The invention relates to a returned
sludge separation process improving the
sewage treatment dephosphorization and
denitrification efficiency, and belongs to the new
sewage treatment technology. The returned
sludge separation process has the specific contents that: firstly,
sludge at the bottoms of two settlement tanks flows inversely, and the sludge return flow R(R is equal to Qr / Q) is controlled between 50 and 85 percent; secondly, the return flow sludge enters into a
cavitation air concentration treatment system for performing the concentration and the separation, and is separated into two parts of supernatant fluid and concentrated sludge. The process needs the concentration percentage f (f is equal to Qr / Qs) of the
cavitation air concentration separation process to be controlled between 2.5 and 3.2, and requires the suspended
solid concentration in the supernatant fluid not to be more than 550 mg / L; thirdly, the separated supernatant fluid singly flows inversely to an
oxygen-poor tank for the
denitrification, the concentrated sludge flows directly and inversely to an anaerobic tank. The returned sludge separation process of the invention can effectively improve the removal efficiency of
nitrogen and
phosphorus in the
sewage treatment process with stable operation, and easily utilize the existing
wastewater treatment process to be changed and realized; meanwhile, the investment is small, and the operation cost is low.