Kyungik Gil

Removal of Reactive Dye Using UV/TiO2 in Circular Type Reactor

Abstract Photocatalytic degradation of reactive dye, Red 120, was carried out on TiO2 particles as photocatalyst under UV irradiation. In this experiment, comparison on the removal of reactive dye by photolysis using UV light alone, photocatalyst adsorption using TiO2 alone and photocatalysis using UV light with photocatalysts as well as the effect of experimental parameters such as the number of column employed, intensity of the light, pH and TiO2 dosage affecting the reaction efficiency of photocatalytic degradation of reactive dye in circular type reactor was examined. The results of this indicate that with both UV light illumination and TiO2 present, reactive dye was more effectively eliminated than with either UV or TiO2 alone. Photocatalytic degradation of reactive dye increased linearly with increasing UV light intensity. However, over 18 mW cm−2 of UV light intensity, the efficiency reached a plateau. The photocatalytic degradation rate was greater in acid media than in alkaline media. Photocatalytic removal efficiency of reactive dye increased with increasing TiO2 dosage. However, over 1.5 g L−1 of TiO2 dosage, the efficiency reached a plateau.

Correlation between nitrite accumulation and the concentration of AOB in a nitritation reactor

AbstractNitritation is an innovative biological nitrogen removal method in wastewater, and it has the advantages of energy and economy. The correlation between a nitrite conversion rate and the gene copy numbers of ammonia oxidizing bacteria (AOB) in a nitritation reactor was examined to measure the effectiveness of removing a nitrogen content in a biological nitrogen removal process, using a biological process of nitritation. A laboratory scale reactor was prepared and operated for over a year, using digester supernatant to induce a stable nitritation, and to optimize the operational conditions by adjusting various operating factors. The relationship between operational results of nitritation reactor and the AOB gene copies was approximated through identification and quantitative analysis of AOB. A stable nitritation can be artificially led with the control of SRT, while treating anaerobic digester supernatant from MWTPs. And AOB gene copies showed a correlation with free ammonia (FA) inhibition and performance of nitritation, and AOB activity. Thus, AOB gene copies were found important when it comes to analyzing nitritation.

Effect of anaerobic digestion on the high rate of nitritation, treating piggery wastewater

The amount of piggery wastewater as domestic livestock is increasing. The volume of piggery wastewater produced is less than the volume of other wastewaters, but piggery wastewater has a heavy impact on wastewater streams due to an extremely high concentration of nitrogen and COD. In this study, laboratory reactors were operated using piggery wastewater and the effluent of anaerobic digester from piggery wastewater plants. The purpose of this study was to induce the nitritation process, which is an economically advantageous nitrogen removal method that converts ammonium nitrogen into nitrite. The results showed that the effluent of anaerobic digester from piggery wastewater was more efficient than raw piggery wastewater in terms of inducing nitritation. It can be deduced that nitritation is largely affected by an organic fraction of piggery wastewater. It can also be concluded that a small amount of biodegradable organic matter in piggery wastewater is efficient in inducing nitritation.

Modelling of inhibition of nitrite oxidation in biological nitritation processes by free ammonia

To understand nitrite build-up in the nitritation process, the inhibition kinetics of free ammonia (FA) on nitrite oxidation were investigated. FA inhibition on nitrite oxidation was the key factor of nitrite build-up and its type was mixed inhibition. Therefore, the mixed inhibition model should be adapted to a Michaelis–Menten equation to set up a process rate equation for nitrite oxidation in the nitritation process.

Non-point sources analyses in paved areas using statistical methods: case study of vortex type

Abstract During a dry period, many kinds of pollutants are accumulated on the surface of paved roadways, and these are swept into nearby waterways when rain falls. Particularly when the pollutants are toxic heavy metals, the damage they cause to the water system could be significant. This study evaluated the removal efficiency of vortex-type treatment facilities in Yongin City, Gyeonggi Province, South Korea, over a 2-y period from 2006 to 2007. Grain-size analyses of Zn, Pb, and Cd, which are particulate materials and heavy metals, were also conducted. Monitoring results showed removal efficiencies ranging from 9% to 65% for TSS, 0–55% for BOD, 1–58% for TN and 1–68% for TP. In addition, analyses of the correlation between removal efficiency and precipitation characteristics by pollutant type showed that particulate materials have a high correlation with nutrient materials and heavy metals, while organic materials and nutrient materials also have a high correlation. A grain-size analysis of 1–100 μm diam...

Changes in the characteristics of organic compounds depending on the nitritation efficiency

This study focused on nitritation reactions for the removal of highly concentrated nitrogen from water recycled by a MWTP (Municipal Wastewater Treatment Plant) for the preparation of effluent standards which will be strengthened. To examine the changes that occur during a nitritation reaction with a variety of SRT operations when inducing a stable nitritation reaction, a reactor was operated on a laboratory scale in this study. Digestion tank supernatant flowed into a laboratory-scale reactor and organic matter in the effluent under various operation conditions was classified into four types according to ASM standards using the test known as the OUR (Oxygen Uptake Rate)-test. Most organic matter in the digestion tank supernatant appeared to consist of mainly the SI component out of non-biodegradable organic matter. During the operation period of the effluent in the laboratory-scale reactor, if a nitritation reaction occurs in a stable manner, most biodegradable organic matter is removed, consisting of mainly the SI component, like the influent. Particularly, nitrogen was removed after the SS was removed from the organic matters. Moreover, through a multiple correlation analysis between the operation results from a laboratory-scale reaction bath and the organic composition of the effluent, a method to predict the organic composition of effluents that relies on the operation result of the effluent is proposed.

Determination of first flush criteria from an urban residential area and a transportation land-use area

Abstract This study was conducted to identify the magnitude of first flush in a city residential area and a transportation land-use area and to provide basic information related to the criteria of stormwater runoff management. Stormwater runoff was monitored at two separate urban watersheds, which were chosen to represent the distinct types of a residential area and a transportation land-use area. 25 storm events were monitored to investigate the first flush phenomena. The first flush criterion was determined by dynamic EMC and mass-first-flush ratio (MFF n ) methods. It was assessed to be 5.5 mm in the residential area and 2.8 mm in the transportation land-use area according to the MFF n method (median value). The magnitude of the first flush phenomenon was assessed to be 6.5 mm in the residential area and 6.8 m min the transportation land-use area according to dynamic EMC.

Comparison of Bio-P module and the Modified Bio-P module in the step-feed biological nutrient removal process

The Modified Bio-P module was evaluated in terms of the kinetic rate expression and engineering parameters, comparing the measured data of full-scale plant with simulated data. To simulate step-feed BNR (Biological Nutrient Removal), the ASM3 (Activated Sludge Model 3) with the EAWAG Bio-P Module (The Swiss Federal Institute for Environmental Science and Technology) and the ASM3+Modified Bio-P module were used. The RMSEs (root mean square error) of the T-N (total nitrogen) concentration of the effluent levels of measured and simulated examples were 2.29 for ASM3+Bio-P and 1.28 for ASM3+Modified Bio-P. In the case of T-P (total phosphorus), the RMSEs were 0.28 for ASM3+Bio-P and 0.25 for ASM3+Modified Bio-P. The annual removal rates for T-N were 0.77 for the measured, 0.69 for the Bio-P, and 0.74 for the Modified Bio-P samples, while the annual removal rates for T-P were 0.64 for the measured, 0.72 for the Bio-P, and 0.60 for the Modified Bio-P cases. With simulated data, the Modified Bio-P model was a better fit for the field data compared to Bio-P. The Modified Bio-P module reproduced the step-feed process more effectively than the Bio-P module.

Non-point source analysis of a railway bridge area using statistical method： Case study of a concrete road-bed

In an effort to protect the quality of the water system, interest in non-point source pollution is increasing. Recently, studies of non-point sources pollution are continuing in relation to various land-use areas, but such studies have not been fully conducted in railway facility sites. Using monitoring data of railway bridge area with concrete road-bed, the runoff characteristics, pollutant unit loads, and first flush criteria were assessed. Railway bridge area with concrete road-bed typically show the first flush effect, and the pollutant unit load was determined to be higher than other public facilities areas. Further, the first flush criteria show an effective rainfall amount of 7 mm. In other words, from the runoff of railway facilities, considerable amounts of non-point source pollutants are occurred, indicating the need to create best management practices which are adequate for railway facility sites.

Study on the applicability of the ozone / AOP and activated carbon process for the removal of trace organic contaminants and taste odor causing substances

This study was conducted to assess the removal characteristics of taste and odor causing compounds(2-MIB and geosmin) and micro organic matters. GAC and BAC process consisting of Ozone/AOP and activated carbon was applied. As a result, the influent concentration of 2-MIB 159 ng/L and geosmin 371 ng/L were removed 42% and 86% by ozone 1.0 mg/L, and 58%, 90% by AOP(ozone 1.0 mg/L + H2O2 0.5 mg/L). Also it showed less than 2 ng/L effluent in GAC process and 99.8% removal efficiency in BAC process. Therefore, BAC process combining ozone/AOP and GAC is effective for persistent removal of micro organic matters, taste and odor. It is needed for optimization of Ozone/AOP process according to influent concentrations.