Bioflocculant producing bacillus megaterium from poultry slaughterhouse wastewater: elucidation of flocculation efficacy and mechanism

Abstract

The study focused on isolating bioflocculant-producing microorganisms from poultry slaughterhouse wastewater (PSW). Microorganisms (n = 20) were isolated, and the D2 isolate, identified as Bacillus megaterium using 16S rDNA and RpoD (sigma 70), had maximum flocculation activity. Furthermore, characteristics of the bioflocculant produced by B. megaterium were determined, and the optimum storage conditions, including the flocculation mechanism, were identified. The bioflocculant was composed mainly of polysaccharides and proteins and was better stored frozen in a crude form. Furthermore, the flocculation efficacy was assessed using response surface methodology at pH 4 (min) and 9 (max), bioflocculant dosage of 1% (min) and 3% (max, v/v), indicating pH 6.5 and dosage of 2% (v/v) as optimum flocculation conditions for floc formation under ambient temperature. These results were further confirmed with microscopy assessments with zeta potential measurements confirming that the bioflocculant was ionic, albeit charge neutralization was not the primary mechanism for floc agglomeration. Hydrogen bonding was predominant, indicative of a neutralization-bridging mechanism, an assertion also based on the functional groups prevalent in the isolate-B. megaterium. The results obtained indicate that bioflocculants can be used to treat isolates that are sourced from wastewater.