• Nano
• /
• 제13권11호
• /
• pp.1850127.1-1850127.13
• /
• 2018

Bi metal deposited on $Bi_2MoO_6$ composite photocatalysts have been successfully synthesized via a simple reduction method at room temperature with using $NaBH_4$ as the reducing agent. The photocatalytic activity of the composite was evaluated by degradation of rhodamine B (RhB) and bisphenol A (BPA) solution under visible light. The rate constant of $Bi/Bi_2MoO_6$ composite to RhB is 10.8 times that of $Bi_2MoO_6$, and the degradation rate constant of BPA is 6.9 times of that of $Bi_2MoO_6$. Nitrogen absorption-desorption isotherm proved that the increase of specific surface area is one of the reasons for the improvement of photocatalytic degradation activity of $Bi/Bi_2MoO_6$ composites. The higher charge transfer efficiency of $Bi/Bi_2MoO_6$ is found through the characterization of the photocurrent and impedance, which are attributed to the surface plasmon resonance (SPR) effect produced by the introduction of the metal Bi monomer in the composite. Free radical capture experiments proved that cavitation is the main active species. Based on the above conclusions, a possible mechanism of photocatalytic degradation is proposed.

• 한국초전도ㆍ저온공학회논문지
• /
• 제25권3호
• /
• pp.7-12
• /
• 2023

Isolation of pollutant-degrading bacteria is important in bioaugmentation, one of the methods for biological degradation of environmental contaminants. We focused on the magnetic activated sludge (MAS) process as a culture method that efficiently concentrates degrading bacteria, and cultured activated sludge with 1,4-dioxane as a model pollutant. After 860 days of operation, MLVSS, which indicates the amount of sludge, increased from 390 mg/L to 10,000 mg/L, and the removal rate of organic matter including 1,4-dioxane, tetrahydrofuran, and glucose in the artificial wastewater reached up to 97%. Based on these results, the MAS process was successfully used to acclimate activated sludge with 1,4-dioxane. Bacterial flora analysis in the MAS showed that bacteria of the genus Pseudonocardia, already reported as 1,4-dioxane degrading bacteria, play an important role in the degradation of this pollutant. The MAS process is a suitable culture method for acclimation of environmental pollutants, and the findings indicate that it can be used as an enrichment unit for pollutant-degrading bacteria.

• 한국환경보건학회지
• /
• 제20권3호
• /
• pp.78-84
• /
• 1994

The effects of heavy metal, Cd on the degradation of the herbicide butachlor (N-Butoxymethyl-2-chlor-2',6'-diethylacetanilide) in soils were examined the laboratory. The degradation of the herbicide in soil was greatly inhibited by the amendment of the heavy metal, Cd. The inhibited rate of Cd concentration was high in the order of 30 ppm>20 ppm> 10 ppm>0 ppm. And tile degradation rate of butachlor was high in order of 80 $\mu$M>40 $\mu$M>20 $\mu$M. The effects of Cd on the degradation of the butachlor in soil varied with concentration of heavy metal and butachlor.

• Environmental Engineering Research
• /
• 제24권2호
• /
• pp.318-323
• /
• 2019

Paper focuses on comparison between two different orifice plate configurations (plate number 1 and plate number 2) used as cavitating device in the hydrodynamic cavitation reactor for improving pollutant removal efficiencies. Effect of four different parameters such as hydraulic characteristics (in terms of range of flow rates, orifice velocities, cavitation number at different inlet pressures); cavitation number (in range of 5.76-0.35 for plate number 1 and 1.20-0.35 for plate number 2); inlet pressure (2-8 bars) and reaction time (0 to 60 min) in terms of chemical oxygen demand (COD) removal and chlorpyrifos degradation has been studied and compared. Optimum inlet pressure of 5 bars exists for degradation of pollutants for both the plates. It is found that geometry of orifice plate plays important role in removal efficiencies of pollutant. Results obtained confirmed that orifice plate 1 with configuration of 1.5 mm 17 holes; cavitational number of 1.54 performed better with around 60% COD and 98% chlorpyrifos removal as compared to orifice plate 2 having configuration of 2 mm single hole; cavitational number of 0.53 with 40% COD and 96% chlorpyrifos in 2 h duration time.

• 공업화학
• /
• 제32권3호
• /
• pp.340-347
• /
• 2021

The aim of this research is to assess the use of high purity potassium ferrate (VI) for the efficient removal of sulfamethoxazole (SMX), one of the potential micro-pollutant found in aqueous waste. In addition, various parametric studies have enabled us to deduce the mechanism in the degradation process. The pH and concentration of sulfamethoxazole enable the degradation of pollutants. Moreover, the time-dependent degradation nature of sulfamethoxazole showed that the degradation of ferrate (VI) in presence of sulfamethoxazole followed the pseudo-second order kinetics and the value of rate constant increased with an increase in the SMX concentration. The stoichiometry of SMX and ferrate (VI) was found to be 2 : 1 and the overall rate constant was estimated to be 4559 L²/mmol²/min. On the other hand, the increase in pH from 8.0 to 5.0 had catalyzed the degradation of SMX. Similarly, a significant percentage in mineralization of SMX increased with a decrease in pH and concentration. The presence of co-existing ions and SMS spiked real water samples was extensively analyzed in the removal of SMX using ferrate (VI) to simulate studies on real matrix implication of ferrate (VI) technology.

• Environmental Engineering Research
• /
• 제20권1호
• /
• pp.89-97
• /
• 2015

Remediation of wastewater contaminated with metal(II)-complexed species (Cu(II)-NTA (NTA: nitrilotriacetic acid), Cu(II)-EDTA (EDTA: ethylenediamine tetraacetic acid) and Cd(II)-EDTA is attempted using the potential applicability of ferrate(VI). Kinetics of pollutant degradation is obtained with the removal of ferrate(VI) studied at wide range of pH (8.0-10.0) and the concentration of metal(II)-complexed species (0.3 to 15.0 mmol/L) employing a constant dose of ferrate(VI) i.e., 1.0 mmol/L. Pseudo-first-order and pseudo-second-order rate constants were obtained in the reduction of ferrate(VI) which was then employed to obtain the overall rate constants of the pollutant degradation. The mineralization of NTA and EDTA was obtained with the change in TOC (total organic carbon) values collected by the ferrate(VI) treated pollutant samples. Decrease in pH and molar pollutant concentrations was greatly favored the percent mineralization of NTA or EDTA by the ferrate(VI) treatment. The treated pollutant samples were filtered and subjected for AAS (atomic absorption spectrophotometric) analysis to assess the simultaneous removal of copper and cadmium from aqueous solutions at the studied pH as well at the elevated pH 12.0. Results show that an enhanced removal of cadmium or copper was achieved at pH 12.0. Overall, ferrate(VI) possesses multifunctional application in wastewater treatment as it oxidizes the degradable impurities and removes metallic impurities by coagulation process.

• Journal of Microbiology and Biotechnology
• /
• 제19권9호
• /
• pp.1028-1033
• /
• 2009

In this study, the dynamics of living cells (LC) and dead cells (DC) in a laboratory-scale biofilm membrane bioreactor for waste gas treatment was examined. Toluene was used as a model pollutant. The bacterial cells were enumerated as fluoromicroscopic counts during a 140 operating day period using BacLight nucleic acid staining in combination with epifluorescence and confocal laser scanning microscopy (CSLM). Overall, five different phases could be distinguished during the biofilm development: (A) cell attachment, (B) pollutant limitation, (C) biofilm establishment and colonization, (D) colonized biofilm, and (E) biofilm erosion. The bioreactor was operated under different conditions by applying different pollutant concentrations. An optimum toluene removal of 89% was observed at a loading rate of 14.4 kg $m^{-3}d^{-1}$. A direct correlation between the biodegradation rate of the reactor and the dynamics of biofilm development could be demonstrated. This study shows the first description of biofilm development during gaseous toluene degradation in MBR.

• Journal of Microbiology and Biotechnology
• /
• 제16권11호
• /
• pp.1819-1825
• /
• 2006

Four naphthalene-degrading bacteria (Pseudomonas sp. strains O1, W1, As1, and G1) were isolated feom pollutant-contaminated sites. Examination of their substrate utilization and analyses of key naphthalene-catabolic regulatory genes revealed that the pathway and regulation of naphthalene-degradation in all four strains resemble those of NAH7 from P. putida G7. Superoxide anion production, superoxide dismutase activity, and catalase activity during their growth on naphthalene-amended medium increased significantly, compared with those with glucose-amended medium. Addition of ascorbate, an antioxidant, or ferrous iron ($Fe^{2+}$) increased the growth rates of all tested microorganisms on naphthalene. Northern blot and HPLC analyses showed that both nahA gene expression and naphthalene degradation increased under those conditions. Our data suggest that naphthalene degradation can impose severe oxidative stress, and defenses against oxidative stress would play an important role in the metabolism of naphthalene.

• 한국물환경학회지
• /
• 제24권5호
• /
• pp.543-549
• /
• 2008

Human activities and land-use practices are intensely widening the urban areas. High impervious surface areas cover much of urban landscapes and are the primary pollutant sources which can lead to water quality and habitat degradation in its watershed. As the urban areas expand, transportation land-use such as parking lots, roads, service areas, toll-gates in highways and bridges also increase. These land-uses are significant in urban pollution due to high imperviousness rate and vehicular activities. To regulate the environmental impacts and to improve the water quality of rivers and lakes, the Ministry of Environment (MOE) in Korea developed the Total Pollution Load Management System (TPLMS) program. The main objective is to lead the watershed for a low impact development. On a local scale, some urban land surfaces can be emitting more pollution than others. Consequently, in urban areas, the unit loads are commonly employed to estimate total pollutant loadings emitted from various land-uses including residential, commercial, industrial, transportation, open lands such as parks and golf courses, and other developed land like parking areas as a result of development. In this research, unit pollutant loads derived specifically from transportation land-uses (i.e. branched out from urban areas) will be provided. Monitoring was conducted over 56 storm events at nine monitoring locations during three years. Results for the unit pollutant loads of transportation land-use are determined to be $399.5kg/km^2-day$ for TSS, $12.3kg/km^2-day$ for TN and $2.46kg/km^2-day$ for TP. The values are higher than those of urban areas in Korean MOE and US highways. These results can be used by MOE to separate the pollutant unit load of transportation landuses from urban areas.

• Journal of Microbiology and Biotechnology
• /
• 제23권11호
• /
• pp.1610-1616
• /
• 2013

Endosulfan is a chlorinated pesticide; its persistence in the environment and toxic effects on biota are demanding its removal. This study aims at improving the tolerance of the previously isolated fungus Aspergillus niger (A. niger) ARIFCC 1053 to endosulfan. Released chloride, dehalogenase activity, and released proteins were estimated along with analysis of endosulfan degradation and pathway identification. The culture could tolerate 1,000 mg/ml of technical grade endosulfan. Complete disappearance of endosulfan was seen after 168 h of incubation. The degradation study could easily be correlated with increase in released chlorides, dehalogenase activity and protein released. Comparative infrared spectral analysis suggested that the molecule of endosulfan was degraded efficiently by A. niger ARIFCC 1053. Obtained mass ion values by GC-MS suggested a hypothetical pathway during endosulfan degradation by A. niger ARIFCC 1053. All these results provide a basis for the development of bioremediation strategies to remediate the pollutant under study in the environment.