Selective immobilization of Acinetobacter junii on the natural zeolitized tuff in municipal wastewater

The immobilization of desired bacteria onto material was usually performed in synthetic media. The aim of this study was to test the immobilization of phosphate (P)-accumulating bacteria Acinetobacter junii onto natural zeolitized tuff (NZ) in the raw or sterilized municipal wastewater containing the common bacteria Escherichia coli and Enterococcus faecalis and the performance of immobilized A. junii in the same type of wastewater. In the sterilized wastewater which contained the mixture of A. junii, E. coli and E. faecalis, the A. junii was selectively immobilized onto NZ in significantly higher numbers than E. coli and E. faecalis. The A. junii added in the form of bioparticles to the wastewater containing E. coli and E. faecalis, multiplied and removed P from wastewater. The P removal from wastewater was a function of biomass of P-accumulating bacteria and not the amount of NZ or bioparticles used. The performance of A. junii was significantly better in membrane filtered than in autoclaved wastewater. The experiments that were performed in raw non sterilized wastewater showed that A. junii can be successfully immobilized onto NZ in competition with natively present heterotrophic bacteria, retain its metabolic activity and successfully remove P from such water, which makes this technology feasible from biotechnological aspect.

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• In the municipal wastewater which contained the mixture of Acinetobacter junii, Escherichia coli and Enterococcus faecalis, the A. junii was selectively immobilized onto natural zeolite in 10- to 1000-fold higher numbers than E. coli and E. faecalis.
• The A. junii added in the form of bioparticles to the wastewater containing E. coli and E. faecalis, multiplied and successfully removed P from wastewater.
• The immobilization of P-accumulating bacteria A. junii onto natural zeolite can be performed in raw, non-sterile real wastewater which is important from biotechnological point of view.