The invention provides an integrated internal circulation type
denitrification and
decarburization bio-
membrane reactor and an operating method thereof. The main body of the reactor consists of an anoxic zone on the lower part, an aerobic zone on the upper part and a
settling zone on the periphery of the aerobic zone; a composite filler is filled in the anoxic zone, and a water inlet
pipe is communicated with the bottom of the anoxic zone; the aerobic zone is partitioned into a filler zone for adding a carrier on the upper part and a mud-water
mixing zone on the lower part by adopting an
orifice plate, the anoxic zone and the aerobic zone are partitioned through an impermeable partition plate, and a plurality of
aeration pipes are arranged at the bottom of the aerobic zone and provided with air inlet pores; and the
settling zone consists of three parts, namely a
clean water zone, a contact
settling zone and a
sludge returning zone which are sequentially arranged from top to bottom, wherein the bottom of the
sludge returning zone is provided with a
sludge returning seam and communicated with the bottom of the aerobic zone. The reactor realizes zero
power consumption in sludge returning, and is compact in structure; and a back flushing
system is not required in the contact settling zone, and additional agents and carbon sources are not required, so that the reactor is low in running cost.