Abstract: Based on the analysis of heavy metals, nutrients and sulfate in bioleached sewage sludge, the feasibility of this sludge in land application was approached in this paper. The results showed that after bioleaching, most of the heavy metals in the supernatant of the sludge were removed through solid-liquid separation, and the removal efficiency of Cu, Pb and Zn was 84.1%, 34.8% and 80.0%, respectively. The heavy metals remained in the sludge were mainly existed in stable forms, which made a higher security for land application. The bioleaching loss of the nitrogen, phosphorus and potassium in sludge was 38.2%, 52.1% and 42.8%, respectively, but the sludge still remained satisfactory fertilizer value. X-ray diffraction analysis indicated that the sulfate remained in the sludge after bioleaching was mostly combined with calcium, resulting in a negligible environmental impact.

Key words: Paddy soil, Cd contamination, Soil microbial biomass, Soil enzymatic activity, Rice physiological indices