.78g, respectively. The pretreatment efficiency of 28-50kHz sequential-frequency sonication which sonication time of 28kHz and 50kHz was 40min and 20min was higher than that of 28kHz single-frequency sonication.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.3
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• pp.104-110
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• 2001

In this study, the effect of physico-chemical variables on sludge conditioning was determined to enhance dewaterability of effluent produced from the thermophilic anaerobic digestion of food waste. The gas production rate and methane content during the anaerobic digestion of food waste were $1.1m^3/kg$ VS and 63%, respectively, and the biodegradability of volatile solids was 87.5%. The concentrations of CODcr, TKN and TP of effluent from digestor were 18,500mg/L, 2,800mg/L, and 582mg/L, respectively. At the jar test to screen the flocculant for the dewatering of effluent from digestor, $FeCl_3$ and strong cationic polymer were effective on making flocs in the effluent. The condition of flocculation of effluent were 500mg/L of $FeCl_3$ and 50-100 mg/L of strong cationic polymer, respectively. As the result of measuring of dewaterability potential of effluent to determine the mixing ratio between $FeCl_3$ and polymer by capillary suction time(SCT), optimum condition was 500mg/L of $FeCl_3$ and 80mg/L of strong cationic polymer.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.101-101
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• 2010

Anaerobic digestion(AD) is the most promising method for treating and recycling of different organic wastes, such as organic fraction of municipal solid waste, household wastes, animal manure, agro-industrial wastes, industrial organic wastes and sewage sludge. During AD, i.e. organic materials are decomposed by anaerobic forming bacteria and fina1ly converted to excellent fertilizer and biogas which is a mixture of carbon dioxide and methane. AD has been one of the leading technologies that can make a large contribution to produce renewable energy and to reduce $CO_2$ and other green-house gas(GHG) emission, it is becoming a key method for both waste treatment and recovery of a renewable fuel and other valuable co-products. Currently some 80% of the world's overall energy supply of about 400 EJ per year in derived from fossil fuels. Nevertheless roughly 10~15% of this demand is covered by biomass resources, making biomass by far the most important renewable energy source used to date. The representative biofuels produced from the biomass are bioethanol, biodiesel and biogas, and currently biogas plays a smaller than other biofuels but steadily growing role. Traditionally anaerobic digestion applied for different biowaste e.g. sewage sludge, manure, other organic wastes treatment and stabilization, biogas has become a well established energy resource. However, the biowaste are fairly limited in respect to the production and utilization as renewable source, but the plant biomass, the so called "energy crops" are used for more biogas production in EU countries and the investigation on the biomethane potential of different crops and plant materials have been carried out. In Korea, with steadily increasing oil prices and improved environmental regulations, since 2005 anaerobic digestion was again stimulated, especially on the biogasification of different biowastes and agro-industrial biomass including "energy crops". This study have been carried out to investigate anaerobic biodegradability by the biochemical methane potential(BMP) test of animal manures, different forage crops i.e. "energy crops", plant and industrial organic wastes in the condition of thermophilic temperature, The biodegradability of animal manure were 63.2% and 58.2% with $315m^3CH_4/tonVS$ of cattle slurry and $370m^3CH_4/tonVS$ of pig slurry in ultimate methane yields. Those of winter forage crops were the range 75% to 87% with ultimate methane yield of $378m^3CH_4/tonVS$ to $450m^3CH_4/tonVS$ and those of summer forage crops were the range 81% to 85% with ultimate methane yield of $392m^3CH_4/tonVS$ to $415m^3CH_4/tonVS$. The forge crops as "energy crops" could be used as good renewable energy source to increase methane production and to improve biodegradability in co-digestion with animal manure or only energy crop digestion.

• Korean Journal of Environmental Agriculture
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• v.23 no.1
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• pp.1-6
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• 2004

The seeding sources and concentration of ammonia on anaerobic digestion were investigated by batch culture bioreactors. The sources of seeding on anaerobic digestion were from swine wastewater collection pit of a hog raising farm and from anaerobic digestion sludge of a municipal sewage treatment plant. The inhibition of ammonia on anaerobic microorganisms was initiated at ammonia concentration of $1,500\;mgNH_4-N/L$ and it's effect was increased by increased by increasing ammonia concentration up to $3,500\;mgNH_4-N/L$ regardless the sources of seeding as evidenced by decreases in COD removal efficiencies and biogas yields. The inhibition occurred to not only methanogens but also acidogens since the concentration of volatile fatty acids was maintained at 50 mg/L The COD removal efficiency and biogas yield were Maintained constantly while increasing ammonia concentration up to $3,500\;mgNH_4-N/L$ when swine wastewater collection pit was used as a seeding; however, those were decreased while increasing ammonia concentration when anaerobic digestion sludge was used as a seeding. The results indicate that the seeding acclimated to high concentrations of ammonia for long time was easy in adaptation to high ammonia concentration and less subjective to ammonia inhibitory effects.