Bed expansion behavior and sensitivity analysis for super-high-rate anaerobic bioreactor

Bed expansion behavior and sensitivity analysis for super-high-rate anaerobic bioreactor (SAB) were performed based on bed expansion ratio (E), maximum bed sludge content (V_(pmax)), and maximum bed contact time between sludge and liquid (T_(max)). Bed expansion behavior models were established under bed unfluidization, fluidization, and transportation states. Under untluidization state, E was 0, V_(pmax) was 4867 ml, and T_(max) was 844-3800 s. Under fluidization state, E, V_(pmax), and T_(max) were 5.28%-255.69%, 1368-4559 ml, and 104-732 s, respectively. Under transportation state, washout of granular sludge occurred and destabilized the SAB. During stable running of SAB under fluidization state, E correlated positively with superficial gas and liquid velocities (u_g and u_l), while V_(pmax) and T_(max) correlated negatively. For E and V_(pmax), the sensitivities of u_g and u_l were close to each other, while for T_(max), the sensi-tivity of u_l was greater than that of u_g. The prediction from these models was a close match to the experimental data.