• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.922-927
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• 1991

This study is aimed to investigate a design problem of the fuzzy logic controller for the activated sludge process(ASP) in sewage treatment. The modeling technique proposed by Sugeno is used to express the ASP effectively and identification of a fuzzy model of the ASP is carried out utilizing actual operational data obtained from a metropolitan sewage plants. The model-based fuzzy controller is designed by rules generated from the identified ASP fuzzy model. Feasibility of the designed controller is tested through computer simulations.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.209-212
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• 1990

The activated sludge process is a commonly used method for treating sewage and waste waters. The process is characterized by a lack of measurement instrumentations and control goals that are neither well defined nor well understood. In the present study the concept of fuzzy control is employed for such process in which a design method for fuzzy controller based on a multivariable fuzzy reasoning algorithms is investigated and then simulation results are presented.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.4
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• pp.508-514
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• 2004

Industrial and municipal wastewater treatment plants produce large amounts of sludge cakes for final disposal. This problem is an inevitable drawback inherent to the activated sludge process. Both the reduction of the amount of sludge produced and improvement of its dewaterability are presently very important issue also in Korea. So many pre-treatment processes have been developed in order to improve sludge dewatering efficiency. In this study the effects of hydrogen peroxide and paper sludge mixing processes were considered as reasonable alternatives to enhance sludge dewaterability. The CST of sludge was significantly decreased, and dewaterability improved by hydrogen peroxide oxidation treatment. The optimum dosage of hydrogen peroxide was proved to be 10mg/g-TS (when TS of sludge was 2%) with the conditions of pH 4 and only 1~2 minutes of reaction time. The mixing of paper sludge with sewage sludge was turned out to be very effective in reduction of sludge cake; 30% of sludge cake reduction was accomplished. Optimum mixing ratio of paper sludge was about 30%(v/v). This process also could save 25% of polymer to be required. These two alternatives are somewhat realistic, but it was concluded that paper sludge mixing process will be the best choice.

• Membrane Journal
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• v.11 no.4
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• pp.170-178
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• 2001

PVC microfiltration membrane was prepared by phase immersion method and applied to membrane bioreactor (MBR) contained activated sludge. The hydrophilicity of membrane and the pore size increase with the amount of additive(PVP) ducting the preparation of membrane. Permeation characteristics and the membrane fouling behavior were investigated by varying the internal environment in MBR using the prepared membranes. When there is a sludge bulking in MBR caused by microorganism, membrane fouling was accumulated. The cake layer resistance, R$_{c}$, of membrane increased in the order of CP-0 > CP-1.0 > CP-1.5. Rc increased up to 3.5~7 fold where the sludge bulking occurred in MBR. CP-1.5 seems to be appropriated membrane on the basis of the surface characteristics and the flux. The average flux of all the test membrane was 12(${\pm}$2) L/$m^2$hr whereas the COD removal efficiency was 98.8%. The ratio of bulking sludge and the type and the size of microorganism in operating MBR accelerate the membrane fouling and flux decline. It is concluded that the characteristic of membrane filtration depends on the hydrophilicity of membrane, the internal environment of MBR reactor and the growth factor of sludge.

• Journal of Environmental Science International
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• v.16 no.9
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• pp.1085-1090
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• 2007

The performance of EF (electroflotation) on the thickening of activated sludge were investigated using laboratory scale batch flotation reactor. In this paper, the effects of parameters such as electrode material, NaCl dosage, initial sludge concentration and electrode distance were examined. The results showed that the performance for sludge thickening of the five electrodes lay in: Pt/Ti > Ru/Ti > Ir/Ti > Ti mesh > Ti plate. The more NaCl dosage was high, the more sludge was thickened and the shorter thickening time was obtained. However, considering the final thickening time and sludge concentration, optimum NaCl dosage was 0.5 g/L. Thickening time and sludge concentration was not affected by electrode distance. In DAF (dissolved air flotation) system, optimum recycle ratio was 40% and thickening performance was lower than that of the EF.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.4
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• pp.91-97
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• 2008

The objective of this research is to investigate the effect of the addition of granular activated carbon (GAC) and granular sludge on the performance of upflow anaerobic sludge blanket (UASB) reactors for treating leachate. For the control reactor, sludge obtained from an anaerobic digester was used as a seed material. On the other hand, GAC and granular sludge were incorporated with the seed sludge in the GAC reactor and the Granule reactor, respectively. The shortest acclimation period was observed in the Granule reactor. The GAC reactor also gave comparable performance to the Granule reactor at the beginning of operation. However, as the adsorptive capacity of GAC was exhausted, the effluent COD concentration increased gradually. Once the systems were stabilized, the GAC reactor showed slightly better results than the other two reactors in terms of chemical oxygen demand (COD) removal. COD removal in all reactors was more than 90% at hydraulic retention time of 1.0 day. Furthermore, GAC reactor showed little variation in COD removal rate and remained at 95% with organic loading rate (OLR) of 4.0 to $8.2kg\;COD/m^3.d$. Initial operating period was reduced by the addition of granular sludge, while the treatment efficiency was enhanced by the addition of GAC.

• Journal of Animal Environmental Science
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• v.10 no.2
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• pp.81-86
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• 2004

This experiment was conducted to evaluate combination system of wood chip trickling system and activated sludge process. The results obtained are summarized as tallows. The trickling filter system using wood chip was used as a biological pre-treatment system for treating piggery wastewater. At pre-treatment the removal efficiencies were BOD $91\%$ CODmn $65\%$, SS $75\%$ T-N $73\%$, T-P $69\%$. After pre-treatment the removal efficiencies in activated sludge process were BOD $99\%$ CODmn $94.6\%$, SS $97.8\%$ T-N $91.1\%$, T-P $91\%$. This study shows a very stable method with pre-treatment of trickling filter using wood chip. These combined treatment system was very useful for piggery wastewater.

• Journal of environmental and Sanitary engineering
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• v.20 no.2 s.56
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• pp.12-20
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• 2005

Most of sewage treatment plants in Korea is operated for the removal of organic material. Because of low C/N ratio of domestic wastewater it is very difficult to remove nitrogen and phosphorus from wastewater. Therefore C/N ratio is key factor for the removed of nitrogen and phosphorus. PSB(photosynthetic bacteria) can remove the nutrient materials, so this study is focused on PSB characterization of nutrient removal. PSB is possible to remove nitrogen, phosphorus in anaerobic and aerobic condition. This study try to find out condition of the PSB in SBR reactor, Batch reactor. It consists of three Mode. Mode 1, 2 is to apply activated sludge process and Mode 3 is that seeded PSB in the activated sludge process. As a result of SBR process, Mode 1, 2 which was activated sludge Process showed $79\~90\%,\;66\~90\%$ of SCODcr, $94.67\~95.89\%,\;95.76\~98.56\%$ of TKN, and Mode 3 has $84\~92\%$ of SCODcr, $95.39\~99.52\%$ of TKN removal efficiency, respectively. When comparison with Mode 1, 2 and 3, most of nitrogen and phosphorus is removed at the anaerobic condition in Mode 3. but Mode 1, 2 has just revealed activated sludge process characterization. It would because of characterization of PSB.

• Korean Journal of Microbiology
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• v.47 no.1
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• pp.50-55
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• 2011

A simple and rapid method was developed for monitoring of Gram-positive bacteria in the wastewater treatment system. Culture suspensions of 4 Gram-positive and 4 Gram-negative strains were filtrated and stained with a polyethersulfone membrane filter and Toluidine Blue-O. To establish quantitative color image analysis, the intensity value of RGB (red-green-blue) color of a scanned filter image was analyzed with a photographic program. Red and green color values of Gram-positive bacteria were higher than those of Gram-negative bacteria. This method was applied to the activated sludge mixed with the Gram-positive bacteria. Although evaluation was difficult due to the irregular size and shape of flocs, the population of Gram-positive bacteria in the activated sludge could be monitored with floc dispersion technique. The more amounts of Gram-positive bacteria in the activated sludge led to the increase of red and green color values. This method provides a rapid and quantitative measurement of Gram-positive bacteria within the wastewater treatment systems.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.3 no.2
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• pp.113-119
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• 1999

The quality of the effluent from an activated sludge aeration tank can deteriorate when the substrate removal rate decreases due to an abrupt reduction in the DO concentration, which is affected by such operating conditions as the loading rate, temperature, wastewater composition, and so on. In this research, a DO control system that includes a PI (proportional-integral) controller/Hiraoka controller was developed and applied to a pilot-scale activated sludge process, then its acceptability was estimated. The applicability of the respiration rate to DO control was also estimated. The respiration rate indicated a variety of input organic loading rates, which is the main disturbance to the DO concentration in an aeration tank. When the influent concentration incrementally decreased and increased between CODcr 1,000 mg/l and 100 mg/l, the control system with a PI controller exhibited a good llperformance-the average DO concentrations were 2.00$\pm$0.14 mg/l and 1.88$\pm$0.15 mg/l (set value was 2.0 mg/l), respectively, and the settling time was just 10 minites. When the control system was operated for 4 days, the DO concentration was 1.99$\pm$0.18 mg/l and 32.6% of the air flowrate was saved. However, the fluctuations in the respiration rates and air flowrates were severe, which could be harmful to the stability of the biomass and mechanical stability of the blower. A possible approach to solve this problem may be the simultaneous control of the loading rate and DO concentration.