Attachment of anaerobic ammonium-oxidizing bacteria to augmented carrier material

The formation of stable and highly active anammox biofilm is a lengthy process leading to long start-up times of deammonifying reactors of several months or more. This study aims to provide a quick solution to the problem of long start-up periods by pretreating the surface of carrier material. Two different techniques were investigated. The first one focused on growing a layer of heterotrophic biofilm on the surface of the plastic carriers prior to inoculation with anammox biomass. Specific anammox activity increased by almost 400% as compared to seed values and was equal to 250 mg NH₄-N/gVSS/L•d. In the second technique, the carrier material was coated with a layer of granular-activated carbon to provide a higher surface area. The anammox activity increased by approximately 50%. In comparison, the control reactor did not develop any biofilm and no anammox activity was detected. Rapid attachment of the anammox biomass was achieved in a reactor with media that had a predeveloped layer of a biofilm. In a way, this approach is analogous to a primer or an undercoat that is put on materials before painting to ensure better adhesion of paint to the surface, hence the suggested name - bioprimer.