A novel carrier media for enhancing cell immobilization and methane metabolism in biofilm reactors

This study evaluates the feasibility of a novel patented carrier media for cell immobilization, developed within the scope of this research and named Henrique Dornelles 1 (HD1). The carrier was tested in an Anaerobic Fluidized Bed Reactor (AFBR) applied to municipal wastewater treatment and compared to a control AFBR filled with a conventional sand bed. Each HD1 carrier (11 mm internal diameter and 15 mm external diameter) consists of a synthetic polyaniline membrane cold-welded to two rigid polyvinyl chloride (PVC) rings, forming an open-ended structure that allows fluid to pass through the membrane and enables cell adhesion in the form of a biofilm. In terms of reactor performance, no significant difference was observed in the average COD removal efficiency between the two systems. However, the use of HD1 seems more viable due to its significantly lower material requirement (190.2 g) compared to sand (800 g), suggesting the potential for downsizing treatment facilities without compromising efficiency. The lower density of HD1 also may suggests a reduced recirculation flow rate and, consequently, lower pumping costs. Furthermore, HD1 promoted enhanced methanogenic activity and favored the selection of methanogenic archaea, particularly Methanothrix, which reached a relative abundance of 17.8 % in the HD1 system, compared to only 0.3 % in the sand bed. The geometric features and high specific surface area of HD1 provide optimized conditions for biomass development and improved substrate diffusion into the inner layers of the biofilm.