Effects of co-pyrolysis of rice husk and sewage sludge on the bioavailability and environmental risks of Pb and Cd

In this study, biochars were produced by co-pyrolysis of rice husk and sewage sludge, the environmental risk of heavy metal (Pd and Cd) in the biochars was assessed. Co-pyrolysis resulted in a lower yield but a higher C content compared with sewage sludge pyrolysis alone, the relative contents of Pb and Cd in biochars were declined. Co-pyrolysis process transformed the bioavailable heavy metals into stable speciation. The environmental risk assessment codes of Pb and Cd were reduced by 1-2 grades. The co-pyrolysis technology provides a feasible method for the safe disposal of heavy metal-contaminated sewage sludge.

Automated summary

Co-pyrolysis of rice husk and sewage sludge resulted in biochars with lower yield but higher carbon content, and reduced relative contents of lead and cadmium. This process transformed bioavailable heavy metals into stable speciation, reducing the environmental risk assessment codes of lead and cadmium by 1-2 grades. Co-pyrolysis technology provides a feasible method for the safe disposal of heavy metal-contaminated sewage sludge.