The invention discloses a biological
sewage reaction system and an upgrading and expanding method. The biological
sewage reaction system comprises a biological
sewage reaction tank; an anoxic
activated sludge region, an anoxic / anaerobic
activated sludge region and an anoxic / aerobic transition region are sequentially communicated, an MBBR (
Moving Bed Biofilm Reactor) treatment region is communicated with an aerobic
activated sludge region through a perforation in the bottom of a partition wall, and the MBBR treatment region is communicated with a pure aerobic activated
sludge region through an
effluent screen mesh; the anoxic / aerobic transition region is communicated with the aerobic activated
sludge region, and the pure aerobic activated
sludge region is communicated with the anoxic activated sludge region through an internal
reflux submersible sewage pump; the pure aerobic activated sludge region is communicated with a secondary
sedimentation tank through a pipeline, and the secondary
sedimentation tank is communicated with the anoxic activated sludge region through a return pipeline. The traditional CAST (Cyclic
Activated Sludge Technology) / CASS (Cyclic
Activated Sludge System) biological tank is modified, and therefore, on the premise that the modifying cost is reduced, the capacity for removing
total nitrogen (TN) and
total phosphorus (TP) organisms in the tank is effectively improved, the
pollution load (expanding) treatment capacity is improved, and the
sewage treatment efficiency is increased.