Anaerobic bioreactor

The invention relates to an anaerobic bioreactor which comprises a reactor (1), an inlet water distributor (2), a reflux water distributor (3), a circulating pump (4) and a three-phase separator (5), the inlet water distributor (2) is mounted at the bottom of the reactor (1), and reactor treatment inlet water and reflux liquid conveyed by the circulating pump (4) are uniformly distributed to the bottom of the reactor; the reflux water distributor (3) is mounted in the middle of the reactor (1), collects mixed liquid in the reactor, and refluxes to the bottom of the reactor through the circulating pump (4) to form internal reflux continuous circulation; and the three-phase separator (5) is arranged at the upper part of the reactor (1) and is used for carrying out mud-water separation on the mixed liquid. Compared with the prior art, the problems that the separation effect of sludge flocs or sludge particles and water is poor, and water flows out and mud leaks due to attachment of small bubbles are solved by im