engleski

Perlite and sepiolite - novel materials for immobilization of phosphate-accumulating bacteria in wastewater treatment

Technology of bacterial immobilization could be an alternative for improvement of biological phosphate removal from the wastewater. Immobilization of phosphate accumulating bacteria on suitable carriers offers higher density of bacterial cells and enhanced metabolic activity of desired bacteria in the bioreactors. In addition, immobilized bacteria are better adapted to survive periods of environmental stresses characteristic for wastewater treatment. The perlite, an expanded volcanic rock, and sepiolite, a naturally occurring clay mineral, were tested as carriers of phosphate-accumulating bacterium Acinetobacter junii. All three forms of tested perlite (non-expanded, semi-expanded and expanded) and both forms of tested sepiolite (original and purified) proved to be good carriers of A. junii. Highest number of immobilized bacteria was on the expanded perlite (12.65 × 109 CFU g-1) followed by semi expanded (5.57 × 109 CFU g-1) and non-expanded (1.68× 109 CFU g-1) perlite. The numbers of bacteria immobilized on sepiolite were 8.12 ×109 CFU g-1 on purified form and 5.57 × 109 CFU g-1 on original form of sepiolite. The immobilized bacteria were metabolically active and successfully removed phosphate from the simulative wastewater when incubated in pure culture or in bioaugmented activated sludge. Out of three perlite samples, the semi-expanded perlite proved to be the best carrier of A. junii in the activated sludge system due to good incorporation in the sludge. The expanded and raw perlite were, respectively, bulking and sinking in the bioreactors, thus diminishing the exposure and phosphate removal of immobilized bacteria in the wastewater. The addition of sepiolite with immobilized A. junii in activated sludge system resulted in significant improvement of phosphate removal from the wastewater, increase of biomass and better settling properties of sludge.

bacteria; immobilization; perlite; phosphate; sepiolite; wastewater

nije evidentirano