Across the expansion of microbiological science and water engineering, calls have been emitted to better integrate microbial ecology and environmental biotechnology. Although bridging efforts have been made, the two fields specialized dramatically via new-generation analytical, technological, and numerical methods.

Water engineering entails process intensification and integration, computational fluid dynamics, sewer and plant-wide mathematical modelling. Wastewater treatment moves from conventional activated sludge to intensified technologies using biofilms and granular sludge for water and resource recovery. Water authorities develop active programs to elucidate the emission, fate and impact of chemical and biological contaminants that emerged like micropollutants and xenobiotics, antimicrobial resistances and pathogens across urban water cycles. Data are translated for chemical and microbial risk assessments to support the upgrade of water quality regulations and sanitation technical measures. The biological stability of drinking water is investigated from surface and ground water sources to treatment, network, household hoses, and tap.

Unprecedented wet-lab and dry-lab analytical progress in microbial ecology help crack complex microbial and metabolic puzzles across water systems. Systems microbiology establishes with genome-centric metagenomics, high-throughput multi-omics, and high-sensitivity ecophysiology to elucidate microbiomes. Bioinformatics, biostatistics, and computational workflows help process and visualize large datasets to describe and predict microbial community networks, population dynamics, and distributed functional performances. Advanced monitoring and surveillance of water systems can be applied with flow cytometry and portable sequencing technologies at line. Wastewater-based epidemiology help track city metabolisms and develop new approaches for surveillance with sewage, such as driven under the current pandemic.

Lack of quantitativeness in molecular data often downscaled their engineering outreach. Multi-omics generate a mass of high-resolution datasets. Their use remain primarily descriptive. Moving beyond data should help develop theories and concepts for engineering practice. Conversely, clear engineering expectations have seldom been formulated toward an essential list of microbiological information for system design, operation, monitoring, and control. A ‘language of love’ combining systems microbiology and engineering targets should be formulated.

With the conference, we aim to engage interaction between scientists, engineers, practitioners and authorities to shape objectives for joint investigations on microbial ecology data and principles for water systems and industries.

Historically Delft has been a nucleus for applied microbiology, starting with the first observations of microorganisms by Antonie van Leeuwenhoek, Beijerinck introducing enrichment culturing, Soehngen developing the basis for anaerobic microbiology, Kluyver introducing the unity in biochemistry, Kuenen propelling continuous cultures for ecophysiology and discovering anammox, Heijnen developing microbial growth thermodynamics, followed by several breakthroughs in environmental and industrial biotechnology, sanitary and water engineering. We believe the traditional atmosphere of interaction between microbiology and engineering in Delft gives the perfect environment for the next MEWE meeting.

We aim to drive exchange between delegates on principles and integrative concepts across microbial ecology and water practice. The conference is organized in interaction with partner scientific institutions and engineering offices of the Netherlands.

We look forward to welcoming you next October 2021 virtually from Delft for the 9th IWA MEWE Specialist Conference.

David Weissbrodt (chair)

Mark van Loosdrecht (co-chair)