• Asian-Australasian Journal of Animal Sciences
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• v.13 no.5
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• pp.698-701
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• 2000

To prevent surface and underground water pollution, wastewater treatment is essential. Four bench-scale activated sludge units (10 L operational volumes) were operated at 5, 10 and $20^{\circ}C$ for evaluation of treatment efficiencies with typical wastewater from swine housing. The units were set for a 24-hour cycle. As compared to the conventional process, high removal efficiencies for organic substances, nitrogen and phosphorus in swine wastewater were obtained simultaneously with an intermittent aeration process (lAP). The NOx-N produced during an aeration period was immediately reduced to nitrogen gas (e.g. $N_2$ or $N_2O$) in the subsequent non-aeration periods, and nitrification in aeration periods occurred smoothly. Under these conditions, phosphorus removal occurred with the release of phosphorus during the non-aeration periods followed by the excess uptake of phosphorus in the activated sludge during aeration periods. It was confirmed that the lAP had a better ability to remove pollutants under both low temperatures and high nitrogen loading conditions than the ordinary method did. In addition to that, the total emission of $N_2O$ from lAP was reduced to approximately 1/50 of the conventional process for the same loading. By adopting an adequate aeration programme for individual swine wastewater treatment, this system will provide a promising means for nitrogen and phosphorus control without pH control or addition of methanol.

• Environmental Engineering Research
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• v.25 no.3
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• pp.400-408
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• 2020

Hydrodynamic study of Activated Sludge Process (ASP) is important to optimize the reactor performance and detect anomalies in the system. Residence time distribution (RTD) study has been performed using LiCl as tracer on a pilot scale aeration tank (AT) and ASP, treating the pulp and paper mill effluent. The hydraulic performance and treatment efficiency of the AT and ASP at different operating parameters like residence time, recycle rate was investigated. Flow anomalies were identified and based on the experimental data empirical models was suggested to interpret the hydrodynamics of the reactors using compartment modelling technique. The analysis of the RTD curves and the compartment models indicated increase in back-mixing ratio as the mean hydraulic retention time (MHRT) of the tank was increased. Bypassing stream was observed at lower MHRT. The fraction of dead zone in the tank increased by approximate 20-25% with increase in recycle rate. The fraction of the stagnant zone was found well below 5% for all performed experiments, which was under experimental error. The substrate removal of 91% for Chemical oxygen demand and 96% for Biochemical oxygen demand were observed for the ASP working at a hydraulic mean residence time 39 h MRT with a 20% recycling of activated sludge.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.2
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• pp.179-182
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• 2008

The KIDEA process, occurred in single reactor, is operated by three consequential steps, i.e., aerobic, settling, and discharge while introducing wastewater into the bottom of reactor continuously. It could accomplish biological oxidation (BOD), nitrification, denitrification (T-N), phosphate removal (T-P), and solid separation (SS) through the operational mode mentioned. Especially, this system has removed the T-P by wasting certain amount of sludge at the end of aeration phase during 5~10 minutes and not returned the activated sludge into the reactor, that is, no RAS (Return Activated Sludge). All running mode and instrumentation were controlled by the PLC equipment automatically. In this study, therefore, we have evaluated T-P removal efficiency and moisture content (MC) performance under the different excess sludge wasting mode. T-P track study and MC with TS concentration were analyzed during aerobic and settling phase. It has revealed that there was no significant difference of released T-P concentration between the first case which waste the sludge at the end of aerobic phase (0.2mg/L) and the second case which waste the sludge at 40 min of settling phase (0.25mg/L). Also, dewatering duration and MC have decreased 1.7% when TS concentration was increased from 0.31% to 0.5% during aerobic condition. Hence, it has concluded the system performance was less influenced by the operation time change of PLC program.

• Journal of Environmental Health Sciences
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• v.32 no.4 s.91
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• pp.336-341
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• 2006

The biological wastewater treatment system is known to have an important role in reducing the quantify of enteric virus in water environments. To clarify the roles of activated sludge microbes in decreasing the virus infectivity, the behavior of the virus in bacteria, protozoa, and metazoa was examined by pure or mixed culture system using poliovirus type 1(Lsc, 2ab strain). In the bacterial culture systems, the virus infectivity in the liquid phase decreased by a reversible adsorption of the virus to the bacteria or bacterial flocs. On the other hand, in the protozoa and the metazoa culture systems using T. pyriformis and P. erythrophthalma, respectively, with a variety of bacterial strains as prey, the main virus decrease mechanism of reversible adsorption in early stage was changed to irreversible predation, which was not eluted in this study. The virus decrease was more effective in the P. erythrophthalma culture system, which had high predation and floc forming abilities. However, in the mixed culture system of Z. ramigera and P. erythrophthalma, the more rapid reversible adsorption of virus to Z. ramigera flocs preceded the irreversible predation of P. erythrophthalma.

• Journal of Korean Society of Water and Wastewater
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• v.9 no.2
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• pp.84-96
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• 1995

The dewatering characteristics of the sewage sludge was investigated through the experimental observations and model simulations. The activated sludge and the anaerobically digested sludge were examined for the dewaterability evaluation within the pressure range of $0{\sim}10^6N/m^2$. Modified Buchner funnel test and compression test by the consolidometer were conducted to evaluate average specific resistance, porosity, and moisture percentage of filter cake. Shirato's technique of compression-permeability test was followed for the pressure range lower than about $10^2N/m^2$. The flocculation effects on sludge dewatering was also examined for ferric chloride and polymeric flocculant. The application of hydrated lime which can be used for flue-gas desulfurization showed improved moisture percentage, and was thought to have positive feasibility in combined system of sludge dewatering and incineration. Determined characteristic constants were applied to Tiller's cake filtration model to simulate liquid pressure distribution and porosity distribution in cake. Model simulations showed a sharp drop of the porosity close to the cake-medium interface for the highly compressible material such as the activated sludge and the anaerobically digested sludge.

• Journal of Korean Society on Water Environment
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• v.22 no.2
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• pp.264-270
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• 2006

In this research, volume reduction of activated sludge using electrolysis was studied to find an optimum condition using lab scale experiments. Wasted sludge was treated by electrolysis with controlling current density, chloride concentration, electrode distance, and reaction time. Volume of return sludge was reduced by 9.79% in average while maximum was 16.7%. Sludge volume reduction efficiency was affected by current density and reaction time. It was reversely proportional to the electrode distance. Especially current density was effective on the system performance significantly. Electric conductivity, salinity and COD were increased by electrolysis implying sludge disintegrated and converted to COD in part. An empirical equation for total solid removal efficiency by electrolysis was proposed by multiple linear regression analysis as: $TS_{rem}$(%) = 5.534 ${\times}$ current density (A/l) + 0.178 ${\times}$ reaction time (m) + 2.758.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.4
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• pp.480-485
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• 2004

Fatty acid methyl ester (FAME) technology was evaluated as a monitoring tool for quantification of Nocardia amarae causing a nuisance foaming problem in activated sludge process. The identified signature peak was 19:1 alcohol as a reliable unique peak to N. amarae. Chemostat study revealed that the distribution and quantity of fatty acid peaks were dependent on the growth stage of Nocardia. The FAME results were similar for two relatively high dilution rates; however, the amounts of signature peaks extracted from the 4 and 6 day cultures were significantly higher. This dependence of signature peaks on the physiological state of the organism may be a useful information to assess the health of microbial populations in activated sludge. A laboratory scale batch foaming potential experiment provided a critical foaming level depending on Nocardia population. This critical Nocardia level determined in this study was in terms of either the threshold filament intersections number or the threshold signature FAME amount. The threshold peak area of signature FAME (19:1 alcohol) and corresponding filament counts were 430PA/mg VSS and $1.45{\times}10^6$ intersections/g VSS, respectively. The threshold signature FAME level could be effectively applied as a criterion for diagnosing foam occurrence in activated sludge system.

• Membrane Journal
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• v.24 no.3
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• pp.249-257
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• 2014

This experiment was carried out for a laboratory scale activated sludge bioreactor equipped with submerged flat sheet membrane using the synthetic wastewater. The membrane system for the activated sludge solution of MLSS 5,000 mg/L was operated with constant permeate flux by continuously permeating and periodically 10 minute-permeating/2 minute-resting modes, respectively. The transmembrane pressure was measured as the permeate flux increased from 10 to $25L/m^2{\cdot}hr$ under the constant air flowrate 0.25 L/min. Also, the complete blocking, standard blocking, intermediate blocking, incompressible cake and linear compressible cake fouling models were retrofitted for the experimental data in order to determine the state of the membrane fouling. Because the transmembrane pressure fluctuated as a pulse shape for every period of 10 minute-permeating/2-minute resting mode, the membrane fouling models were separately applied for the maximum and minimum connecting lines. The linear compressible cake fouling model for the activated sludge cakes was the best fitted with the experimental results from the above five models.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.11
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• pp.1477-1485
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• 2018

There are two major issues for activated sludge process in sewage treatment plant. One is how to make sewage be more clean and the other is the energy saving in sewage treatment process. The major monitoring sewage qualities are chemical oxygen demand, phosphorus, nitrogen, suspended solid in effluent. These are transmitted to the national TMS(Telemetry Monitoring System) at every hour. If these exceed the environmental standard, the environmental charges imposed. So, these water qualities are to be controlled below the environmental standard in operation of sewage treatment plant. And recently, the energy saving is also important in process operation. Over 50% energy is consumed in blowers and motors for injection oxygen into aeration tank. So, with the water qualities to be controlled below the environmental standard, the energy saving also is to be accomplished for efficient plant management. Almost researches are aimed to control water quality without considering energy saving. AI techniques have been used for control water quality. AI modeling simulator provided the optimal control inputs(blower speed, waste sludge, return sludge) for control water quality. Blower speed is the main control input for activated sludge process. To make sewage be more clean, the excessive blower speed is supplied, but water quality is not better than the previous. In results, non necessary energy is consumed. In this paper we propose a new method that the energy saving also is to be accomplished with the water qualities to be controlled below the environmental standard for efficient plant management. Water qualities in only aeration tank are used the inputs of fuzzy models. Outputs of these models are chemical oxygen demand, phosphorus, nitrogen, suspended solid in effluent and have the environmental standards. In test, we found this method could save 10% energy than the previous methods.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.2
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• pp.104-116
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• 1996

Anaerobic digestion is generally used for the treatment of volatile organic solids such as manure and sludge from waste water treatment plants. However, the reaction rate of anaerobic process is slow, and thus it requires a large reactor volume. To minimize such a disadvantage, physical and chemical pre-treatment is generally considered. Another method to reduce the reactor size is to adopt different reactor system other than CSTR. In this paper, the effects of heat pre-treatment and reactor configurations on the anaerobic treatability of volatile solids was studied. Carrot, kale, primary sludge, and waste activated sludge was chosen as the test materials, and the BMP method was used to evaluate the maximum methane production and first order rate constants from each sample. After the heat treatment at $130^{\circ}C$ for 30min., the measured increase in SCOD per gram VS was up to 394 mg/L for the waste activated sludge. However, the methane production potential per gram VS was increased for only primary and waste activated sludge by 17-23%, remaining the same for carrot and kale. The overall methane production process for the tested solids can be described by first order reactions. The increased in reaction constant after heat pre-treatment was also more significant for the primary and waste activated sludge than that for carrot and kale. therefore, the heat pre-treatment appeared to be effective for the solids with high protein contents rather than for the solids with high carbohydrate contents. Among the four reactor systems studied, CSTR, PFR, CSTR followed by PFR, and PFR with recycle, CSTR followed by PFR appeared to be the best choice considering methane conversion rate and the operational stability.