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Aims:  The aim of this study was to develop an assay system that can quantify the amount of biomass in biofilms formed by different isogenic mutants of an Escherichia coli K‐12 strain. Methods and Results:  The reported assay, which is based on the BacTiter‐Glo™ assay from Promega, uses bioluminescence to detect the intracellular concentration of ATP, which correlates with viable bacterial cell numbers. The quantitative data obtained with this ATP assay were compared to those obtained with the conventional crystal violet assay. As a qualitative control, scanning electron microscopy was performed. Conclusions:  The ATP assay, the crystal violet assay and scanning electron microscopy yielded similar results for six of the eight strains tested. For the remaining two strains, the images from the scanning electron microscopy confirmed the results from the ATP assay. Significance and Impact of the Study:  The ATP assay, in combination with other quantitative and qualitative assays, will allow us to perform genetic studies on the regulatory network that underlies the early steps in E. coli biofilm formation.

This study evaluated the application of recuperative thickening (RT) to enhance anaerobic digestion (AD) performance for AD systems with thermal hydrolysis pretreatment (THP). RT was applied for two different reasons: (a) for increasing the sludge retention time (SRT) to degrade slowly hydrolyzable materials more efficiently and (b) for maintaining SRT at decreased hydraulic retention time (HRT) thus showing potential for increased AD throughput rates. A SRT increase from 15 to 30 days by RT application did not improve AD performance or hydrolysis rates significantly as 15‐day SRT was already a factor 2 higher than the estimated washout SRT. When applying RT to increase throughput rates (HRT of 7 days) while maintaining 15‐day SRT, no negative impact on biogas production or hydrolysis kinetics was observed. It was estimated that RT application on THP digesters can increase digester throughput by 100% and thus show clear potential for further AD intensification. Practitioner points Increased SRT from 15 to 30 days through recuperative thickening application did not improve biogas production. A lower required minimum SRT (6–7 days) was estimated in THP‐AD systems compared to conventional AD. Operation at decreased HRT by RT application resulted in similar AD performance under constant organic loading rates. A 100% increase in throughput rates can be applied using RT without decreasing AD performance.