| Popis: |
Biochar was prepared by anaerobic pyrolysis of the residual sludge collected from the biochemical treatment system of pharmaceutical, dyeing,and paper-making wastewater. The emission of toxic gas was explored, and the physicochemical properties of various sludge biochar were characterized. Furthermore, biochar was used to treat industrial wastewater, and its toxic effect on aquatic organisms was investigated. The experiment results showed that the yield of sludge biochar was 53%-71%. CO2 emission decreased with the increase of pyrolysis temperature,whereas CO, CH4, H2, and other gases emission increased. The content of C in sludge biochar was relatively low, and it contained iron, manganese, chromium, lead, etc. The content of iron was the highest, which was 5 540 mg in 1 kg dyeing sludge biochar. Compared with low and medium-temperature sludge biochar, high-temperature sludge biochar had the best treatment effect on effluent from the secondary sedimentation tank. After 24 h reaction, 0.5 g/L pharmaceutical sludge biochar could remove 88.5% of sulfide, but could not decolorize. Dyeing sludge biochar could remove COD and meet the draining standard, but its removal ability towards anilines was poor. Paper sludge biochar could remove COD, TN, and chroma in wastewater. In addition, the sludge biochar could release a small amount of metal from itself during wastewater treatment. Low doses of sludge biochar had no significant effect on the growth of aquatic organisms. However,as the sludge biochar increased to 2.0 g/L, the number of Escherichia coli colonies decreased by 5.3%-11.2%, and the growth inhibition rate of Chlorella sp. was 9.1%-12.3%. |
