• Journal of Korean Society on Water Environment
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• v.35 no.4
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• pp.362-369
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• 2019

In this study, biodegradation efficiency improvement of mixed sludge for the anaerobic digestion process in wastewater treatment plant was investigated. In order to release the organic material contained in the sludge cell and promote the hydrolysis step, mixed sludge of 7% TS (Total Solids) was physically shear-treated at a shear strength of 1,000 ~ 4,000 rpm and a maximum of 120 mins. As a result of the comparison between mixed sludge before and after the treatment, the concentration of $SCOD_{Cr}$(Soluble Chemical Oxygen Demand-chromium method) was increased through the conversion of granular organic matter into dissolved organic matter as shear strength and treatment time increases. The solubilization efficiency increased rapidly after 30 min of solubilization application time, and they were 11.23 %, 20.10 %, 22.52 % and 25.43% at 120 min for each shear strength conditions, respectively. Additionally, the BMP(Biochemical Methane Potential) test was conducted with the optimized samples to determine the increase of methane production by the shear pre-treatment. Consequently, methane production of each samples were 0.275, 0.310, 0.323 and $0.335m^3/kg\;VS_{add}$, which indicates that methane production was increased to a maximum of 21.28% compared to the control without the solubilization process ($0.262m^3/kg\;VS_{add}$). As a result, the physical shear-treatment is a promising process for sewage sludge pre-treatment to reduce the organic waste and increase the energy production.

• Korean Journal of Environmental Agriculture
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• v.19 no.3
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• pp.194-200
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• 2000

The amount of swine wastewater reaches about $197,000m^3$ per day at live-stock houses in the whole country. A half of the swine wastewater resources are too small to be restricted legally. This untreated wastewater causes the eutrophication in the water bodies. In case of swine wastewater treatment, the solid-liquid separation must be performed because feces(solid phase) and urine(liquid phase) have large differences in nitrogen and phosphorus concentration. It is necessary to assess exactly the concentration of the pollutants in swine wastewater for planning the wastewater treatment facilities. A full-scale operation was carried out in K city and the plant is consists of conventional plant, the supplementary flocculation basin of chemical treatment process and $anaerobic{\cdot}aerobic$ basin for nitrogen removal. The improved full-scale swine wastewater treatment plant removed the $1,500{\sim}3,000mg/l$ of total-nitrogen(T-N) to 120mg/l of T-N and $131{\sim}156mg/l$ of total-phosphorus(T-P) to $0.15{\sim}1.00mg/l$ of T-N. Accordingly, as a results of operational improvement, the removal efficiencies of T-N and T-P were over $92{\sim}96%$, 99%, respectively. The continuous supply of organic carbon sources and the state of pH played important roles for the harmonious metabolism in anaerobic basin and the pH value of anaerobic basin maintained at about 9.0 for the period of the study.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.4
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• pp.508-517
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• 2020

This study aimed to determine the minimum period of aeration treatment of co-digestate to develop it as liquid fertilizer and the chemical changes that occur in the aerobic liquefying process. The co-digestates were divided into three types depending on their additives: swine slurry anaerobic digestate (SS AD), swine slurry 70% + cow slurry 30% anaerobic digestate (SS + CS AD), and swine slurry 70% + apple pomace 30% anaerobic digestate (SS + AP AD). The pH of all co-digestates increased rapidly after 3 days of aerobic treatment, but had slightly decreased in SS AD after 9 days and in SS + CS AD and SS + AP AD after 15 days. All co-digestates showed a strongly reduced pH between 27 and 36 days of aeration treatment. SS AD had lower pH value, dissolved oxygen (DO), NH₄-N, and NO₃-N content under aerobic conditions than other co-digestates. To assess the fully decomposed liquid fertilizer, a germination test was performed on the undiluted and diluted co-digestate using the liquid fertilizer germination index (LFGI) method. The relative germination ratio, relative root elongation, and germination index of SS AD were higher than those of the others. When the LFGI method was used for the germination test, all co-digestates showed an appropriate germination index of 70 after 60 days of aeration treatment. Thus, we suggest that the minimum period of aeration treatment for co-digestates might be 60 days to develop the fully decomposed liquid fertilizer.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.235-238
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• 2008

We examined butanol fermentation by Clostridium beijerinckii NCIMB 8052 using various hydrolyzates obtained from rice bran which is one of the most abundant agricultural by-products in Korea and Japan. In order to increase the amount of fermentable sugars in the hydrolyzates of rice bran, various hydrolysis procedures were applied. Total eight different hydrolyzates were prepared using rice bran (RB) and defatted rice bran (DRB) with enzyme or acid treatment and both. Each hydrolyzate was evaluated in terms of total sugar concentration and butanol production after fermentation by C. beijerinckii NCIMB 8052. Acid treatment yielded more sugar than enzyme treatment and combined treatment with enzyme and acid yielded even more sugars as compared to single treatment with enzyme or acid. As a result, the highest sugar concentration (33 g/L) was observed from the hydrolyzate from DRB (100 g/L) with combined treatment using enzyme and acid. Prior to perform fermentation of the hydrolyzates, we examined the effect of P2 solution containing yeast extract, buffer, minerals, and vitamins on production of butanol during the fermentation. Fermentation of the hydrolyzates with or without additionof P2 was performed using C. beijerinckii NCIMB 8052 in a 1 L anaerobic bioreactor. Although the hydrolyzates RB were able to support growth and butanol production, addition of P2 solution into the hydrolyzates significantly improved cell growth and butanol production. Highest butanol production (12.24 g/L) was observed from the hydrolyzate of DRB with acid and enzyme treatment after supplementation of P2 solution.

• Journal of Microbiology and Biotechnology
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• v.19 no.5
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• pp.482-490
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• 2009

We examined butanol fermentation by Clostridium beijerinckii NCIMB 8052 using various hydrolyzates obtained from rice bran, which is one of the most abundant agricultural by-products in Korea and Japan. In order to increase the amount of fermentable sugars in the hydrolyzates of rice bran, various hydrolysis procedures were applied. Eight different hydrolyzates were prepared using rice bran (RB) and defatted rice bran (DRB) with enzyme or acid treatment or both. Each hydrolyzate was evaluated in terms of total sugar concentration and butanol production after fermentation by C. beijerinckii NCIMB 8052. Acid treatment yielded more sugar than enzyme treatment, and combined treatment with enzyme and acid yielded even more sugars as compared with single treatment with enzyme or acid. As a result, the highest sugar concentration (33 g/l) was observed from the hydrolyzate from DRB (100 g/l) with combined treatment using enzyme and acid. Prior to fermentation of the hydrolyzates, we examined the effect of P2 solution containing yeast extract, buffer, minerals, and vitamins on production of butanol during the fermentation. Fermentation of the hydrolyzates with or without addition of P2 was performed using C. beijerinckii NCIMB 8052 in a 1-1 anaerobic bioreactor. Although the RB hydrolyzates were able to support growth and butanol production, addition of P2 solution into the hydrolyzates significantly improved cell growth and butanol production. The highest butanol production (12.24 g/l) was observed from the hydrolyzate of DRB with acid and enzyme treatment after supplementation of P2 solution.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.12
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• pp.1119-1125
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• 2010

Most of the sludge pre-treatment methods to improve the anaerobic digestibility of sludge are not practied in the fields with low economical efficiency. The venturi cavitation system (VCS) adopting hydrodynamic cavitation is simple and requires low energy. This research was conducted to investigate the optimum design and operating conditions of the VCS. The experimental results indicated that the optimum number of venturi in series was three, and the suction mode operation of the pump yielded 1.6 times higher pre-treatment efficiency per unit energy consumption than the discharge mode. The combination of venturies with different throat sizes did not affect the pre-treatment efficiency. Also, the parallel installation of the three in series venture unit yielded 30% higher pre-treatment efficiency per unit energy consumption than the single unit. Under parallel conditions, the solubilization efficiency was 5.6 mg ${\Delta}SCOD/g$ TS/kWh, which is higher than the previously reported value.

• Journal of Energy Engineering
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• v.21 no.2
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• pp.194-201
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• 2012

In this research, a sewage sludge solubilization study using electrolysis was performed as a pre-treatment for anaerobic digestion efficiency improvement. SCOD potency increased as the treatment time and electric current density increased with sludge electrolysis treatment while SCOD, TN, and TP especially showed the highest increase of 7.4 times, 1.9 times, and 1.3 times respectively at the 60 minute point of treatment. Solubilization was high at the strong acidic and alkaline status for the sewage sludge electrolysis treatment results along early stage pH, and especially, a high solubilization percentage of 32.9% was seen at pH 12. The above result shows that there was an increase of organic matter able to be used by microorganisms from sludge floc and the destruction of EPS structure due to direct and indirect oxidation following electrolysis.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.503-515
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• 2014

A lot of existing wastewater treatment plants (WWTPs) are rebuilt or retrofitted for advanced wastewater treatment processes to cope with reinforced effluent criteria of nitrogen and phosphorous. Moreover, how to treat the wasted sludge from WWTPs has been also issued since the discharge of the wasted sludge into ocean is impossible from 2011 due to the London Convention 97 protocol. These trend changes of WWTPs get a motivation to assess environmental and economic impacts from the construction stage to the waste stage in WWTPs. Therefore, this study focuses on evaluation of environmental and economic impacts of the advanced wastewater treatment processes and waste sludge treatment process by using life cycle assessment. Four advanced wastewater treatment processes of Anaerobic/Anoxic/Oxic ($A_2O$), 5 stages-Bamard Denitrification Phosphate (Bardenpho), Virginia Initiative Plant (VIP), and Modified University of Cape Town (MUCT) are chosen to compare the conventional activated sludge (CAS) and three waste sludge treatment methods of land fill, incineration, and composting are used. To evaluate environmental and economic impacts of each advanced wastewater treatment processes, life cycle assessment (LCA) and life cycle cost (LCC) are conducted based on International organization for standardization (ISO) guidelines. The results clearly represent that the $A_2O$ process with composting shows 52% reduction in the environmental impact than the CAS process with landfill. On the other hand, the MUCT process with composting is able to save 62% of the life cycle cost comparing with the CAS process with landfill. This result suggested the qualitative and quantitative criteria for evaluating eco-environmental and economic technologies of advanced treatment processes and also sludge treatment method, where their main influence factors on environmental and economic impacts are analyzed, respectively. The proposed method could be useful for selecting the most efficient and eco-friendly wastewater treatment process and sludge treatment method when retrofitting the existing WWTPs to advanced treatments.

• Membrane and Water Treatment
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• v.9 no.5
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• pp.373-383
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• 2018

Fouling by solids and microorganisms is the major obstacle limiting the efficient use of membrane wastewater treatment. In our previous study, two stages microalgae/membrane filtration system was proposed to treat anaerobic digested palm oil mill effluent (AnPOME). This two stages microalgae/membrane filtration system had showed great potential for the treatment of AnPOME with high removal of COD, $NH_3-N$, $PO_4{^{3-}}$, TSS, turbidity, and colour. However, fouling behavior of the membrane in this two stages microalgae/membrane filtration system was still unknown. In this study, empirical models that describe permeate flux decline for dead-end filtration (pore blocking - complete, intermediate, and standard; and cake layer formation) presented by Hermia were used to fit the experimental results in identifying the fouling mechanism under different experimental conditions. Both centrifuged and non-centrifuged samples were taken from the medium with 3 days RT intervals, from day 0 to day 12 to study their influence on fouling mechanisms described by Hermia for ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) filtration mode. Besides, a more detailed study on the use of resistance-in-series model for deadend filtration was done to investigate the fouling mechanisms involved in membrane filtration of AnPOME collected after microalgae treatment. The results showed that fouling of UF and NF membrane was mainly caused by cake layer formation and it was also supported by the analysis for resistance-in-series model. Whereas, fouling of RO membrane was dominated by concentration polarization.

• Journal of Periodontal and Implant Science
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• v.24 no.2
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• pp.421-432
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• 1994

The local route of antibiotic administration can accomplish higher therapeutic doses in subgingival sites than those possible by systemic therapy. This investigation assessed on the clinical and microbiological effect of 30% Minocycline loaded polycaprolactone film (Mino-strip) on rapidly progressive periodontitis. Mino-strip was applied in the periodontal pockets of 15 patients with clinically diagnosed as a rapidly progressive periodontitis. 8sites for each patient with a 5mm probing pocket depth were selected in split mouth design and were assigned into group. i.e., placebo(group 1), supragingival scaling and R/P(group 2), Mino-strip applied only(group 3), R/P and Mino-strip applied(group 4). Supragingival scaling and oral hygiene instruction were performed 1 wk before experiment. Mino-strip was applied weekly on day 0 and 7. Clinical and microbiological test were performed on day 0, 7, 14, 28, 56. In R/P and Mino-strip applied group, Gingival index, GCF volume, probing depth and loss of attachment level were significantly reduced after the first weeks following treatment. In R/P and Mino-strip applied group, the relative proportions of spirochetes and motile rods were significantly reduced and the proportions of cocci and non motile rod were correspondingly increased for eight weeks following treatment. In R/P and Mino-strip treated group, total anaerobic and aerobic bacterial count were significantly decreased for the first two weeks following treatment and streptococcus count was decreased for eight weeks following treatment. In R/P and Mino-strip applied group, P. gingivalis, P. intermedius, B. forsythus, A. actinomycetemcomitans, F. nucleatum, E. corrodens, C. rectus counts were significantly reduced after the first week following treatment. According to this study, it is appeared that 30% Minocycline-loaded polycaprolacton film was effective in the treatment on rapidly progressive periodontitis.