NOVELTY - Purified terephthalic acid (PTA) sewage anaerobic reactor comprises a reactor shell, where the reactor shell is provided with a biogas collection area, a three-phase separation area and an anaerobic reaction area from top to the bottom respectively. The biogas collection area is fixed on the top of the reactor shell via a gas collection pipe. A water inlet pipe is connected to an anaerobic reaction module and passes via bottom part of the fixed reactor shell. A water outlet pipe is connected to the three-phase separation area and passes through the upper part of the fixed reactor shell.    USE - Used as a PTA sewage anaerobic reactor.    ADVANTAGE - The reactor has stable operation and does not allow anaerobic sludge to flow out easily.    DETAILED DESCRIPTION - PTA sewage anaerobic reactor comprises a reactor shell, where the reactor shell is provided with a biogas collection area, a three-phase separation area and an anaerobic reaction area from top to the bottom respectively. The biogas collection area is fixed on the top of the reactor shell through a gas collection pipe. A water inlet pipe is connected to an anaerobic reaction module and passes through the bottom part of the fixed reactor shell. A water outlet pipe is connected to the three-phase separation area and passes through the upper part of the fixed reactor shell. The reactor further comprises a circulation explorer whose one end is connected with a circulation water distributor and the other end is connected with the water inlet pipe. The water inlet pipe and the circulation explorer are respectively provided with a feed pump and a circulation pump. The three-phase separation area is provided with a three-phase separation module and a sludge hopper is set at the bottom of the three-phase separation module. The upper port of a sludge collection tube is connected with the sludge hopper bottom, and the lower port of the sludge collection tube is connected with the circulation explorer. An INDEPENDENT CLAIM is also included for using the PTA sewage anaerobic reactor comprising: (i) inoculating the seed sludge into the reactor shell via reactor port, where the initial filling is 1/2 of the anaerobic reaction zone; (ii) starting the circulation pump and controlling the pump flow via a frequency by adjusting the flow rate to 3 m/hour in the anaerobic reactor; (iii) starting the feed pump, passing the PTA sewage into the feed pump via water inlet pipe and then into the water distributor and into the anaerobic reaction zone via water inlet, where the organic matter in the PTA sewage suspended in the anaerobic reaction zone contact with the anaerobic granular sludge for granular sludge adsorption and anaerobic bacteria degrades water, methane, carbon dioxide and carbon monoxide; (iv) passing the generated biogas into the biogas collection area in the reactor, passing the biogas into the reactor shell via collection tube which leads to the access for post-processing, where some portion of the anaerobic sludge enters into the three-phase separation module, passing the anaerobic sludge into the sludge hopper by the inclined plate deposited on the inclined plate sedimentation area, passing the sewage into the labyrinth gas-liquid separation zone and then into biogas collection area, where the sewage flows into the catchment weir and water tank, finally passing sewage into the reactor via water outlet pipe; and (v) passing the sewage from the sludge hopper into the circulation explorer via the sludge collection pipe, and returning the circulating water into the water inlet via circulation pump, and finally passing PTA sewage into the reaction zone.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic representation of the PTA sewage anaerobic reactor.