Methanotrophic denitrification was studied in sequencing batch reactors (SBR) with biomass immobilized in polyurethane foams. The reactors were inoculated with a blend of marine and mangrove sediments (Sed-SBR) and anaerobic sludge (AnS-SBR) under anoxic condition. Methane was provided as the only external electron acceptor and carbon source.

Methanotrophic denitrification has risen as an alternative to nitrogen removal in waters which are poor in organic content. There are several problems related to its applicability, such as the slow growth and specific denitrification rates and long times required to establish methanotrophic-denitrifiers community. A possibility to overcome the slow growth is to enhance biomass retention. Therefore, methanotrophic denitrification was studied in sequencing batch reactors (SBR) with biomass immobilized in polyurethane foams. The reactors were inoculated with a blend of marine and mangrove sediments (Sed-SBR) and anaerobic sludge (AnS-SBR) under anoxic condition. Methane was provided as the only external electron acceptor and carbon source. Methane supported denitrification to a small extent (<2.0 mgN.gVSS-1d-1) and also supported biomass growth for the AnSreactor in 10% of initial volatile suspended solids. Aerobic methanotrophic organisms affiliated to Methylomonas genus were abundant in both enriched samples. It is hypothesized they were able to grow using residual oxygen. Furthermore, various heterotrophic groups were also identified, indicating that methanotrophs allowed establishment of a diverse community, even submitted to adverse conditions.