Adsorption and biodegradation of commercial dyes using chemically-modified empty fruit bunch biochar assisted by bacteria
The aim of this study was to investigate the adsorption capacity of activated empty fruit bunch biochar (EFBB) in removing commercial dyes (methylene blue and direct red 80) assisted by dye degrading bacteria. Empty fruit bunch (EFB) is one of the wastes that has been produced from oil palm indus...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2021
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/104471/1/SARMILA%20AP%20GUNASEKARAN%20-%20IR.pdf |
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| Summary: | The aim of this study was to investigate the adsorption capacity of activated
empty fruit bunch biochar (EFBB) in removing commercial dyes (methylene blue
and direct red 80) assisted by dye degrading bacteria. Empty fruit bunch (EFB)
is one of the wastes that has been produced from oil palm industry and it can be
utilised by converting them into biochar and use them as potential adsorbent of
contaminants. Raw biochar usually possesses lower adsorption capacity.
Therefore, activation of EFBB was required to increase its surface area, porosity
and surface functional groups and consequently enhancing their adsorption
capacity. In this study, EFBBs were modified chemically by treating them with
sulphuric acid (H2SO4), potassium hydroxide (KOH) and by iron impregnation
(FeCl3). The acid coated biochar was known as A-EFBB, alkali coated biochar
as B-EFBB and Iron coated biochar as Fe-EFBB. These adsorbents were used
to remove cationic dye, methylene blue (MB) and anionic dye, direct red 80 (DR
80) at various initial concentration and their adsorption capacity was compared.
The Langmuir model fitted the isotherm data better than the Freundlich’s model
which indicated that adsorption was homogeneous and monolayer. Results for
MB showed higher adsorption capacity in the order of A-EFBB (125 mg/g) > BEFBB
(76.336 mg/g) > Fe-EFBB (10.130 mg/g) > EFBB (6.139 mg/g). While for
Direct Red 80 results showed higher adsorption capacity in the order of B-EFBB
(78.125 mg/g) > A-EFBB (40.160 mg/g) > Fe-EFBB (4.708 mg/g) > EFBB (1.150
mg/g). Apart from adsorption, biological treatments which are cost-effective and
environmentally friendly techniques, have been also widely used for many years,
but there are only a limited number of microorganisms that can degrade
contaminants at high concentrations. Hence to make use of both adsorption and
biological treatment techniques, a hybrid treatment which combined the two
treatment processes was introduced in the removal of high concentration of dyes
from wastewater. Pollutants can be removed efficiently and completely using this
new strategy. Therefore, biodegradation was tested on MB which is being widely
used in dye industry at various initial concentrations and mixed bacterial culture
was able to remove MB (100 mg/L) efficiently at 94.6% in 24 hours. The
dominant bacterial orders present in the mixed culture were identified as
Sphingomonadales followed by Pseudomonadales, Betaproteobacteriales,
Micrococcales, Clostridiales, Bacillales and others. The highest decolourisation
percentage was observed at 100 mg/L (94.60%), but the values were lower at
higher concentrations. At the highest MB dye concentration (400 mg/L), the
decolourisation percentage was the lowest (56.30%). The highly efficient
combined treatment was able to remove MB at 99.2% within 24 hours. In
nutshell, the highest percentage of MB dye decolourization was observed to be
76.5% by A-EFBB, 94.6% by mixed culture bacteria, and 99.2% by the mixed
culture bacteria immobilized on A-EFBB at 100 ppm in 24 hours. The combined
treatment has thus been proved to be an efficient way to remove dyes from
wastewater compared to the individual adsorption and biodegradation process. |
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