Abstract: Piggery wastewater with low C and N was treated using an upflow anaerobic sludge bed biofilm reactor (UASBB) that coupled two biological contact oxidation ponds. Through this process, part of the total nitrogen (TN) and Chemical Oxygen Demand (COD) were removed, the concentration of ammonia and nitrite nitrogen ratio reached approximately 1:1 and the pH was adjusted to 7 to 8, which were favorable for anaerobic ammonium oxidation. Compared with the conventional activated sludge process, the coupled system can save 0.52 kg/(m3 d) of oxygen and 0.838 kg/(m3 d) of COD as well as recover 40.51 L/(m3 d) of CH4. The system was used to handle actual swine wastewater. When COD load reached 3 kg/(m3d), the average removal efficiency of COD for raw pig farm wastewater, first-stage biogas slurry and second-stage biogas slurry were 97, 94 and 94.4%, respectively. When TN load reached 0.51 kg/(m3 d), the above removal rates were 84.2, 82.5%and 83.8%, respectively. When ammonia load reached 0.3 kg/(m3 d), the above removal rates were 88.2, 91.9 and 91%, respectively.