• Journal of Korean Society of Environmental Engineers
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• v.30 no.2
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• pp.199-206
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• 2008

Simultaneous nitrification and denitrification means that nitrification and denitrification occur concurrently in the same reaction vessel under low DO concentration. Some mathematical models developed to simulate simultaneous nitrification and denitrification reaction, but they have the complex model structures or have limitations of model application. To solve these problems, if possible that predict the behavior of simultaneous nitrification and denitrification reaction by activated sludge model, structures of the model is less complex than previous models and applies the various operation conditions. But original activated sludge models have difficulties in representing the denitrification reaction under aerobic condition. So the aim of this study is to interpret simultaneous nitrification and denitrification reaction by modifying activated sludge model. Original activated sludge model No.1(ASM1) was selected and modified. The simulation result in modified ASM1 predicted appropriately for the measured data. This indicates the structures of ASM1 are properly improved for interpretation of simultaneous nitrification and denitrification reaction.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.409-413
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• 2005

A method to estimate the autotrophic maximum specific growth rate is presented in this paper. First of all, the concentration of nitrifier is simulated based on the amount of N nitrified, the sludge age and the default value for the decay coefficient. Secondly the OUR of the sludge with access of ammonia is measured. The maximum specific growth rate can be calculated as ${\mu}_{max,A}\;=\;OUR_{max,A}/Y_A$. It was demonstrated that the maximum specific growth rate of autotrophic biomass is not a constants but a time variable parameter. It is concluded that using $OUR_{max,A}$ for dynamic estimating maximum specific growth rate is a good approach and that using a constant value for the maximum specific growth rate over a longer period of time could not predict the performance of activated sludge plants.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.5
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• pp.548-555
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• 2007

The control of wastewater treatment has two merits; one is to regulate water quality of effluent and the other is to reduce the cost of wastewater treatment. The purpose of this study was to control the ammonium nitrogen in effluent that is known to cause eutrophication. The control was based on simplified ASM No. 1 which had 3 component materials and 8 coefficients, and the control method was as following. Firstly the ammonium concentration of inflow was measured and the optimal aeration time in effluent was determined according to simplified ASM No. 1 to be 1.0 mg/L. If ammonium concentration of effluent was not equal to 1.0 mg/L, the influent ammonium was corrected by adaptive control. These processes above were repeatedly performed. The SBR running aerobic-anoxic phase had been controlled for 1 month with this method. As a result, the ammonium concentration of the effluent showed in the range of $0.22\sim3.1$ mg/L with an average concentration of 1.1 mg/L. The adaptive control method used in this study was found very useful to control and predict the effluent concentration of ammonium.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.4
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• pp.409-420
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• 2007

ASM No. 1 is a very useful model to analyze wastewater treatment system removing organic carbon and nitrogen material. But it isn't adequate to control the wastewater treatment system with real time since it has many material divisions and parameters. So, the purpose of this study is the simplification of ASM No. 1 to control the wastewater treatment system. ASM No. 1 was changed with the model which has 3 material divisions(COD, $NH_4{^+}$, $NO_3{^-}$) and two phases(Aerobic and Anoxic condition). SBR was running with two phases(Phase I and II). Phase II running 20 minutes with aerobic time was used for deciding model parameters and Phase I running 12 minutes with aerobic time was used for proving the simplified model. The simplified model was compared with ASM No. 1 using data of Phase I and II. As a result of model comparison, the simplified model has enough ability to express the variation of $NH_4{^+}$ compound.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.1
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• pp.3-14
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• 2008

ASM No. 2(Activated sludge model No. 2) is very useful model to analyze the wastewater treatment which removes nitrogen and phosphorus. But, it is difficult to apply ASM No. 2 to control of wastewater treatment since it has 17 material divisions and 46 parameters. So the purpose of this study was the simplification of ASM No. 2 and the provement of simplification model. Firstly ASM No. 2 was simplified with 5 material division and three phases(Anaerobic, aerobic, anoxic phases). The simplified model was proved by R-square using track study data. As a result of provement, the values of R-square in ${NH_4}^+$ were 0.9815 in ASM No. 2 and 0.9250 in simplified model and in ${NO_3}^-$ were 0.8679 in ASM No. 2 and 0.7914 in simplified model and in ${PO_4}^{3-}$ are 0.9745 in ASM No. 2 and 0.9187 in the simplified model when the ability to express the material variation was compared by R-square. So, the simplified model has enough ability to express the variation of ${NH_4}^+$, ${NO_3}^-$ and ${PO_4}^{3-}$.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.6
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• pp.889-896
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• 2012

In this study, simulation results of nitrogen and phosphorus removals and microbial activities for an $A_2O$ process in wastewater treatment plant are presented by using Activated Sludge Models (ASMs). Simulations were performed using pre-calibrated model and layout implemented in GPS-X simulation software. The models were used to investigate variations of SRT, water temperature, DO and C/N ratio effect on nutrients removal and microbial activity. According to the simulated results, the successful nitrification required SRT higher than 10.3 days, whereas increase of $NO_3$-N loading in the anaerobic reactor caused phosphorus release by PAOs; the effluent $NH_4$-N showed rapid change between $12^{\circ}C$(21.7 mg/L) and $13^{\circ}C$(3.2 mg/L); the effluent phosphorus was increased up to 1.9 mg/L at water temperature of $25^{\circ}C$; the DO increase was positive for heterotrophs and autotrophs growths but negative for PAOs growth; the PAOs showed low activity when C/N ratio was lower than 2.5. The experimental results indicated that the calibrated models can assure the prediction quality of the ASMs and can be used to optimize the $A_2O$ process.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.1
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• pp.25-31
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• 2010

네덜란드 브리젠빈 하폐수처리장 최종방류수의 $NH_4$-N 및 TN(Total Nitrogen)농도를 방류수 수질기준인 각각 4 mg/L와 10 mg/L에 맞추기 위한 최적의 운전조건을 도출하기 위해 다양한 제어시스템이 시뮬레이션 되었다. 본 연구에 사용된 모델은 IWA(International Water Association) 활성슬러지 모델 No.1 (ASM No.1)이었고, GPS-X가 시뮬레이터로 사용되었다. 모델링을 위한 매개변수 민감도 분석결과 ASM No.1의 총 19개 매개변수 중 8개 변수 ($Y_H$, ksh, koh, $b_H$, ${\mu}_a$, $k_{NA}$, kh, ka)가 방류수 수질에 영향을 미치는 것으로 조사되었고 이들 매개변수에 대해 보정을 수행하여 사용하였다. SRT, 호기/무산소기간, 외부탄소원 주입시간 변화에 따른 방류수질 변화를 시뮬레이션하였는데, 호기/무산소 11h/1h인 조건에서 SRT가 20일에서 25일로 증가되면 $NH_4$-N가 5.0 mg/L에서 2.9 mg/L로 감소되었고 호기/무산소 2h/1h의 조건에서는 SRT증가에 따라 $NH_4$-N은 큰 감소를 보이지만, 바이패스되는 유입수량의 감소로 탈질율이 낮아 방류수 TN이 11.1~11.5 mg/L로 예측되는 결과가 도출되었다. 탈질율을 높이기 위한 아세트산 주입은 동일한 양의 아세트산을 무산소 전기간 (1h)동안 균일 주입하는 것 보다는 무산소 초기 15분내에 주입하는 것이 효율적인 것으로 나타났다.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1706-1709
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• 2010

Sewerage Treatment Plants(STPs) are complexes systems in which a range of physical, chemical and biological processes occur. Since Activated Sludge Model(ASM) No.1 was published, a number of new mathematical models for simulating biological processes have been developed. However, these models have disadvantages in cost and simplicity due to the laboriousness and tediousness of their procedures. One of the major difficulties of these mathematical model based tools is that the field-operators mostly don't have the time or the computer-science skills to handle there models, so it mainly remains on experts or special engineers. In order to solve these situations and help the field-operators, the $KM^2BM$(K-water & More-M Mass Balance Model) based on the dynamic-mass balance model was developed. This paper presents $KM^2BM$ as a simulation tools for STPs design and optimization. This model considers the most important microbial behavioral processes taking place in a STPs to maximize potential applicability without increasing neither model parameter estimation nor wastewater characterization efforts.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.9
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• pp.926-934
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• 2006

In this study, nitrate uptake rate(NUR) and oxygen uptake rate(OUR) tests were conducted for the assessment of application of Terephtalic acid(TPA) by-product as an alternative external carbon source for sewage treatment plant(STP). With the ASM1 installed in GPS-X the substrate removal characteristic was investigated with simulation by obtained data from NUR and OUR test. As a result, the fraction of RBDCOD(readily biodegradable COD) was mort than 90% and specific denitrification rate was observed about 8.00 mg $NO_3^-$-N/g VSS/hr that was similar to conventional external carbon source. In the next step, sensitivity analysis for heterotrophic biomass in ASM1 was conducted. Optimized parameters of ${\mu}_{max,H}$, $K_s$, ${\eta}_g$, and $b_H$ were 6.60/day, 23.3 mg/L, 0.88, and 0.54/day, respectively. Then, relative mean squared error(RMSE) was reduced to about 40%. Optimized parameters value were well corresponded with the substrate removal characteristics of high maximum and final endogenous specific OUR and high specific NUR.