Sewage treatment system for pig farm breeding

The invention relates to a sewage treatment system for pig farm breeding. Excrement in a grating channel flows into a sewage collecting tank, the excrement in the sewage collecting tank is conveyed into a solid-liquid separation device through equipment such as a lifting pump for solid-liquid separation, and the solid-liquid separation device conveys separated liquid into a homogenate preheating tank; and the separated excrement residues are transported away to be processed and are produced into organic fertilizers to be sold, so that the economic benefits of pig farms are improved. After the excrement in the homogenate preheating tank is heated, the excrement is conveyed into an anaerobic reactor to produce biogas, biogas slurry generated by the anaerobic reactor is conveyed into a biogas slurry storage tank, and the produced biogas is conveyed into a gas storage cabinet through a pipeline to be stored. Meanwhile, a biogas boiler is communicated with the gas storage cabinet, and water in the biogas boiler is