Isolation, identification and selection of bacteria with the proof-of-concept for bioaugmentation of whitewater from woodfree paper mills

Abstract

AbstractWhen whitewater circuits in the paper industry are closed, organic compounds accumulate and cause adverse production problems, such as the formation of slime and pitch. Since wood-free whitewater is usually a mixture of additives for paper production and an efficient cost-effective purification technology for their removal is lacking, the aim of our study was to find an effective bio-based strategy for whitewater treatment using a selection of indigenous bacterial isolates. We first obtained a large collection of bacterial isolates and then tested them individually for their ability to degrade the organic additives used in papermaking, i.e. carbohydrates, resin acids, alkyl ketene dimers, polyvinyl alcohol, latex, and azo and fluorescent dyes. Out of the 355 bacterial isolates, we selected a combination of four strains (Xanthomonadales bacterium sp. CST37-CF, Sphingomonas sp. BLA14-CF, Cellulosimicrobium sp. AKD4-BF and Aeromonas sp. RES19-BTP), which cover the entire spectrum of the tested organic additives. A proof-of-concept study in pilot scale was then performed by immobilizing the cells of our artificial bacterial consortium in a 33-liter tubular flow-through reactor with a retention time of <15 h. The combination of the four native strains enabled an 88% reduction in COD of whitewater even after 21 days. Additionally, we show that the bio-based whitewater treatment surpasses photolysis and photocatalysis.Graphical abstractHighlightsA strategy for selecting a consortium of indigenous bacteria with a high potential for bioaugmentation of wood-free whitewater is presented.Study of bacterial degradation of eight chemically diverse substances used in paper production is presented. Methods for the selection of bacteria suitable for industrial application were developed.The constructed artificial bacterial consortium consisted of strains belonging to genera Xanthomonadales bacterium, Sphingomonas, Aeromonas and Cellulosimicrobium.The proof of concept of the industrial application, consisting of a 33-L-column filled with the immobilized artificial consortium, was an 88% decrease in COD of the whitewater effluent.