WoodenLeg: Reducing Legionella in pulp- and paper-mill wastewater treatment

Paper and pulp mills (PPM) use large quantities of water to produce paper from wood, up to 70 m3 per m3 of paper.

Biological treatment plants (BTP) are commonly used to remove organic compounds from process water of such mills, thereby lowering the risk of pollution and eutrophication of downstream recipients.

Despite a crucial role for the functioning of such BTP plants, its microbiomes have barely been studied, which is noteworthy, not least since they can host pathogenic Legionella (up to 107 CFU/ml), representing a severe risk of infection for workers and neighbors.

Here, we want to understand the biotic interactions taking place in the BTP, with a particular emphasis on their impact on Legionella growth.

We will survey the variation in microbiome composition in different BTPs using amplicon sequencing and shotgun metagenomics to follow microbiome variation over time and between different parts of the BTPs. We will then extend the study to allall PPM in Sweden, with a particular focus on Legionella and protists.

Using co-occurrence network analyses, we will establish predictors for the resilience of the microbiome and for increased abundance of Legionella.

This study should (i) identify factors and microorganisms enhancing or preventing Legionella growth in BTPs, (ii) contribute a simple, inexpensive routine method to monitor the microbiome; (iii) contribute to a better understanding of the BTP process to improve its design and operation.