Adsorption-biodegradation of phenol by immobilized candida tropicalis retl-cr1 onto natural and modified zeolite
Phenol has been in produced since 1860s. The application of phenol and its derivatives is worldwide. However, phenol is highly toxic and able to retain in environment for a long period. Despite being toxic, C tropicalis RETL-Crl is capable of consuming phenol as their carbon sources. Remarkable perf...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2018
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| Subjects: | |
| Online Access: | https://eprints.ums.edu.my/id/eprint/38501/1/24%20PAGES.pdf https://eprints.ums.edu.my/id/eprint/38501/2/FULLTEXT.pdf |
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| Summary: | Phenol has been in produced since 1860s. The application of phenol and its derivatives is worldwide. However, phenol is highly toxic and able to retain in environment for a long period. Despite being toxic, C tropicalis RETL-Crl is capable of consuming phenol as their carbon sources. Remarkable performance in free cells systems makes C tropicalis RETL-Crl valuable to the removal of toxic pollutant like phenol. The application of natural and modified zeolite in toxic pollutant treatment is familiar. Therefore, the main goal of this research is to determine the potential of C tropicalis RETL-Crl in an immobilized system and the feasibility of natural zeolite (NZ) and surfactant modified zeolite (SMZ) as solid carrier and adsorbent in the adsorption-biodegradation of phenol. NZ is modified with the various concentration of cationic surfactant to form SMZ. The modification is confirmed by the FTIR, XRD, TGA and SEM analysis. Various parameters such adsorbent dose, particle size, initial cell loading and incubation time had been optimized for the immobilization protocol of C tropicalis RETL-Crl onto NZ and SMZ. SMZ immobilized significantly higher cells than NZ by 3.8 folds. Cells retention of 3.85x1010 CFU/g and 1.09x1010 CFU/g were obtained by SMZ and NZ respectively. Various factors influencing the phenol biodegradation by immobilized yeast cells onto NZ and SMZ is optimized and applied to two different modes of continuous phenol biodegradation; simultaneous adsorption-biodegradation and separate adsorption by NZ and SMZ then biodegradation by free cells (FC) in suspension. The removal percentages of phenol from free cells to immobilized cells were improved from 81 % to 99% in the 7mM of Phenol. This indicates that the degradation of phenol using immobilized cells is more effective than when utilizing FC. SMZ recorded 99% removal efficiency when phenol concentration is increased to 7mM with the removal rate of 26.35mg/L.hr. While the phenol biodegradation by FC and immobilized cells onto NZ shows 81 % and 75% removal. Accumulation of catechol is monitored, with maximum production of 15. 75 and 32.33 mg/L when NZ and SMZ are used, respectively. The kinetic model of phenol adsorption-biodegradation by immobilized yeast cells onto NZ and SMZ can be described by pseudo-first (physisorption) and pseudo-second (chemisorption) order respectively. An intraparticle diffusion model proves it is not the only rate controlling phase for the process. When SMZ is applied in continuous system, at the concentration of 16mM, simultaneous and separate system of adsorption-biodegradation took only 34 and 32 hours to complete the phenol removal with the removal rate of 44.29 and 47.00 mg/L.hr respectively with the maximum catechol production of 33.40mg/L for both systems. These results show significant improvement compared to previous report on phenol removal in continuous flow system. C tropicalis RETL-Crl perform better when immobilized and applicability of NZ and SMZ as the carrier matrix for phenol removal is confirmed. This study has therefore provided further substantial knowledge regarding versatility of C tropical/is RETL-Crl roles in the environment. Finally, it is possible to apply this simple and economic treatment in large scale at wastewater treatment plant containing high concentration of phenol. |
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