Wyniki wyszukiwania - Biblioteka Nauki

1

Optimization of electrocoagulation of instant coffee production wastewater using the response surface methodology

100%

Bui H. M.

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2017

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tom Vol. 19, nr 2

67--71

EN

The COD removal efficiency from an instant coffee processing wastewater using electrocoagulation was investigated. For this purpose, the response surface methodology was employed, using central composing design to optimize three of the most important operating variables, i.e., electrolysis time, current density and initial pH. The results based upon statistical analysis showed that the quadratic models for COD removal were significant at very low probability value (<0.0001) and high coefficient of determination (R2 = 0.9621) value. The statistical results also indicated that all the three variables and the interaction between initial pH and electrolysis time were significant on COD abatement. The maximum predicted COD removal using the response function reached 93.3% with electrolysis time of 10 min, current density of 108.3 A/m2 and initial pH of 7.0, respectively. The removal efficiency value was agreed well with the experimental value of COD removal (90.4%) under the optimum conditions.

2

Effect of land-use changes resulting from shrimp farming on acid sulfate soils in the Can Gio coastal wetland area (Vietnam)

63%

Tran T. B. , Bui H. M.

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nr 2

EN

Acid sulfate soils in coastal wetland areas are particularly vulnerable to land-use changes. We identifid the potential impacts of land-use changes in the Can Gio coastal wetland area in Vietnam due to the reclamation of acid sulfate soils from shrimp farms. Our study applied the support of vector machine algorithm in ENVI software to observe land-use changes from 1995 to 2015, using Landsat Thematic Mapper and Operational Land Imager data. We classifid the land use of the study area into four major classes including vegetation, bare land, dedicated land and aquaculture land. Our study successfully met the overall classifiation accuracy requirement above 95% and kappa statistics above 0.95. Between 1995 and 2006, about 2,938.05 ha of bare land and 1,464.66 ha of vegetation (mangrove forest) were converted to aquaculture land. In contrast, between 2006 and 2015, 2,423.88 ha of aquaculture land converted back to bare land, mainly related to the abandonment of shrimp ponds due to crop failure and disease. The disturbance of acid sulfate soils through initial soil reclamation and subsequent fallowing is considered a key reason for hastening and extending soil acidifiation in the study area. We collected 144 topsoil samples from 17 fallowed ponds in two batches, and 142 of these were acidic: 128 samples were extremely and strongly acidic (pH < 5.5), 14 samples were moderately and slightly acid (pH between 5.5 and 6.5), and only two samples were neutral (pH over 6.5).

3

Applying an artificial neural network to predict coagulation capacity of reactive dyeing wastewater by chitosan

51%

Bui H. M. , Duong H. T. G. , Nguyen C. D.

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nr 2

EN

Chitosan derived from waste shrimp shells was experimentally evaluated to treat reactive dye (red 24) in aqueous solution. The research was conducted using one-factor-at-a-time experiment design (i.e., pH, reaction time, agitation speeds, initial dye, and chitosan concentration) to investigate dye removal effi ciencies by reducing colour and COD parameters. The results obtained by performing Jar-tests indicated that prepared chitosan successfully removed the reactive dye in aqueous solution. In particular, 99.5% of colour and 72.7% COD removal effi ciencies were recorded under neutral conditions (pH 7) with chitosan dosage 80 mg/L and agitation speed 60 rpm in 30 min. Fourier transform infrared spectra (FTIR) of the chitosan, dye, and formed sludge were also investigated to elucidate the removal mechanism of the dye by chitosan. These indicated the potential of using chitosan as a “green” coagulant to reduce pollutants of textile wastewater. Moreover, three-layer feed-forward artifi cial neural network (ANN) models were applied to model the coagulation processes with the determination coeffi cient (R2) 0.986 and the root mean square error (RMSE) 2.951 between predicted and observed outputs. The ANN models were analysed with the connection weight method, neural interpretation diagram, and 3D/contour plots to study the infl uences of operation factors – both individually and combined – on both colour removal and COD removal process.

4

Shortening the acclimation and degradation lag of xenobiotics by enriching the energy content of microbial populations

51%

Nguyen H. L. , Chong M. N. , Bui H. M.

Polish Journal of Environmental Studies

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2018

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tom 27

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nr 6

EN

We studied shortening the acclimation and enhancement of the degradation rate for a xenobiotic organic pollutant using microbial populations grown in suspension as activated sludge. Soil populations cultivated as raw activated sludge in a steady-state fed-batch reactor and the raw sludge were re-cultured (energy enriched) with biogenic substrates and compared for their performances in acclimation and degradation of 2,4-D. The cells’ mass and ATP content were also measured during the 2,4-D acclimation and degradation. The optimal concentration of supplemental biogenic substrate and most suitable time point of re-cultivation that could produce the most shortening of lag phase were determined in a previous study. The purpose of this study was to find the true mechanism of this shortening based on the contents of cell internal ATP. As compared with the raw sludge, the enriched sludge contained a higher amount of energy at the start of acclimation and brought a shortened lag time during the acclimation process. External energy (biogenic substrates’s energy) invested into activated sludge cells could improve the microorganisms in acclimation to a xenobiotic by sustaining the energy needed for the difficult xenobiotic metabolism.

5

Removal of arsenic from groundwater using lamdong laterite as a natural adsorbent

51%

Nguyen P. T. T. , Yacoube S. , Pare S. , Bui H. M.

Polish Journal of Environmental Studies

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2020

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tom 29

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nr 2

6

Combination of SAR polarimetric parameters for sstimating tropical forest aboveground biomass

45%

Tuong T. T. C. , Tani H. , Wang X. , Thang N. Q. , Bui H. M.

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nr 5

7

Lipid production combined with removal and bioaccumulation of Pb by Scenedesmus sp. green alga

38%

Pham T.-L. , Dao T.-S. , Bui H. N. , Pham T. K. N. , Ngo T. T. H. , Bui H. M.

Polish Journal of Environmental Studies

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2020

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tom 29

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nr 2