In this study hydrophilic cationic modified polyurethane foam (MPUF) carriers were developed to achieve faster water immersion and increased affinity for biofilm attachment in a moving bed biofilm reactor compared with generally used polyurethane foam (PUF) carriers. Biofilm was more susceptible to attachment to MPUF carrier than to PUF carrier. At the steady state of reactor operation, the amount of biofilm attached to MPUF carriers was 1.3 times more than that to PUF carriers. Phylogenetic analysis using 454-pyrosequencing revealed that biofilms attached to MPUF carrier displayed more complex community diversity, with higher Ace, Chao1 and Shannon indices and a lower Simpson index. (C) 2014 Elsevier Ltd. All rights reserved.