• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.464-471
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• 2016

To investigate the effects of cardiac rehabilitation (CR) on cardiopulmonary exercise capacity in both elderly and younger patients with myocardial infarction (MI). Of the MI patients who received hospital-based CR between February 2012 and December 2015, we retrospectively reviewed the medical records of patients who continued a follow-up through the outpatient clinic. A total of 46 patients (18 elderly patients (${\geq}60years$) and 28 younger patient (< 60)) were included in this study. The subjects visited the clinic to perform aerobic exercises with ECG monitoring based on their initial exercise tolerance test outcome. The exercise capacity was measured by symptom-limited exercise tests before and after hospital-based CR. Before CR, the elderly group had a significantly lower exercise capacity in peak VO2, METs, anaerobic threshold, exercise time, respiratory exchange ratio (RER) than the younger group. After CR, elderly groups showed a significantly improved exercise capacity in exercise time, HRmax, HRrest, peak VO2, METs, anaerobic threshold, and RER. Both elderly and younger groups showed similar improvement of cardiopulmonary exercise capacity after hospital-based CR. There is a very low cardiac rehabilitation participation and referral rates with MI patients in Korea. It is considered necessary to further expand the participation of cardiac rehabilitation in elderly MI patients.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.2
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• pp.57-65
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• 2008

Wastewater containing strong organic matter is very difficult to treat by utilizing general sewage treatment plant. but the wastewater is adequate to generate biomass energy (bio-gas; methane gas) by utilizing anaerobic digestion. EcoDays Plug Flow Reactor (E-PFR), which was already proved as an excellent aerobic wastewater treatment reactor, was adapted for anaerobic food wastewater digestion. This research was performed to improve the efficiency of bio-gas production and to optimize anaerobic wastewater treatment system. Food wastewater from N food waste treatment plant was applied for the pilot scale experiments. The results indicated that the efficiency of anaerobic wastewater treatment and the volume of bio-gas were increased by applying E-PFR to anaerobic digestion. The structural characteristics of E-PFR can cause the high efficiency of anaerobic treatment processes. The unique structure of E-PFR is a diaphragm dividing vertical hydraulic multi-stages and the inversely protruded fluid transfer tubes on each diaphragm. The unique structure of E-PFR can make gas hold-up space at the top part of each stage in the reactor. Also, E-PFR can contain relatively high MLSS concentration in lower stage by vertical up-flow of wastewater. This hydraulic flow can cause high buffering capacity against shock load from the wastewater in the reactor, resulting in stable pH (7.0~8.0), relatively higher wastewater treatment efficiency, and larger volume of bio-gas generation. In addition, relatively longer solid retention time (SRT) in the reactor can increase organic matter degradation and bio-gas production efficiency. These characteristics in the reactor can be regarded as "ideal" anaerobic wastewater treatment conditions. Anaerobic wastewater treatment plant design factor can be assessed for having 70 % of methane gas content, and better bio-gas yielding and stable treatment efficiency based on the results of this research. For example, inner circulation with generated bio-gas in the reactor and better mixing conditions by improving fluid transfer tube structure can be used for achieving better bio-gas yielding efficiency. This research results can be used for acquiring better improved regenerated energy system.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.463-473
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• 2000

This research was carried out to investigate chemical pretreatment using limestone in treating abandoned metallic mine drainage with anaerobic biological treatment, and to estimate application of papermill and livestock sludge as carbon sources for SRB (Sulfate Reducing Bacterial. Capacity of anaerobic limestone bed was steeply decreased. But if limestone was utilized as pretreatment process in treating them with anaerobic biological treatment. it could look forward to stabilize system because it did initally neutralize them. Effluent SCOD in R-4 was lower than R-l~R-3 in inital HRT 5day but its concentration was high in HRT 1day after passed time. Therefore in point of durability and supply of organic matter. it seemed that R-4 was useful became organic matter in R-4 was not consumed by excessive degradation within short period. In all reactors, pH was suitable for SRB growth in whole HRT, but on the evidence of ORP, SRB was active after HRT 2day. Fixation trend of heavy meta s showed high as $SO_4{^{2-}}$ reduction efficiency increased, and $SO_4{^{2-}}$ reduction and fixation of heavy metals were relatively high in HET 2day.

• Journal of Dairy Science and Biotechnology
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• v.27 no.1
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• pp.13-18
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• 2009

We confirmed methane production and reduction of pollution during anaerobic digestion of milk waste and analyzed the economic potential of using milk waste as a renewable energy source. The milk waste sludge was obtained from the Pasteur milk factory and processed by anaerobic digestion to produce methane. The methane production from two completely mixed tank reactors with an effective capacity of 6 ${\ell}$, 15 days of hydraulic retention time (HRT), and a mid-temperature of $35^{\circ}C$ averaged 4.11 ${\ell}$/day. The total chemical oxygen demand (TCOD) during production decreased from an initial 31,416 mg/${\ell}$ to 13,500 mg/${\ell}$, showing a maximum TCOD removal efficiency of 60%. When HRT was reduced to 12 days, methane production increased by 44% under a high-temperature condition of $55^{\circ}C$. An economic analysis based on these results was applied to a Korean milk factory of typical size and demonstrated that the installation of an anaerobic digester could provide sufficient economic profit.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.3
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• pp.5-13
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• 2016

This study investigated the environmental and economical assessment for sewage sludge treatment options including biogasification, incineration, carbonization, drying, and solidification. For the economical feasibility the 30 plants with anaerobic digestion treatment and the 17 plants without anaerobic digestion treatment were investigated. In regarding to the environmental assessment, the air emission pollutants (SOx, NOx, etc) from incineration and carbonization plants were assessed and 1~34 % of emission limits was emitted. Drying and solidification plants emitted about 30 % of odour limits. And the rest of the pollutants were emitted either at not-detectable level or at below the limits. When the by-products from the solidification treatment was used as landfill cover materials, the unconfined compression strength could be below the limit and it could cause an unsafe condition for those passing vehicles and the possibility of the ground subsidence. There has been a maintenance difficulty due to frequent blockage and operational failure. The result of the comparison of sewage sludge treatment options showed that anaerobic digestion+incineration was the most economically feasible considering incineration and drying. For smaller treatment capacity, solidification was the most economically feasible considering carbonization and solidification and anaerobic digestion+carbonization was the most economically feasible considering carbonization and solidification.

• Journal of the Korea Organic Resources Recycling Association
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• v.30 no.4
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• pp.27-40
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• 2022

In this study, the anaerobic digestion potential and thermo-chemical pre-treatment were evaluated for efficient anaerobic co-digestion of dewatered sludge(DS) and food waste(FW). As a result, the degradable organic matter concentration and methane yield of FW were evaluated to 2.2 and 1.3 times higher than that of DS, respectively. In order to increase the amount of biogas production, it was determined that it is desirable to increase the mixing ratio of FW. The efficiency of thermo-chemical pre-treatment was evaluated for the reaction temperature, NaOH concentration, reaction time and mixture ratio. As a result of evaluation through pre-treatment efficiency and dehydration capacity, the optimum pre-treatment conditions were evaluated as follows: reaction temperature 140℃, NaOH concentration 60 meq/L, reaction time 60 min, mixture ratio 1:5(DS:FW). The gas production rate and methane yield increased 1.6 and 1.5 times, respectively, compared to before and after applying the optimum pre-treatment. Therefore, it is necessary to increase the mixing ratio of food waste for efficient anaerobic co-digestion of DS and FW. and it is necessary to increase the solubilization efficiency of waste by application of pre-treatment.

• Advances in environmental research
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• v.7 no.2
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• pp.73-85
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• 2018

The anaerobically digestion and agricultural application of organic wastes was conducted using food wastes and cow dung. Twenty kilograms each of the feed stocks was added into two 30 liters-capacity batch digesters. The anaerobic digestion was carried out within a temperature range of $25-31^{\circ}C$ for a retention time of 51 days. The results showed a cumulative gas yield of 5.0 bars for food waste and no gas production for cow dung within the retention time. Bacteria such as Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Proteus vulgaris and Clostridium sp were isolated. Fungi isolated included Aspergillus niger, Aspergillus nidulan, Trichophyton rubrum and Epidermophyton flocossum. The non-dispersive infrared (NDIR) analysis of the biogas produced confirmed that the gas consisted of $CH_4$, $CO_2$ and $H_2$. Statistical analysis revealed there was no significant correlation between temperature and biogas produced from the organic wastes (r= 0.177, p = 0.483).The organic wastes from the biogas production process stimulated maize growth when compared to control (soil without organic waste) and indicated maximum height. The study therefore reveals that food waste as potential substrates for biogas production has a moderate bio-fertilizer potential for improving plant growth and yield when added to soil.

• Membrane and Water Treatment
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• v.3 no.2
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• pp.113-121
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• 2012

Up-flow multi-layer bioreactor (UMBR) is a hybrid system using dual sludge that consists of an up-flow multi-layer bioreactor as anaerobic/anoxic suspended growth microorganisms followed by an aeration tank. The UMBR acts as a primary settling tank, anaerobic/anoxic reactor, thickener which requires low energy due to mixing by up-flow stream. This study focused on using a pilot UMBR plant with capacity of 20-30 $m^3$/day for domestic wastewater in HCMC. HRTs of UMBR and aeration tank were 4.8 h and 7.2 h, respectively. The average MLSS of UMBR ranged from 10,000-13,600 mg/l SS. Internal recycle rate and sludge return were 200-300% and 150-200%, respectively. The results obtained from this study at flow rate of 20 $m^3$/day showed that removal of COD, SS, TKN, N-$NH_4$, T-N, and color were 91%, 87%, 86%, 80%, 91% and 91%, respectively.

• Journal of Microbiology and Biotechnology
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• v.31 no.11
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• pp.1519-1525
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• 2021

Hexavalent chromium (Cr(VI)) is recognized to be carcinogenic and toxic and registered as a contaminant in many drinking water regulations. It occurs naturally and is also produced by industrial processes. The reduction of Cr(VI) to Cr(III) has been a central topic for chromium remediation since Cr(III) is less toxic and less mobile. In this study, fermentative Fe(III)-reducing bacterial strains (Cellu-2a, Cellu-5a, and Cellu-5b) were isolated from a groundwater sample and were phylogenetically related to species of Cellulomonas by 16S rRNA gene analysis. One selected strain, Cellu-2a showed its capacity of reduction of both soluble iron (ferric citrate) and solid iron (hydrous ferric oxide, HFO), as well as aqueous Cr(VI). The strain Cellu-2a was able to reduce 15 μM Cr(VI) directly with glucose or sucrose as a sole carbon source under the anaerobic condition and indirectly with one of the substrates and HFO in the same incubations. The heterogeneous reduction of Cr(VI) by the surface-associated reduced iron from HFO by Cellu-2a likely assisted the Cr(VI) reduction. Fermentative features such as large-scale cell growth may impose advantages on the application of bacterial Cr(VI) reduction over anaerobic respiratory reduction.

• Journal of Korean Society on Water Environment
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• v.26 no.5
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• pp.816-821
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• 2010

It has been achieved 109.1 kg/d of BOD reduction that is equivalent to the amount of BOD loading discharged from 21,880 persons and dramatic decrease of the fallout ratio against water quality of effluent, from 42% to 9%, through technical support on ISTPs to be applied by the ISMSGA at the upper area of Geongan river in Yong-In city. It was clearly revealed that the most efficient configuration for ISTP was a series of anaerobic tank, equalization basin, aerobic tank, sedimentation tank, and then effluent tank. Also, the major causes on the fallout ratio of ISTP resulted in the lack of management (67.5%) and imperfect facilities (32.5%). Then, when compared the quantity of water supply with the design capacity of ISTP, the design capacity was estimated as 1.8 or 2.4 folds larger than the real quantity of water supply so that it is essential to punctually consider the key factors such as an estimation methods, the specificity of commission operator and construction by high systematic technologies to improve the water quality for the future.