Microbial core communities in activated sludge plants are strongly affected by immigration and geography.

Background: The microbiota in wastewater treatment plants (WWTPs) and incoming wastewater is critical for the treatment process, the preservation of natural ecosystems and human health, and for the recovery of resources and achievement of sustainability goals. Both core species and conditionally rare and abundant taxa (CRAT) are considered process-critical but little is known about identity as well as true functional and ecological importance. Here, we present a comprehensive investigation of the microbiota of 84 municipal activated sludge (AS) plants with nutrient removal treating ~ 70% of all wastewater within a confined geographical area, Denmark (43,000 km).

Candidate biomarkers of antibiotic resistance for the monitoring of wastewater and the downstream environment.

Urban wastewater treatment plants (UWTPs) are essential for reducing the pollutants load and protecting water bodies. However, wastewater catchment areas and UWTPs emit continuously antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs), with recognized impacts on the downstream environments. Recently, the European Commission recommended to monitor antibiotic resistance in UWTPs serving more than 100 000 population equivalents.

Primary settling changes the microbial community of influent wastewater to wastewater treatment plants.

The continuous immigration of bacteria in influent wastewater strongly impacts the microbial community of activated sludge (AS) in wastewater treatment plants (WWTP), both in terms of species composition and their abundance. Therefore, it is of interest to elucidate the route of immigrating bacteria into the biological tanks, including the effect of primary settlers. These are commonly used pretreatment units that can possibly selectively increase or reduce the relative abundance of certain bacteria.

Full-scale activated sludge transplantation reveals a highly resilient community structure.

Well-functioning and stable microbial communities are critical for the operation of activated sludge (AS) wastewater treatment plants (WWTPs). Bioaugmentation represents a potentially useful approach to recover deteriorated systems or to support specific AS processes, but its application in full-scale WWTPs is generally problematic. We conducted a massive transplantation (in one day) exchanging AS from a donor to a recipient full-scale WWTP with similar process type (biological removal of nitrogen and phosphorus) and performance, but with differences in microbial community structure.

Microbial communities across activated sludge plants show recurring species-level seasonal patterns.

Microbial communities in activated sludge (AS) are the core of sanitation in wastewater treatment plants (WWTPs). Microbial communities in AS have shown seasonal changes, however, long-term experiments (>2 years) are rarely conducted, limiting our understanding of the true seasonal dynamics in WWTPs. In this study, we resolved the microbial seasonal dynamics at the species level in four municipal full-scale WWTPs, sampled every 7-10 days, during 3-5 consecutive years.

Mass-immigration determines the assembly of activated sludge microbial communities.

The assembly of bacterial communities in wastewater treatment plants (WWTPs) is affected by immigration via wastewater streams, but the impact and extent of bacterial immigrants are still unknown. Here, we quantify the effect of immigration at the species level in 11 Danish full-scale activated sludge (AS) plants. All plants have different source communities but have very similar process design, defining the same overall environmental growth conditions.

Novel syntrophic bacteria in full-scale anaerobic digesters revealed by genome-centric metatranscriptomics.

Short-chain fatty acid (SCFA) degradation is an important process in methanogenic ecosystems, and is usually catalyzed by SCFA-oxidizing bacteria in syntrophy with methanogens. Current knowledge of this functional guild is mainly based on isolates or enrichment cultures, but these may not reflect the true diversity and in situ activities of the syntrophs predominating in full-scale systems. Here we obtained 182 medium to high quality metagenome-assembled genomes (MAGs) from the microbiome of two full-scale anaerobic digesters.

Combined bioaugmentation with anaerobic ruminal fungi and fermentative bacteria to enhance biogas production from wheat straw and mushroom spent straw.

Bioaugmentation with anaerobic ruminal fungi and a pool of hydrogen-producing fermenting bacteria was tested on wheat straw (WS) and mushroom spent straw (MSS) with the aim of improving anaerobic digestion performance. Batch tests were set up to simulate a Bioaugmentation Anaerobic Digestion (BAD) treatment comparing single- (I-BAD) and two-stage (II-BAD) process configurations, at two reactor scales, 120 and 1200 ml (×10). In both cases, higher CH cumulative production was obtained in the II-BAD configuration on WS (65.