This paper was completed by a research scholar at the College of Chemistry and Chemical Engineering of Jiangsu Normal University. The paper discusses the changes in the form and effectiveness of heavy metals before and after aerobic fermentation of municipal sludge, and published it in the important journal .

Taking the dewatered sludge of Xuzhou Guoyu Water Operation Company as the research object, the exogenous bacteria (Bacillus licheniformis and Pseudomonas putida) were added for aerobic fermentation. Various forms of heavy metals in the sludge were extracted by BCR method, and the contents of each form were determined by atomic absorption and atomic fluorescence spectrometry. The results showed that aerobic fermentation could reduce the bioavailability of Cr, As and Pb in sludge; the bioavailability of Cu, Zn, Cd and Ni increased after fermentation, but their effectiveness after fermentation with exogenous bacteria It was lower than the control group; the exchangeable content of Hg before and after fermentation was not measured.

The upper residue was transferred to a 100 mL beaker, dried in an oven, and weighed 0.2 g of sludge in a PTFE-sealed microwave digestion tank, and 2 mL of hydrochloric acid, 8 mL of hydrofluoric acid, and 10 mL of nitric acid were added. After standing for 20 min, tighten the cover and place it on the turntable of the microwave digestion instrument. Digestion was carried out at 120 °C for 5 min, digestion at 180 °C for 30 min, digestion at 120 °C for 5 min, and after digestion, cooling for 30 min. Then acid in the fume hood for 20 min, wash the digestion tank 3 times with 2% nitric acid, and combine the digestion solution and the washing solution into a 100 mL centrifuge tube. After centrifugation in a 4000 r /min centrifuge for 30 min, the supernatant was filtered through a quantitative filter paper, and the filtrate was transferred to a 50 mL centrifuge tube and made up to 45 mL with a 2% nitric acid solution.