Technological transfer to demonstrative scale of SBBGR technology for municipal wastewater treatment

The paper reports the results obtained during an experimental campaign aimed at transferring aerobic granulation to a demonstrative SBBGR system (i.e., a submerged biofilter that operates in a "fill and draw" mode) for the treatment of municipal wastewater by financial support of the European Commission, within the framework of Life-Environment Programme (PERBIOF Project; www.perbiof-europe.com). The results show that following the generation of granular biomass during the start-up period, the SBBGR was able to remove 80-90% of COD, total suspended solids and ammonia occurring in primary effluent from a municipal wastewater treatment plant even when the minimum hydraulic residence time (i.e., 4 h) was investigated. The process was characterised by a sludge production almost one magnitude order lower than commonly reported for conventional treatment plants. The granular biomass was characterised by a high density (i.e., 150 gTSS/Lbiomass) that allowed a biomass concentration as high as 35 kgTSS/m3bed to be achieved. Proteobacteria were found as main microbial components of the granular biomass by applying Fluorescence In Situ Hybridization (FISH). No significative changes in microbial composition were observed during reactor operation.