Full Length Research Paper

Turbidity and microbial load removal from river water using bioflocculants from indigenous bacteria isolated from wastewater in South Africa

Buthelezi, S. P., Olaniran, A. O.* and Pillay, B.

Discipline of Microbiology, School of Biochemistry, Genetics and Microbiology, Faculty of Science and Agriculture, University of KwaZulu-Natal (Westville Campus), Private Bag X54001, Durban 4000, Republic of South Africa.

*Corresponding author. E-mail: olanirana@ukzn.ac.za. Tel: + 27 31 260 7400.

Fax: + 27 31 260 7809.

Accepted 8 April, 2009

   Abstract

Several serious problems associated with the use of aluminum salts as coagulants in water and wastewater treatment, including Alzheimer’s disease and related health problems have necessitated the need for alternative cost effective and more environmentally acceptable coagulants. The objective of this study, therefore, was to evaluate river water turbidity and microbial load removal by bacterial bioflocculants. Turbidity removal rate ranging from 84.07 – 93.56% at 10 ppm bioflocculant concentration was obtained for all the bacterial isolates with up to 94.60% total bacterial load removal. The bioflocculants were also able to remove both Gram positive (Staphylococcus aureus and Streptococcus faecalis) and Gram-negative (Escherichia coli and Klebsiella oxytoca) bacteria used to individually spike the autoclaved river water samples, leading to complete removal of S. aureus, K. oxytoca and E. coli and up to 98.35% removal of S. faecalis in some cases. The flocculating activities (OD^-1) of the bacterial bioflocculants ranged between 47.9 - 161.02, 97.82 - 291.82, 138.89 - 443.45, and 106.11 - 710.88 in the river water spiked with S. faecalis, S. aureus, K. oxytoca and E. coli, respectively. Results from this study have indicated that the application of bacterial bioflocculants is a promising alternative to alum in the treatment of contaminated river water.

Key words: Alum, bioflocculant, flocculation, river water; turbidity.