Performance of DOuble Circulation Anaerobic Sludge bed reactor: Biomass self-balance.

The calcification of Anaerobic Granular Sludge is a serious problem in the application of anaerobic methanization biotechnology. Regular replacement of calcified sludge with exogenous sludge is an effective method, but it is costly and troublesome. A new DOuble Circulation Anaerobic Sludge bed reactor was developed for the enhanced production of endogenous sludge to self-balance the discharge of calcified sludge. The sludge washout rate was demonstrated to fall by 45% and the sludge proliferation rate was shown to rise by 230%, offsetting the regular discharge of calcified sludge. The zoogloea in 100 μm dimension was revealed to be the intermediate component of sludge. The sludge proliferation mode was proposed as follows: (i) Growth of sludge; (ii) Self-cracking of sludge to release fragmental sludge; (iii) Migration of fragmental sludge by self-floatation; (iv) Accumulation of suspended sludge in the sedimentation chamber; (v) Re-granulation of suspended sludge with the aid of Venturi effect.