E.N. Hidayah; W.L. Lai; O.H. Cahyonugroho; F. Rizqa
Abstract
A combination of high performance size exclusion chromatography with organic carbon detector and ultraviolet detector coupled with peak-fitting technique and fluorescence excitation-emission matrix spectrometry applied fluorescence regional integration method was conducted to determine the characteristics ...
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A combination of high performance size exclusion chromatography with organic carbon detector and ultraviolet detector coupled with peak-fitting technique and fluorescence excitation-emission matrix spectrometry applied fluorescence regional integration method was conducted to determine the characteristics of organic matter during nitrification. The batch scale of bionet nitrification without organic carbon substrate under aerobic conditions was operated for around 150 minutes. Bulk organic parameters and NH4+-N concentration were analyzed. Five different molecular weights of organic matter were identified by using chromatography, and five different groups of fluorophores organic fractions detected by fluorescence. According to chromatography with carbon and ultraviolet detector, the main characteristics of organic matter shifted from building blocks aromatic compounds with percentage peak area of carbon/ultraviolet detector: 31%/53% to 14%/27.5% to humic-like substances with percentage peak area of carbon/ultraviolet detector 21%/17% to 27%/46.5% during nitrification. Those former compounds are biodegradable as well as properties of microbial products released during substrate utilization and endogenous phase, which are mainly identified as humic-like substances, thus underwent further biodegradation. However, there was significant change in the fluorophores organic fractions, which exhibited humic acid-like with percentage fluorescence regional index area 53% into 68%, as shown by fluorescence excitation-emission matrix analysis. A combination of these methods indicated that the organic matter released during nitrification mainly consists of humic compounds. These results conjecture that a combination of high performance size exclusion chromatography with carbon and ultraviolet detector and fluorescence excitation-emission matrix can be used to determine the characteristic of organic matter and water quality change during nitrification.
H.D. Tran; H.M.T. Vi; H.T.T. Dang; R.M. Narbaitz
Abstract
Constructed wetlands have not been commonly used in Vietnam due to the lack of information in the selection of proper types of constructed wetlands, type of reeds, design parameters and performance efficiency, in tropical climates. This paper focuses on Canna generalis, which is a common reed and easy ...
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Constructed wetlands have not been commonly used in Vietnam due to the lack of information in the selection of proper types of constructed wetlands, type of reeds, design parameters and performance efficiency, in tropical climates. This paper focuses on Canna generalis, which is a common reed and easy to grow both in water and wet land conditions. Two kinds of hybrid constructed wetlands were employed, including Facultative pond combined with free water sub-surface constructed wetlands system and horizontal subsurface flow combined with Aerobic pond system. It was found that the ponds played an important role in the hybrid system performance and enhanced the performance of constructed wetlands. The pollutant removal efficiencies of the hybrid systems were all higher than the single constructed wetlands. The BOD5, TSS, NH4-N and PO4-P removal efficiencies averaged 81%, 85%, 93% and 77%, respectively for the hybrid horizontal subsurface flow constructed wetlands system operated at a hydraulic loading rate of 0.075 m/day, while they were 89%, 97%, 97%, and 68%, respectively for the hybrid free water sub-surface constructed wetlands system operated at a hydraulic loading rate of 0.1 m/day. The removal rate constants (kBOD5, kNH4-N, kPO4-P) of the experimental hybrid constructed wetlands were similar to those in previous studies. However, these constants were higher for the hybrid free water subsurface constructed wetlands because of the modified structure flow of the free water subsurface constructed wetlands applied in this study, compared to conventional ones, as well as the additional benefits of the ponds in the hybrid systems.
B. Rahimi; A. Ebrahimi; N. Mansouri; N. Hosseini
Abstract
In this study, the photocatalytic degradation of azo-dye acid orange 10 was investigated using titanium dioxide catalyst suspension, irradiation with ultraviolet-C lamp and bismuth vanadate under visible light of light-emitting diode lamp. Response surface methodology was successfully employed to optimize ...
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In this study, the photocatalytic degradation of azo-dye acid orange 10 was investigated using titanium dioxide catalyst suspension, irradiation with ultraviolet-C lamp and bismuth vanadate under visible light of light-emitting diode lamp. Response surface methodology was successfully employed to optimize the treatment of acid orange 10 dye and assess the interactive terms of four factors. The characteristics of catalysts were determined by field emission scanning electron microscopes, X-ray diffraction and Fourier transform infrared spectroscopy. The optimum values of initial dye concentration, initial pH, irradiation time and catalyst dose were found 11.889 mg/L, 4.592, 12.87 min, and 0.178 g/100 mL for ultraviolet/titanium dioxide process, respectively, and 10.919 mg/L, 3.231, 320.26 min and 0.239 g/100 mL for visible/bismuth vanadate process, respectively. The removal efficiencies obtained for acid orange 10 were 100% and 36.93% after selecting the optimized operational parameters achieved for titanium dioxide and bismuth vanadate, respectively. The highest efficiency was achieved by the use of ultraviolet/titanium dioxide system, while a low acid orange 10 removal efficiency was obtained for the synthesized bismuth vanadate using the co-precipitation method. Thus, it seems necessary to increase the photocatalytic activity of bismuth vanadate in combination with titanium dioxide to remove acid orange 10 dye in subsequent studies.
M.R. Sabour; A. Amiri
Abstract
Fenton process, as one of the most conventional advanced oxidation processes, is widely used in the treatment of specific wastewaters, especially landfill leachate. In current study, the main target was to evaluate some neglected aspects of Fenton process in operational applications. Thus, three novel ...
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Fenton process, as one of the most conventional advanced oxidation processes, is widely used in the treatment of specific wastewaters, especially landfill leachate. In current study, the main target was to evaluate some neglected aspects of Fenton process in operational applications. Thus, three novel responses were introduced. Mass removal efficiency evaluates overall recalcitrant destruction by establishing organics mass balance pre- and post-Fenton treatment. This differentiates it from conventional chemical oxygen demand removal, since mass removal efficiency basically considers the whole mixture and not only the supernatant. The mass content ratio response provides a measure to evaluate the remaining organics in the sludge. Therefore, a borderline mode considering these limitations leads to best feasible field operations. It was found that mass content ratio for effluent reacted conversely to the sludge in response to coagulation. By increasing the coagulant dosage, coagulation improved and the sludge ratio increased in result. For the mass removal efficiency response, it seemed that appropriate balance of the oxidation/coagulation had considerable role through Fe2+ dosage and [H2O2]/[Fe2+] ratio. Finally, by including further conventional parameters such as sludge quantity, the best operational conditions (X1 = 5.7, X2 = 16, X3 = 207 mM) were optimized by response surface methodology to 27.4% and 14.4% for sludge and effluent mass content ratio, respectively, and 58.1% for mass removal efficiency. The results were in good agreement with determination coefficient (R2) of 0.94–0.97, prediction R2 of 0.80–0.93 and coefficient of variation less than 10.