Efficient energy-saving sewage treatment system

The invention provides an efficient energy-saving sewage treatment system. The system comprises an adjusting tank, an oil separation sedimentation anaerobic tank group, a double-micro-generator, a deep oil separation sedimentation anaerobic tank, a potential energy biological sewage purifier, a sedimentation tank and an adsorption purification tank which are sequentially arranged in the sewage flowing direction, wherein the potential energy biological sewage purifier is composed of a plurality of modified potential energy reoxygenation biological rotating discs; the plurality of modified potential energy reoxygenation biological rotating discs are arranged in a spiral step shape; sewage spirally flows among the plurality of modified potential energy reoxygenation biological rotating discsfrom top to bottom; and for the vertically adjacent modified potential energy reoxygenation biological rotating discs, a third water outlet of the modified potential energy reoxygenation biological rotating disc positioned at