TECHNOLOGY FOCUS - BIOLOGY - Preferred Method: In the step (i), the lysogeny broth culture medium comprises tryptone (10 g), yeast extract (5 g), sodium chloride (10 g) and distilled water, which is added to make up the volume to 1000 ml. In the step (v), the dissolved oxygen concentration is 2.5 mg/l; the pH is 7; PAM concentration is 120 mg/l, and the sludge concentration is 1800 mg/l; and the operating time is 45 days. The bio-agent combined treating method of sewage containing polyacrylamide, comprises (i) inoculating HWB-I and HWB-IV strain, respectively into lysogeny broth culture medium, activating for 24 hours at 28 degrees C, centrifuging for 5 minutes at 4000 revolutions/minute, discarding the supernatant, using sterilized water to respectively dilute the precipitate to 10 days to obtain HWB-I and HWB-IV activated bacterial solution, (ii) pouring polyacrylamide PAM culture medium (100 ml) to a 250 ml conical flask, then adding HWB-I activated bacterial solution (1 ml) and HWB-IV activated bacterial solution (1 ml), culturing for 24 hours under conditions of 30 degrees C and rotation speed of 140 revolutions/minute of shaker to obtain HWB mixed agent, (iii) taking activated sludge of the domestic sewage plant, adding into the SBR, controlling the concentration of sludge to 2000 mg/l, using domestic sewage as inlet water, adding PAM until the concentration is 20 mg/l and COD is 200-300 mg/l, (iv) , (iv) operating SBR reactor for every cycle, increasing the concentration of PAM by 20 mg/l until it reaches 100 mg/l, then operating for 20 days, (v) taking out the sludge in the SBR reactor, adding to the bio-contact oxidation reactor containing filler to aerate for 24 hours, then introducing water to the reactor, and using domestic sewage as inlet water, adding PAM until the concentration reaches 100 mg/l, controlling COD to 200-300 mg/l, dissolved oxygen concentration to 2-3 mg/l, and pH to 6-8, and hydropower retention time to 48 hours, operating for 10 days to complete the process, and (vi) adding HWB mixed agent to the SBR reactor to aerate for 48 hours according to the reaction volume of 800 D/L, controlling dissolved oxygen concentration, pH, PAM concentration to 100-150 mg/l, and sludge concentration to 1500-2000 mg/l, operating for 10 days to complete bio-agent combined treatment, where in the step (v),the adding amount of the filler is 40% of the bio-contact oxidation reactor; and the filler is branched polypropylene having length of 8-10 cm; and in the step (vi), during the course of aerating for 48 hours, controlling COD to 1000 mg/l, and adding PAM to reach 100 mg/l.