• Environmental Engineering Research
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• v.20 no.4
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• pp.392-396
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• 2015

This work aims to investigate the oily wastewater treatment by the electrocoagulation-flotation (ECF) and propose a mathematical model for the efficiency prediction. Cutting oil was used to prepare the synthetic oily wastewater with submicron droplet sizes. The chemical coagulation by aluminium sulfate was firstly tested following by the electrocoagulation-flotation with aluminium electrodes. Both processes gave the effective treatment performance with the efficiencies higher than 90%. However, the ECF consumed less aluminium dosage as well as produced less sludge, which were its advantage on the chemical coagulation. The performance of the ECF was found to be affected by the current density, oil concentration, and reaction time according to the analysis by the design of experiment (DOE). Finally, the prediction model was proposed by two approaches, including linear and logarithm function. The latter model gave more accuracy prediction results in terms of treatment efficiency and duration in the lag and stable stages.

• Journal of Korean Society on Water Environment
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• v.25 no.1
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• pp.120-124
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• 2009

This study was performed to investigate the application of submerged membrane bioreactor (MBR) system for biological nutrient removal of municipal wastewater. MBR bioreactor consists of four reactors such as anaerobic, stabilization, anoxic and submerged membrane aerobic reactors with two internal recycles. The hydraulic retention time (HRT), sludge retention time (SRT) and flux were 6.2 hr, 34.1 days and $19.6L/m^2/hr$ (LMH), respectively. As a result of operation, the removal efficiency of $COD_{Cr}$, SS, TN and TP were 94.3%, 99.9%, 69.4%, and 74.6%, respectively. There was no significant effect of microbial activity after the maintenance cleaning using 200 mg/L of NaOCl. Membrane filtration for the treatment of municipal wastewater was performed for longer than 9 months without chemical recovery cleaning.

• Journal of Korean Society of Water and Wastewater
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• v.8 no.1
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• pp.27-33
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• 1994

With the rapid industrialization, an ever-increasing quantity and kind of new organic compounds pose environmental problems due to their toxicity and physiological effect. However, research on the biodegradation of these compounds under anaerobic condition is very limited inspite of its efficiency and economical advantage. In this research, the pH effect on the ring cleavage of phenol under anaerobic condition was investigated, and the theory of phase separation was applied to the degradation of phenol for investigating the role of acidogenic bacteria. Results, obtained from biochemical methane potential(BMP) assay for 15.5 days of incubation, showed that acidic condition was more desirable for phenol degradation than alkaline condition. By both unacclimated methanogenic granular sludge and two mixed cultures, phenol was completely removed within six weeks of incubation with a gas conversion rate of over 86% of theoretical one. However, phenol was not degraded by unacclimated acidogenic culture, and thus it is considered as a syntrophic substrate. In case of phase separated biochemical methane potential(PSBMP) assay, in which acidogenic and methanogenic culture were seeded separately and consecutively, those that had been subjected to normal acidogens for 3 to 4 weeks showed higher gas production than those seeded with sterile or frozen culture.

• Journal of Environmental Health Sciences
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• v.33 no.5
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• pp.456-461
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• 2007

This study was carried out two point view that reuse of sludge and adsorption of benzene, toluene and o-xylene of VOCs in cast, carbonized cast and activated carbon. The cation exchange capacity of cast and carbonized cast were 59.2, 112 meq/100g, respectively. The specific surface were 560, $800m^2/g$, respectively. The average removal rates of benzene by 50g cast of 50% hydrous cast, anhydrous cast, carbonized cast, activated carbon were 15.0, 41.2, 88.2, 99.4% in 60min of retention time. The average removal efficiency of toluene by 50 g cast of 50% hydrous cast, anhydrous cast, carbonized cast, activated carbon were 12.5, 34.2, 88.2, 99.5% in 60 min of retention time. The average removal rates of o-xylene 50 g cast of 50% hydrous cast, anhydrous cast, carbonized cast, activated carbon were 8.8, 28.5, 84.8, 98.1% in 60min of retention time. The adsorption efficiency of test absorbent was in order of Activated Carbon > Carbonized Cast > Cast.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.11
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• pp.544-550
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• 2002

This paper describes a strategy of a daily optimal operational scheduling on the industrial cogeneration system. The cogeneration system selected to establish the scheduling consists of three units and several auxiliary devices which include three auxiliary boilers, t재 waste boilers and three sludge incinerators. One unit generated electrical and thermal energy using the back pressure turbine. The other two units generate the energy using the extraction condensing turbine. Three auxiliary devices operate to supply energy to the loads with three units. The cogeneration system is able to supply enough the thermal energy to the thermal load, however it can not sufficiently supply the electric energy to the electrical load. Therefore the insufficient electric energy is compensated by buying electrical energy from utility. In this paper, the evolutionary algorithms was applied to establish the optimal scheduling for the cogeneration systems. Also the GUI System was developed using established mathematics medeling and evolutionary algorithms in order that non-experts are able to establish operational scheduling. This results revel that the proposed modeling and strategy can be effectively applied to cogeneration system for paper mill.

• Journal of Environmental Health Sciences
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• v.40 no.4
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• pp.322-329
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• 2014

Objectives: The purpose of this study was to investigate the effect of BIO-CLOD on advanced wastewater treatment for enhanced removal efficiency and meeting the stringent discharge water requirements of wastewater treatment plants. Methods: Two experimental apparatuses consisting of anaerobic, anoxic and aeration tanks were operated. One included a BIO-CLOD cultivation tank. Organic and nutrient parameters and removal efficiency were analyzed by pH, BOD, CODcr, SS, T-N and T-P. Results: The average removal efficiencies of BOD, COD and SS from the apparatus with BIO-CLOD tank installation were 95.5%, 88.6% and 92.9%, respectively, and these were higher than the results from the apparatus without BIO-CLOD. The average TP removal efficiency with BIO-CLOD tank marked 56.0%, higher than the 47.3% from the apparatus without one. BIO-CLOD showed a higher performance for TN removal at 49.6%, compared to the result without BIO-CLOD of 34.3% Conclusion: By reaction with BIO-CLOD, ammonia removal was effective in the aeration tank, as was phosphorus release in the anaerobic tank. Phosphorus luxury uptake and nitrification in aeration tank proceeded smoothly. The application of BIO-CLOD can improve the decrease of odor and settleability of activated sludge in a wastewater treatment plant, as well as increase the removal efficiency of organic and nutrient materials in water.

• Asian-Australasian Journal of Animal Sciences
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• v.6 no.2
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• pp.205-209
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• 1993

A new treatment system for animal waste water has been developed as an alternative to the activated sludge process. It consists of two treatments; one is operated with 7 tanks, and the other is soil and plant cultivation bed. Aerobic microorganisms are added to the influent water in the tanks where the water is aerated so that the microbes utilize the pollutants, while sedimentation removes the indigestible solids. In the secondary treatment the water, which has already received a primary treatment, is filtered through soil where it also receives treatment by soil organisms. In addition there is transpiration of water and absorption of minerals by plants. In the primary treatment BOD, SS, coliforms (E. coli), TP and total bacteria were removed 79-99%, but COD and TN were removed only 58% and 36%, respectively. In the secondary treatment removal of nutrients proceeded further, and 93-99% of pollutants were removed. The treated waters met the quality standard of discharge water in Japan except for TN, which was in too great a concentration to meet discharge standards. This problem requires further study.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.2
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• pp.231-240
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• 2011

The objectives of this research are to investigate coagulation efficiencies of two coagulants l.e., alum and polyaluminum chloride and to understand effects of the coagulants on membrane fouling in microfiltration. The turbidity of supernatant from alum coagulation was increased with increasing doses whereas the turbidity from PACl coagulation was maintained at the low values. The observed injection volume of PACl for the same removal was approximately 30 percent less than alum, which produced a low sludge volume. The settling velocity of PACl flocs was greater than alum flocs. The results corresponded well with floc size measurements. Flux decline from alum coagulation was significant due in part to small sizes of flocs. At the low dose, alum floc had less specific cake resistance than PACl floc. However, as the dosage was increased, the increases in specific cake resistances of alum was substantial. Alum coagulation pretreatment needs careful operation to reduce membrane fouling by flocs. In general, PACl coagulants were more effective than alum coagulants for pretreatment of membrane processes because PACl showed the better performance in coagulation and membrane fouling.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11b
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• pp.290-299
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• 2005

Two decommissioning projects are carried out at the KAERI (Korean Atomic Energy Research Institute), one for the Korea research reactors, KRR-1 and KRR-2, and another for the uranium conversion plant (UCP). The concept of the management of the wastes from the decommissioning sites was reviewed with a relation of the decommissioning strategies, technologies for the treatment and the decontamination, and the characteristics of waste. All the liquid waste generated from KRR-1 and KRR-2 decommissioning site is evaporated by a solar evaporation facility and all the liquid waste from the UCP is treated together with lagoon sludge waste. The solid wastes from the decommissioning sites are categorized into three groups; not contaminated, restricted releasable and radioactive waste. The not-contaminated waste will be reused and/or disposed at an industrial disposal site, and the releasable waste is stored for the future disposal at the KAERI. The radioactive waste is packed in containers, and will be stored at the decommissioning sites till they are sent to a national repository site. The reduction of the radioactive solid waste is one of the strategies for the decommissioning projects and could be achieved by the repeated decontamination. By the achievement of the minimization strategy, the amount of radioactive waste was reduced and the disposal cost will be reduced, but the cost for manpower, for direct materials and for administration was increased.

• Korean Journal of Microbiology
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• v.28 no.4
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• pp.337-344
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• 1990

Slime sampless from 10 ratating biological contactor (RBC) plants in New Jersey were microscopically examined. Filamentous bacteria such as Type 1701, Type 0041, Type 021N, Nocardia, Beggiatoa, and Sphaerotilus, which are commonly present as suspended forms also were found in RBC slimes growing as attached forms. However, the abundance wwas much different from that of activated sludge. In RBC slimes, Beggiatoa was most frequently observed filamentous bacteria and Sphaerotilus, Type 0041, Type 1701, Type 021N and Nocardia were present in decreasing order of abundance. There were morphologically two different types of Behhiatia in RBC slimes. The statistical anaysis shows that filamentous bacterial poulations between the 100 cm inside and the outside the RBC were different in most cases with significant interactions between the location and stage.