Full-scale activated sludge transplantation reveals a highly resilient community structure. (1st February 2023)

• Record Type: Journal Article
• Authors: Dottorini, Giulia; Wágner, Dorottya Sarolta; Stokholm-Bjerregaard, Mikkel; Kucheryavskiy, Sergey; Michaelsen, Thomas Yssing; Nierychlo, Marta; Peces, Miriam; Williams, Rohan; Nielsen, Per Henrik; Andersen, Kasper Skytte; Nielsen, Per Halkjær
• Is Part Of: Water research. Volume 229(2023)
• Publication Date: 2023-02-01
• Subjects: Bioaugmentation -- Activated sludge transplantation -- Microbial community structure -- Time-series analysis -- Resilience -- Mass-immigration; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2022.119454
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: Activated sludge biomass was transplanted between two full-scale plants. The process performances of the recipient plant were maintained. The microbial community of the recipient plant was resilient to transplantation. The addition and retention of new species to the recipient plant was not successful. Mass-immigration likely affected the outcome of transplantation. Abstract: 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. The treatment performance in the recipient plant was not compromised and the effluent quality remained stable. The AS community structure of the recipient plant was initially very similar to the donor AS, but it almost completely restored the pre-transplantation structure approximately 40 days after transplantation, corresponding to 3 times the solid retention time. Most of the unique species of donor AS added to recipient AS disappeared quickly, although some disappeared more slowly the following months, indicating some survival and potentially a time limited function in the recipient plant. Moreover, the addition in higher abundance of most species already present in the recipient AS (e.g., the polyphosphate accumulating organisms) or the reduction of the abundance of unwanted bacteria (e.g., filamentous bacteria) in the recipient plant was not successful. Moreover, we observed similar abundance patterns after transplantation for species belonging to different functional guilds, so we did not observe an increase of the functional redundancy. Investigations of the microbial community structure in influent wastewater revealed that for some species the abundance trends in the recipient plant were closely correlated to their abundance in the influent. We showed that a very resilient microbial community was responsible for the outcome of the transplantation of AS at full-scale WWTP, potentially as a consequence of mass-immigration from influent wastewater. The overall results imply that massive transplantation of AS across different WWTPs is not a promising strategy to permanently solve operational problems. However, by choosing a compatible AS donor, short term mitigation of serious operational problems may be possible. Graphical abstract: Image, graphical abstract