The invention discloses a
sewage treatment device,
system and method. The
sewage treatment device comprises a reaction column, an aerator, a water feeder and a water drainage device, wherein the reaction column is vertically arranged, the water feeder is arranged below the reaction column, the aerator is arranged at the bottom of the reaction column, the water drainage device is arranged above the reaction column, an
activated sludge water purification region, a
biofilm water purification region and a clear water region are arranged in the reaction column from bottom to top according to a
water flow direction sequentially; and a bearing layer with the capabilities of water permeability and
sludge isolation is arranged between the
activated sludge water purification region and the
biofilm water purification region. The
sewage treatment system comprises a plurality of
sewage treatment devices which are connected in series with one another. The
sewage treatment method comprises the following steps: (1) a starting phase, namely, injecting
activated sludge into the activated
sludge water purification regions of the reaction columns in each
sewage treatment device in the sewage
treatment system, and carrying out smothering
aeration; and (2) a continuous running phase, namely, regulating according to the following principles: the longer the
running time is, the larger the water inlet quantity is, and the larger the
aeration quantity is. The sewage treatment device,
system and method are strong in loading ability, long in
backwashing period and low in
energy consumption and
sludge discharge.