• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4B
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• pp.421-426
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• 2006

The effect of initial concentration of ammonium ion ($N_0$) and active nitrifiers ($X_0$) on nitrification was examined by continuous monitoring of the ammonium removal rate. The concentration of the active nitrifiers in the culture sludge, measured by the oxygen uptake rate (OUR), was found to be 42.8% of the culture sludge. Experiments were carried out under different ratios of $N_0/X_0$, viz., 0.025 to 0.493. The results from this study show that the oxidation rate was similar under the same $N_0/X_0$ ratio despite different initial concentration of ammonium ion ($N_0$) and active nitrifiers ($X_0$). Moreover, the Contois kinetic expression which includes biomass concentration, was found to describe the mechanism behind nitrification process. The ammonium oxidation rate ($q_{Nmax}$) and half saturation constant per unit activated nitrifiers ($K_N{^{\prime}}$) were theoretically determined using the Contois expression. These values were found to be 4.32 gN/gVSS/day and 0.013 gN/gVSS respectively.

• 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.35 no.4
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• pp.294-300
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• 2013

In this study, major parameter of partial nitritation was investigated for the stable operation. In order to establish partial nitritation system, prevailing parameters such as temperature, BA (bicarbonate alkalinity) and pH were evaluated. As a result, it is inferred that appropriate bicarbonate alkalinity ratio (mg $NaHCO_3{\cdot}L^{-1}/mg$ Inf. $NH_4{^+}-N{\cdot}L^{-1}$) drives stable 50% partial nitritation at $32^{\circ}C$ and ambient temperature, respectively. Alkalinity ratio was proposed as new strategy for 50% partial nitritation without pH control in both temperature regimes. Because of the results, it was added amound of BA required only for 50% nitritation to inhibit nitratation. The effluent $NO_2{^-}-N/NH_4{^+}-N$ ratio reached almost 100% when initial bicarbonate alkalinity ratios (mg $NaHCO_3{\cdot}L^{-1}/mg$ Inf. $NH_4{^+}-N{\cdot}L^{-1}$) were 6.8 (R1) and 6.7 (R2), respectively. Polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE) results demonstrated that AOB was the dominant nitrifying bacteria and NOB was negligible after adopting process control.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.6
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• pp.727-735
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• 2007

The use of water by cities is increasing owing to industrialization, the concentration of population, and the enhancement of the standard of living. Accordingly, the amount of waste water is also increasing, and the degree of pollution of the water system is rising. In order to solve this problem, it is necessary to remove organisms and suspended particles as well as the products of eutrophication such as nitrates and phosphates. This study developed a high-end treatment engineering solution with maximum efficiency and lower costs by researching and developing a advanced treatment engineering solution with the use of Biosorption. As a result, the study conducted a test with a $50m^3/day$ Pilot Scale Plant by developing treatment engineering so that only the secondary treatment satisfies the standard of water quality and which provided optimal treatment efficiency along with convenient maintenance and management. The removal of organisms, which has to be pursued first for realizing nitrification during the test period, was made in such a way that there would be no oxidation by microorganisms in the reactor while preparing oxygen as an inhibitor for the growth of microorganism in the course of moving toward the primary settling pond. The study introduced microorganisms in the endogeneous respiration stage to perform adhesion, absorption, and filtering by bringing them into contact with the inflowing water with the use of a sludge returning from the secondary settling pond. Also a test was conducted to determine how effective the microorganisms are as an inner source of carbon. The HRT(Hydraulic Retention Time) in the nitrification tank (aerobic tank) could be reduced to two hours or below, and the stable treatment efficiency of the process using the organisms absorbed in the NAR reactor as a source of carbon could be proven. Also, given that the anaerobic condition of the pre-treatment tank becomes basic in the area of phosphate discharge, it was found that there was excellent efficiency for the removal of phosphate when the pre-treatment tank induced the discharge of phosphate and the polishing reactor induced the uptake of phosphate. The removal efficiency was shown to be about 94.4% for $BOD_5$. 90.7% for $COD_{Cr}$ 84.3% for $COD_{Mn}$, 96.0% for SS, 77.3% for TN, and 96.0% for TP.