Microbial communities and processes in biofilters for post-treatment of ozonated wastewater treatment plant effluent

Daniel Sauter, Andrea Steuer, Kenneth Wasmund, Bela Hausmann, Ulrich Szewzyk, Alexander Sperlich, Regina Gnirss, Myriel Cooper, Thomas Wintgens

Research output: Contribution to journalArticlepeer-review

Abstract

Ozonation is an established solution for organic micropollutant (OMP) abatement in tertiary wastewater treatment. Biofiltration is the most common process for the biological post-treatment step, which is generally required to remove undesired oxidation products from the reaction of ozone with water matrix compounds. This study comparatively investigates the effect of filter media on the removal of organic contaminants and on biofilm properties for biologically activated carbon (BAC) and anthracite biofilters. Biofilms were analysed in two pilot-scale filters that have been operated for >50,000 bed volumes as post-treatment for ozonated wastewater treatment plant effluent. In parallel, the removal performance of bulk organics and OMP, including differentiation of adsorption and biotransformation through sodium azide inhibition, were carried out in bench-scale filter columns filled with material from the pilot filters. The use of BAC instead of anthracite resulted in an improved removal of organic bulk parameters, dissolved oxygen, and OMP. The OMP removal observed in the BAC filter but not in the anthracite filter was based on adsorption for most of the investigated compounds. For valsartan, however, biotransformation was found to be the dominant pathway, indicating that conditions for biotransformation of certain OMP are better on BAC than on anthracite. Adenosine triphosphate analyses in the media-attached biofilms of the pilot filters showed that biomass concentrations in the BAC filter were significantly higher than in the anthracite filter. The microbial communities (16S rRNA gene sequencing) appeared to be similar with respect to the types of organisms occurring on both filter materials. Alpha diversity also exhibited little variation between filter media. Beta diversity analysis, however, revealed that filter media and bed depth substantially influenced the biofilm composition. In practice, the impact of filter media on biofilm properties and biotransformation processes should be considered for the design of biofilters.
Original languageEnglish
Article number159265
Number of pages12
JournalScience of the Total Environment
Volume856
Issue numberPart 2
Early online date8 Oct 2022
DOIs
Publication statusEarly online - 8 Oct 2022

Keywords

  • Tertiary wastewater treatment
  • Ozonation
  • Biofiltration
  • Adsorption
  • Biotransformation
  • Microbial community

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