Identification and evaluation of bioflocculant from Bacillus salmalaya 139SI for its application in wastewater treatment / Zayed M. M. Abu Tawila

Zayed M. , M. Abu Tawila (2019) Identification and evaluation of bioflocculant from Bacillus salmalaya 139SI for its application in wastewater treatment / Zayed M. M. Abu Tawila. PhD thesis, Universiti Malaya.

	PDF (The Candidate's Agreement) Restricted to Repository staff only Download (178Kb)
	PDF (Thesis PhD) Download (2545Kb)

Abstract

Bioflocculants are flocculating compounds produced by microorganisms during their growth and has recently received extensive consideration from researchers due to their biodegradable, non-toxicity and lack of secondary pollution from degradation intermediates characteristics. The production, optimization, and Characterisation of bioflocculant QZ-7 produced by a novel Bacillus salmalaya strain 139SI which was isolated from a private farm soil in Selangor, Malaysia, were determined. Meanwhile, the optimal culture condition for bioflocculant production was achieved after cultivation at 35.5 °C for 72 h at pH 7, with an inoculum size of 5% (v/v) and sucrose, glucose as carbon source and yeast extract, urea as nitrogen sources. A bioflocculant yield of 2.72 g was recovered from 1 L of broth culture, with maximum flocculating activity that was found to be 92.6%. Chemical analysis revealed that the pure bioflocculant QZ-7 consisted of 79.08% carbohydrates and 15.68% proteins. Infrared spectrometry analysis showed the presence of carboxyl (COO-), hydroxyl (-OH), and amino (-NH3) groups, which are typically from polysaccharides and proteins. The NMR spectroscopy analysis confirmed the result of FTIR, through the presence of functional groups of the QZ-7. Scanning electron microscopy (SEM) analysis showed that QZ-7 exhibited a clear crystalline brick-shaped structure. The average molecular weight of the bioflocculant QZ-7 was calculated to be 5.13×105Da. LC-MS analysis confirmed that QZ-7 was a glycoprotein compound detected at 741m/z–745m/z. Moreover, the presence of glucose at 182.96 m/z, rhamnose at 354.3m/z, and glucuronic acid at 212.8 m/z. SEM- EDX analysis indicated the existence of C, O, N, P and S in this macromolecule as 55.74%, 42.74%, 0.54%, 0.93% iv and 0.06%, respectively. Thermogravimetric analysis (TGA) of the bioflocculant QZ-7 contained thermos-stable and thermo-labile molecules. Bioflocculant QZ-7 exhibited wide pH stability that ranged from 4 to 7, with a flocculation activity of more than 70%. In addition, QZ-7 was thermally stable and retained more than 80% of its flocculating efficiency after being heated at 60 °C for 30 min. The highest bioflocculating activity of 93.6% was obtained for Ca+2 at 2 mg/L of QZ-7 concentration at pH 7. The treatment of river water by purified bioflocculant QZ-7 showed high performance in the removal of turbidity, total suspended solids and COD. After treating the wastewater, the bioflocculant QZ-7 showed significant flocculating performance with a COD removal efficiency of 93%, whereas a BOD removal efficiency of 92.4% was observed in the B. salmalaya strain 139SI. In addition, results for the removal of heavy metals from industrial wastewater revealed that the bioflocculant QZ-7 was capable of removing the heavy metals. For example, the maximum adsorption of As (89.8 %), and Zn+2 (77.4 %), and Cu+2 (58.4%). Moreover, the bioflocculant QZ-7 had significant removal efficiency of different pharmaceutical compounds, such as Simvastatin (92.45%), Salbutamol (88.69%), Acetaminophen (69%), and Caffeine (66.52%). Furthermore, B. salmalaya 139SI strain and pure bioflocculant QZ-7 could synthesise AgNPs. Also, an antibacterial activity of the AgNPs was detected against test bacterial strains, such as Escherichia coli ATCC35401, Salmonella enteritidis ATCCBAA-711, Staphylococcus aureus ATCC2592 and Pseudomonas aeruginosa, as application of AgNPs.

Actions (For repository staff only : Login required)