Biosorption of phosphate from synthetic wastewater by biosolids

Abstract

AbstractThe aim of this study was to determine the potential of phosphate (P) removal from wastewater by biosolids prepared by the immobilization of P-accumulating bacteria onto organic bentonite. Organic bentonite was prepared by treating bentonite clay with quaternary ammonium salt — cetyltrimetylammonium (CTA) bromide. Cation exchange capacity (CEC) of the bentonite was found to be 179.0 meq/100 g of the dry bentonite. The CTA occupied ca. 175% of the CEC. Modification of bentonite with CTA in amounts higher than 55% of the CEC resulted in the change of zeta potential of particles from negative to positive. Only in reactors containing organic bentonite samples occupied with 3.5 and 28% of the CEC was P efficiently removed from wastewater by combined adsorption and bacterial uptake in the biomass. Organic bentonite samples with higher CTA loadings (from 55 to 175% of the CEC) showed bactericidal effects. To enhance P removal from wastewater in the aerated biological system, biosolids consisting of P-accumulating bacteria and organic bentonite can be used, but special attention should be given to the configuration of sorbed CTA molecules and its potential desorption.