Dynamic behavior and concentration distribution of granular sludge is highly dependent on the ecological environment of microbial communities and substrate degradation efficiency along bed height. Both were modeled and verified through experiments in a super-high-rate spiral anaerobic bioreactor (SSAB). The sludge transport efficiency of upmoving biogas (k(t),(n-1)) displaying dynamic behavior of granular sludge in SSAB were predicted and found to be much lesser than of upflow anaerobic sludge blanket (UASB). The bed concentration distribution (C-m,(n-1)/C-m,(n)) which represented concentration distribution of granular sludge were also quantitatively predicted in two feeding strategies. Parametric sensitivity suggested that k(mn-1) was significantly influenced by spiral angle, outer radii of spiral rectangular channel, settling velocity of granular sludge and superficial liquid velocity (v(1)), while C-m,(n-1)/C-m,(n) was affected by v(1) and superficial biogas velocity. In addition, some measures were also suggested to optimize designs and operations of such bioreactors. (C) 2012 Elsevier Ltd. All rights reserved.