Risk analysis of pyrolyzed biochar made from paper mill effluent treatment plant sludge for bioavailability and eco-toxicity of heavy metals.

Highlights: [•] Disposal of toxic sludge containing heavy metals poses an environmental risk. [•] Pyrolysis of sludge was performed to explore the potential of biochar for reuse. [•] The effect of pyrolysis temperature on partitioning of heavy metals was studied. [•] Fractionation and bioavailability of heavy metals in sludge and biochar was analyzed. [•] The leachability and ecotoxicity of heavy metals in biochar were determined. [Copyright &y& Elsevier]