The bio-resource utilization of sewage sludge is presented by preparation of novel waste sludge–doped graphite carbon nitride ( g -C 3 N 4 ) photocatalyst. The sludge flocs which constitute bacteria and organic substances served as a pore-forming framework in the catalyst, while the inorganic fractions including those transition metals and crustal metals can function as dopants for sludge-based g- C 3 N 4 composite. The physicochemical properties of as-prepared catalyst were well analyzed by multiple characterizations. The composite catalyst showed higher surface area (50 m 2 /g) and more mesoporous structures (8.9 × 10 −2  cm 3 /g) as compared with pristine g-C 3 N 4 (8.4 m 2 /g and 6.6 × 10 −2  cm 3 /g, respectively). The photoelectrochemical results showed that introduced sewage sludge impurities lowered down the photocarriers recombination efficiency and enhanced more efficient electron-hole separation by about 100 times. The photocatalytic activity was tested by degradation of typical dye Eriochrome Black T (EBT). The optimal sample improved removal of EBT by 56% in 90 min under ultraviolet irradiation ( λ  = 254 nm). According to the results of main metal ion leaching concentration and reuse tests, the composite catalyst exhibited excellent stability and repeatability.