Abstract
The low microbial flocculant yields and efficiencies limit their industrial applications. There is a need to identify bacteria with high bioflocculant production. The aim of this study was to isolate and identify a bioflocculant-producing bacterium from activated sludge wastewater and characterise its bioflocculant activity. The identification of the isolated bacterium was performed by 16S rRNA gene sequencing analysis. The optimal medium composition (carbon and nitrogen sources, cations and inoculum size) and culture conditions (temperature, pH, shaking speed and time) were evaluated by the one-factor-at-a-time method. The morphology, functional groups, crystallinity and pyrolysis profile of the bioflocculant were analysed using scanning electron microscope (SEM), Fourier transform infrared (FTIR) and thermogravimetric (TGA) analysis. The bacterium was identified as Proteus mirabilis AB 932526.1. Its optimal medium and culture conditions were: sucrose (20 g/L), yeast extract (1.2 g/L), MnCl2 (1 g/L), pH 6, 30 °C, inoculation volume (3%), shaking speed (120 rpm) for 72 h of cultivation. SEM micrograph revealed the bioflocculant to be amorphous. FTIR analysis indicated the presence of hydroxyl, carboxyl and amino groups. The bioflocculant was completely pyrolyzed at temperatures above 800 °C. The bacterium has potential to produce bioflocculant of industrial importance.
Highlights
Water is one of the most important components of survival and thriving to carbonbased life forms [1]
The attempt to reduce the production cost of bioflocculants has been effective but not sufficient. This has led to the search for microorganisms with better bioflocculant producing capacity
The results show that wastewater from the activated sludge from the Vulindlela Wastewater Treatment Plant had 8 × 103 colony forming units per millilitre (CFU/mL) (Table 2)
Summary
Water is one of the most important components of survival and thriving to carbonbased life forms [1]. Water is polluted when compromised as the result of anthropogenic impurities, which could be agricultural, industrial and domestic wastes [2]. The consumption of polluted water has caused the increase in waterborne diseases in communities [3]. Flocculation falls among alternative physico-chemical methods of choice for the elimination of organic matter and contaminations from wastewater [4]. Its purpose is to aggregate or agglomerate dispersed fine particles together to form large flocs that are quick to sediment [4]. Flocculating agents are classified as inorganic, organic and naturally occurring flocculants, called microbial bioflocculants [1,5]
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