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Dr 

Ntombela, Zuzingcebo

Faculty: Faculty of Science, Agriculture and Engineering
Department: Biochemistry and Microbiology
Research Interest(s): Bioflocculant technology, Green nanotechnology, Wastewater treatment, Microbial biotechnology, Sustainable water purification solutions, Applied environmental microbiology.
Biography: Dr Z.G. Ntombela is a lecturer in the field of Microbiology at the University of Zululand at Kwa-Dlangezwa Campus. He holds a PhD. degree in Microbiology. His research interests are wastewater purification using biological methods and nanotechnology. He has published over 15 peer reviewed manuscripts. He has successfully supervised/ co-supervised seven MSc and one PhD students. He is currently supervising/ co-supervising eight postgraduate (Honours, MSc and PhD) students.
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20222

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    Production and characterization of a bioflocculant from Pichia kudriavzevii MH545928.1 and its application in wastewater treatment
    2022
     | MDPI
    A variety of flocculants have been used to aggregate colloidal substances. However, recently, owing to the adverse effects and high costs of conventional flocculants, natural flocculants such as microbial flocculants are gaining attention. The aim of the study was to produce and characterize a bioflocculant from Pichia kudriavzevii MH545928.1 and apply it in wastewater treatment. A mixture of butanol and chloroform (5:2 v/v) was used to extract the bioflocculant. Phenol–sulphuric acid, Bradford and Carbazole assays were utilized for the identification of carbohydrates, proteins and uronic acid, respectively. Scanning electron microscopy (SEM) and elemental detector were employed to determine the surface morphology and elemental compositions. The removal efficiencies were 73%, 49% and 47% for BOD, COD and P, respectively. The bioflocculant (2.836 g/L) obtained showed the presence of carbohydrates (69%), protein (11%) and uronic acid (16%). The bioflocculant displayed a cumulus-like structure and the elemental composition of C (16.92%), N (1.03%), O (43:76%), Na (0.18%), Mg (0.40%), Al (0.80%), P (14.44%), S (1.48%), Cl (0.31%), K (0.34%) and Ca (20.35). It showed the removal efficiencies of 43% (COD), 64% (BOD), 73% (P) and 50% (N) in coal mine wastewater. This bioflocculant is potentially viable to be used in wastewater treatment.
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    Biosafety, optimization and application of bioflocculant-synthesized zinc oxide nanoparticle
    2022
     | Springer Nature
    Biosynthesis of zinc oxide (ZnO) nanoparticles using natural products seems to be an interesting research to study in nanotechnology, as they (ZnO nanoparticles) are biocompatible and stable in nature, owing to their wide applications industrially. In this study, the bioflocculant-synthesized zinc oxide nanoparticles were used in the removal of various pollutants and dyes from wastewater and solutions. ZnO nanoparticles were synthesized using a bioflocculant from two bacteria and assessed for flocculation and antimicrobial activity properties. Cytotoxicity effects of the ZnO nanoparticles were also evaluated using human embryonic kidney (HEK 293) and breast cancer (MFC 7) cell lines. Biosynthesized ZnO nanoparticles were characterized using different spectroscopic and microscopic methods. An optimum flocculating activity (88%) was obtained with 0.2 mg/mL ZnO nanoparticles concentration at pH 3 and LiCl as a stimulating agent. Biosynthesized ZnO nanoparticles are thermally stable with 75% flocculating activity retained at 100 °C and 71% after autoclaved (121 °C for 15 min). The as-synthesized nanoparticles showed significant cytotoxic effects in HEK 293 and MFC 7 cell lines in a concentrationdependent manner. Biosynthesized ZnO nanoparticles revealed strong antimicrobial potential on both Gram-positive and Gram-negative pathogenic bacteria tested. The nanoparticles exhibited dye removal efficiency greater than 89% of all tested dyes. ZnO nanoparticles showed great removal efficiencies of various pollutants in wastewater. Biosynthesized ZnO nanoparticles have great potential to remove both biological oxygen demand (BOD) and chemical oxygen demand (COD) compared to traditional flocculants. Therefore, as-synthesized ZnO nanoparticles have prospective to replace chemical flocculants in the purification of industrial wastewater.
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