• Journal of Environmental Science International
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• v.12 no.1
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• pp.55-61
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• 2003

This study was carried out to obtain the operating characteristics of SMMIAR process for biological nitrogenㆍphosphorus removal. SMMIAR was operated at HLR(Hydraulic loading rate) of 39.6, 52.8, 63.4 and 79.2 $\ell$/$m^2$/d respectively and the operating parameters such as intermittent aeration time ratio of aerobic/anoxic, DO and microorganism concentration were changed to confirm the optimum operating condition. The concentrations of the wastewater BOD, TN(Total nitrogen) and TP(Total phosphorus) were 150, 30 and 7.5mg/$\ell$ respectively. Achieving better removal efficiencies of BOD, TN and TP up to 90, 85.4 and 95.4% respectively, we must keep in operation condition of SMMIAR by 0.75 of time ratio of aerobic/anoxic and by minimum 45 minutes of oxic period simultaneously.

• Journal of Korean Society on Water Environment
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• v.18 no.4
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• pp.401-409
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• 2002

In this study, to evaluate the applicability of ORP and pH as process control parameters for an intermittent aeration process, a 200L/d bench-scale plant was installed and operated for 90 days. It was fed with synthetic wastewater which contained $COD_{Cr}$ : 400mg/L, TN : 40mg/L and TP : 7mg/L. ORP & pH were measured on-line and compared with the variation of nutrient concentrations. As the results, both of the ORP and pH were able to monitor successfully nitrification and denitrification. Bending-points on the ORP curve and peak points on the pH curve corresponded to the termination of nitrification and denitrification. For P uptake and release, pH was the best indicator for performance evaluation. The aerobic pH apex was appeared when P uptake was accomplished and there was a relationship between the P release and pH variation. But the pH curve needed filtering because there were many noises on it. In this study, the shape of the ORP & pH curves were varied as the operating conditions such as aeration rates and organic loads were changed. It allowed the operating states of biological systems to be effectively evaluated. If it is properly managed to show the bending points and peak points clearly, the on-line monitoring of ORP & pH will be a reliable and effective technique for process control of intermittent aeration processes.

• Journal of Environmental Health Sciences
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• v.34 no.3
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• pp.233-239
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• 2008

In order to improve reactor performance of existing sewage treatment plants, the feasibility of enhancing reactor performance by bioaugmentation using EM as bioaugmentation agent and the effects of anoxic: oxic time ratio on reactor performance were investigated. Continuous and intermittent aeration modes were compared under the 6 hr of HRT. Three different types of intermittent aeration modes, that is, 15 min, of anoxic:45 min of oxic, 30 min of anoxic: 30 min of oxic, and 45 min of anoxic: 15 min oxic respectively were chosen as test modes to study the effects of anoxic : oxic time ratios on reactor performance. The optimum anoxic: oxic time ratio was 30 min:30 min when considering simultaneous removal of organic, nitrogen and phosphorus. When applying EM into a continuously aerated reactor under the varying dosing rates of 50-200 ppm, reactor performance in terms of organic and nitrogen removal efficiencies was not improved at all. Nitrogen removal efficiency was increase when the EM dosing rate was increased. However the degree of improvement was slight when the EM was injected above 100 ppm. However optimum phosphorus removal was found at the EM dosing of 200 ppm. Thus it was found that optimum injection concentration of EM is 200 ppm. It is apparent that putting EM into a sewage treatment plant significantly affects the T-N removal efficiency of the reactor by enhancing denitrification efficiency especially in operational conditions of relatively long anoxic periods. To achieve reciprocal condition in a reactor with intermittent aeration it is necessary to enhance the reactor performance by EM injection. In the case of modifying existing continuously aerated reactors into intermittent aerated reactors, it is obvious that operating costs of aeration would be reduced by reducing aeration time when compared with existing conventional sewage treatment plants.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6B
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• pp.669-675
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• 2006

Intermittent aerobic digestion experiments using a sequencing batch reactor (SBR) were carried out in this study. Aeration ratio was found to be an important operation factor for the reduction of solids and nitrogen. As the sludge digested, organic nitrogen was released from the solids and oxidized to nitrate nitrogen. Biological denitrification was also significant and the denitrification rate was limited by aeration ratio. Under the condition of 0.25-0.75 of aeration ratio, acclimation of ammonia nitrogen was not observed and pH were preserved near neutral in the intermittent aerobic digestion. As the aeration ratio increased, solids reduction was increased whereas dissolved nitrogen removal was decreased. Based on the experiments, 17-2% of VSS reduction and over 80% of dissolved nitrogen removal were practicable by intermittent aerobic digestion using a SBR when the MSRT were designed 8-32 days and aeration ratio was operated about 0.25-0.75.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1B
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• pp.113-118
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• 2006

Cost estimation of an intermittent aerobic digestion technology was carried out in this study. Aeration ratio is one of the most important design factors and it affects installation and power consumption cost. For the purpose, digestion efficiency was fixed at 35% of SS reduction and the reactor type was assumed a 2-chamber sequencing batch reactor (SBR). Installation cost and power consumption cost were evaluated and converted in terms of present value that could reflect the rate of discount and the rate of economic growth. The lower aeration ratio needs higher installation cost but lower power consumption cost. From the point of only installation cost, conventional aerobic digestion is cheaper than intermittent aerobic digestion. But intermittent aerobic digestion is better economical for more than 10 years of estimated service life. The optimal aeration ratio was dependent on the service life and it was lower as the estimated service life increased. For the 45 years as the service life, the optimal aeration ratio was estimated 0.3 and the total cost was 64% of the conventional aerobic digestion.

• Journal of Animal Environmental Science
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• v.2 no.2
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• pp.123-133
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• 1996

Recently, a greater interest has been placed on the methods of acration control for management of maloders during composting. This study was performed to evaluate the influence of the intermittent aeration method on the composting temperature and chemical components. Combinatoins of cattle manure and rice hulls were placed on a batch composter(3,150-L size) practically designed. The chemical properties of the produced compost were suitable for plant growth, when composting temperature was maintained in the range from 45 to $66^{\circ}C$ for 42 days. It should be noted that cooling effect of intake air was not significant because air temperature was as high as $30^{\circ}C$. Heat and aeration loss from the composter did not affect biomass decomposition by microbes during composting. Mixtures of materials with C/N ratios higher than 30 required longer composting period.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.315-318
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• 2002

This study was performed to evaluate the effects of air flow rate and aeration mode on the treatment of bioventing for diesel-contaminated soil. Initial concentrations of diesel-contaminated soils were about 2,500 and 9,000mg/kg. Air flow rates were 30, 60, and 100mL/min, and air was injected in the continuous and the intermittent modes. TPH removal efficiency of intermittent aeration mode was higher than that of continuous aeration mode. Greater air flow rate than the value of guidance book was needed for bioventing.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.4
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• pp.445-452
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• 2004

Intermittent deep draw artificial circulation system is one of the most widely used destratification systems to control algal bloom in reservoirs in Korea. However, there have been neither theoretical background of design criteria nor operation guide line for efficient application of the system available for such systems. A design method was developed to calculate required compressor capacity and number of circulation units considering physical interactions between stratified water layers and plumes induced by the intermittent deep draw artificial circulation system. The program was tested with data observed in Yeoncho Lake. The results indicated that the developed method can applied in the fields successfully. Further validation processes would improve design and operation methods.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.2
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• pp.161-170
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• 2014

It is essential to decrease energy consumption and excess sludge to economically operate sewage treatment plant. This becomes more important along with a ban on sea dumping and exhaustion of resource. Therefore, many researchers have been study on energy consumption reduction and strategies for minimization of excess sludge production from the activated sludge process. The aeration cost account for a high proportion of maintenance cost because sufficient air is necessary to keep nitrifying bacteria activity of which the oxygen affinity is inferior to that of heterotrophic bacteria. Also, additional costs are incurred to stabilize excess sludge and decrease the volume of sludge. There were anoxic, aerobic, membrane, deairation and concentration zone in this MBR process. Continuous aeration was provided to prevent membrane fouling in membrane zone and intermittent aeration was provided in aerobic zone through ammonia sensor. So, there was the minimum oxygen to remove $NH_4-N$ below limited quantity that could be eliminated in membrane zone. As the result of this control, energy consumption of aeration system declined by between 10.4 % and 19.1 %. Besides, we could maintain high MLSS concentration in concentration zone and this induced the microorganisms to be in starved condition. Consequentially, the amount of excess sludge decrease by about 15 %.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.2
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• pp.203-209
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• 2015

The purpose of this study is to estimate the applicability of a stable anaerobic digester using a separator membrane to the preprocessing thickening process. The results of the experiments showed about a 47.16% weight loss rate for the sludge under anaerobic condition, and about 41.17% under intermittent aeration condition. The concentrations of rejection water were $SCOD_{Cr}$ 25 mg/L, T-N 16.6 mg/L, and T-P 1.4 mg/L on the average under the intermittent aeration condition, which were lower than the concentrations of rejection water under an anaerobic condition. As for the factors affecting the reduction of the flux, correlation analyses of TTF, MLSS, $SCOD_{Cr}$, and $EPS_{Protein}$, $EPS_{Polysacchride}$ resulted in -0.97, -0.95, -0.84 and -0.86, -0.95, respectively, which showed that TTF had the highest correlation to the reduction of the flux. In addition, it was concluded that MLSS, $SCOD_{Cr}$ and $EPS_{Protein}$, $EPS_{Polysacchride}$ also have close correlations. The results are considered to show that, in the case of the process using a tubular membrane in the preprocessing process of an anaerobic digester, an intermittent aeration condition of the thickener considering the contamination of the membrane and load of rejection water is appropriate for the stable preprocessing process.