Dispersion characteristics of a spiral symmetry stream anaerobic bio-reactor

The dispersion characteristics of an anaerobic reactor affect its flow patterns and consequently impact its removal efficiency η (assumed). The dispersion characteristics of a spiral symmetry stream anaerobic bio-reactor (SSSAB) were investigated under overall and local dispersion conditions, which were well described by the axial dispersion model and increasing-sized CSTRs model, respectively. The flow patterns of the SSSAB under super-high (hydraulic loading rate L = 18.45 L L−1 d−1, biogas production rate G = 80.24 L L−1 d−1) and high loadings (L = 9.23 L L−1 d−1, G = 40.12 L L−1 d−1) tended to the completely mixed flow, while under middle (L = 4.61 L L−1 d−1, G = 20.06 L L−1 d−1) and low loadings (L = 2.31 L L−1 d−1, G = 10.03 L L−1 d−1) tended to the plug-flow. The axial dispersion decreases along the height of the SSSAB. The fluid in the reactor mixed completely after the actual completely mixed time θacm, which decreases from 1.54 to 0.44 with the loading rate increases. The maximum and minimum values of the mean increasing rate vm are 14.00 and 0.72 at super-high and loading rate, respectively. And η positively correlates to the number of tanks N and negatively to vm. Reducing vm and enlarging N are the favorable method to further improve the treatment efficiency for the reactor operated under low or medium loading and high or super-high loading conditions, respectively.