• Journal of Microbiology and Biotechnology
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• v.18 no.12
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• pp.1958-1965
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• 2008

A denitrifying polyphosphate-accumulating bacterium (YKP-9) was isolated from activated sludge of a 5-stage biological nutrient removal process with step feed system. This organism was a Gram-negative, coccus-shaped, facultative aerobic chemoorganotroph. It had a respiratory type of metabolism with oxygen, nitrate, and nitrite as terminal electron acceptors. The 16S rRNA gene sequence of strain YKP-9 was most similar to the 16S rRNA gene sequence of Paracoccus sp. OL18 (AY312056) (similarity level, 97%). Denitrifying polyphosphate accumulation by strain YKP-9 was examined under anaerobic-anoxic and anaerobic-oxic batch conditions. It was able to use external carbon sources for polyhydroxyalkanoates(PHA) synthesis and to release phosphate under anaerobic condition. It accumulated polyphosphate and grew a little on energy provided by external carbon sources under anoxic condition, but did neither accumulate polyphosphate nor grow in the absence of external carbon sources under anoxic condition. Cells with intracellular PHA cannot accumulate polyphosphate in the absence of external carbon sources under anoxic condition. Under oxic condition, it grew but could not accumulate polyphosphate with external carbon sources. Based on the results from this study, strain YKP-9 is a new-type denitrifying polyphosphate-accumulating bacterium that accumulates polyphosphate only under anoxic condition, with nitrate and nitrite as the electron acceptors in the presence of external carbon sources.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.2
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• pp.113-120
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• 2004

The biodegradability of organics has become essential for the design and modeling of a biological nutrient removal process. Respirometry for the batch test just with wastewater has been conducted to estimate active biomass and readily biodegradable organics in municipal wastewater simultaneously. Municipal wastewater contains significant active biomass, which is estimated about 17% of COD. Compared to the batch test seeded with sludge, the batch test just with wastewater represents a little higher readily biodegradable organics. This might be due to the different environment of the logarithmic growth of active biomass. The nitrate uptake rate test has been also performed for the estimation of the readily biodegradable organics. The nitrate uptake rate test results in a little higher readily biodegradable organics compared to the batch test seeded with sludge and similar organics compared to the batch test just with wastewater. This might be caused by the different sludge of a sequencing batch reactor process. Taking the result of the previous research into account, the readily biodegradable, slowly biodegradable, active biomass, soluble inert, and particulate inert organics are estimated about 11%, 49%, 17%, 11%, and 12% of COD, respectively.

• Journal of Environmental Health Sciences
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• v.31 no.4 s.85
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• pp.294-300
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• 2005

Food waste can be a valuable carbon source in biological nutrient removal (BNR) systems because of high C/N and C/P ratios. However, food waste should be pretreated to promote its hydrolysis rate because hydrolysis reaction would be a rate-limiting step. This study investigates the influence of the enzymatic pretreatment on acid fermentation of food waste. Solubilization of particulate matter in food waste by using commercial enzymes was examined. The acidification efficiency and the volatile fatty acids (VFAs) production potential of enzymatically pretreated food waste were also examined. The highest volatile suspended solids (VSS) reduction was obtained with an enzyme mixture ratio of 1:2:1 of carbohydrase:protease:lipase. An optimum enzyme dosage for solubilization of food waste was $0.1\%$(V/V) with the enzyme mixture ratio of 1:2:1. In the acid fermentation of enzymatically pretreated food waste, $0.1\%$(V/V) enzyme mixture dosage for pretreatment result in the maximum VFAs production and the best VFAs fraction in soluble COD(SCOD). The VFAs production at this addition level was 3.3 times higher than that of no-enzyme added fermenter. The dominant VFAs present was n-butyrate followed by acetate.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.1
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• pp.55-62
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• 2019

The respirometric technique has been used to analyze the nitrification process in a sequencing batch reactor(SBR) treating municipal wastewater. Especially the profile of the respiration rate very well expressed the reaction characteristics of nitrification. As the nitrification process required a significant amount of oxygen for nitrogen oxidation, the respiration rate due to nitrification was high. The maximum nitrification respiration rate, which was about $50mg\;O_2/L{\cdot}h$ under the period of sufficient nitrification, was related directly to the nitrification reaction rate and showed the nitrifiers activity. The growth rate of nitrifiers is the most critical parameter in the design of the biological nutrient removal systems. On the basis of nitrification kinetics, the maximum specific growth rate of nitrifiers in the SBR was estimated as $0.91d^{-1}$ at $20^{\circ}C$, and the active biomass of nitrifiers was calculated as 23 mg VSS/L and it was about 2% of total biomass.

• Korean Journal of Microbiology
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• v.46 no.2
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• pp.169-176
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• 2010

A pilot-scale wastewater treatment plant combined with rotating biological contactor and tapered aeration reactors was operated with the wastewater discharged from a food factory for 5 months. The bacterial communities of this plant were investigated by terminal restriction fragment length polymorphism (T-RFLP) and phylogenetic analysis of 16S rRNA genes. In spite of high concentration of nitrogen and phosphorus as well as organic carbon, removal efficiency of chemical oxygen demand, total nitrogen, and total phosphorus was 98%, 93%, and 95%, respectively. Bacterial community at the initial operation stage was clearly distinguished from that of the stable operation stage. The most predominant phylum in the sample of stable stage was Bacteroidetes. Major population of operation period was Haliscomenobacter, Sphaerotilus, and candidate division TM7, which were classified as filamentous bacteria. However, sludge bulking caused by these bacteria was not observed. The population that has a close relationship with Haliscomenobacter increased during the stable operation stage, emerging as the most predominant group. These results suggest that the filamentous bacteria participated in nutrient removal when using rotating biological contactor and tapered aeration reactor.

• Clean Technology
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• v.21 no.4
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• pp.257-264
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• 2015

Conventional physicochemical technologies for algae growth inhibition have economical and environmental pollution problems. This study attempted to overcome the problems by nature-friendly biological inhibition technology using fibrous carrier. The experimental results showed that the most effective carrier material, polyester, exhibited the highest biofilm thickness. The removal efficiency for nutrient salts, such as nitrogen and phosphorous, and algae growth inhibition of polyester carrier was 14.59%, 6.36%, and 77%, respectively, which is higher than for control group. These result indicate that the polyester carrier is available in eutrophic lake.

• Journal of Environmental Science International
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• v.8 no.1
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• pp.107-113
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• 1999

A new biological nutrient removal system combining $A^2/O$ process with fixed film was developed in this work and the characteristics of denitrification were especially investigated in the combined fixed film reactor(CFFR). Media was added in the anaerobic, anoxic and aerobic reactors, respectively. Tests were made to establish the effluent level of $NO_x-N$, COD, DO and nitrite effects on $NO_x-N$ removal in the CFFR by decreasing hydraulic retention time (HRT) from 10.0 to 3.5 hours and by increasing internal recycle ratio form 0% to 200%. The influent was synthesized to levels similar to the average influent of municipal wastewater treatment plants in Korea. SARAN media with a porosity of 96.3% was packed 40% / 130% / 25% based on its reactor volume, respectively. It was found that COD rarely limited dentrification in the anoxic reactor because of high $C/NO_x/-N$ ratio in the anoxic reactor, while DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent inhibited denitrification in the anoxic reactor. It was proved that the critical points of DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent were 0.15mg/L and 10%, respectively. As the internal recycle ratio increased, DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent increased. Especially, at the condition of internal recycle ratio, 200%, DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent exceeded the critical points of 0.15mg/L and 10%, respectively. Then, denitrification efficiency considerably decreased. Consequently, it was represented that the control of DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent can assure effective denitrification.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.4
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• pp.251-258
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• 2019

The physical treatment such as chemical precipitation or adsorption was usually added after biological treatment in wastewater treatment process since it was enforced to reduce the concentration of phosphate for wastewater effluent to 0.2 mg/L as P which was well known as one of main nutrient causing eutrophication in waterbody. Therefore, the new material functioned for both adsorption and disinfection was prepared with Fe and Cu, and $TiO_2$, respectively, by changing the ratio of concentration referred to tri-metal (TM). According to SEM-EDS, $TiO_2$ was 30~40% composition for any TM regardless of any synthesis condition. However, the ratio of composition for Fe and Cu was dependent on the initial Fe and Cu concentration, respectively. The removal efficiency of phosphate was obtained to 15% at low initial concentration and the maximum uptake (Q) was calculated to ~11 mg/g through Langmuir isotherm model using TM1 which was synthesized at 1000 mg/L, 1000 mg/L, and 2 g (10 g/L) for $Fe(NO_3)_3$, $Cu(NO_3)_2$, $TiO_2$, respectively. In disinfection test, the efficiency of virus removal using TM was increased with increase of dosage of TM and can be reached 98% at 0.2 g.

• Journal of Environmental Science International
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• v.20 no.7
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• pp.845-855
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• 2011

The aim of this paper is to correlate the release characteristics of marine and lake sediment with their vicinal oxic conditions. We performed lab-scale simulation experiments using field sediment and water in order to compare the release concentrations and the release rates one another. To provide a few different kinds of oxic environments we used natural air flow and some oxygen releasing compounds such as $CaO_2$ and $MgO_2$. In case of phosphates, in each oxic condition, removal of phosphorus via biological activity and that via salt precipitation with the metal ions lowered the release rates. The behavior of the nitrogen-origin salts seemed to greatly depend on the typical biological actions - growth of biomass, nitrification, and partial denitrification. Generally speaking, the control of releases of $NH_3$-N, $PO_4$-P, T-N and T-P was successful under the oxic conditions meanwhile COD, nitrates and nitrites were difficult to reduce the releases into the bulk water because of the considerable microbial oxidation. Based on typical diffusive mass transfer kinetics the changes of concentrations of the nutrients were computed for qualitative and quantitative comparisons.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.5
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• pp.480-486
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• 2006

On account of exchanging main process from chemical precipitation for MLE(Modified Ludzark-Ettinger), an external carbon source was required for supplementation of carbon source shortage that was needed biological denitrification in the S sewage treatment plant(S-STP). In this study, NUR(nitrate uptake rate), OUR(oxygen uptake rate) test and a field application test was conducted for the applicability assessment of Terephtalic acid(TPA) by-product contained about 4.7% acetate as alternative external carbon source. As the results, TPA by-product shows more rapid acclimation than methanol, 8.24 mg ${NO_3}^--N/g$ VSS/hr specific denitrification rate, 3.70 g $COD_{Cr}/g\;NO_3$ C/N ratio and 99.4% readily biodegradable COD contents. In the results of field application, the nutrient removal efficiency was high and effluent T-N concentration is 8.2 mg/L. It is concluded that TPA by-product is the proper alternative external carbon source.