Transformation behavior of lead fractions during composting of lead-contaminated waste

The transformation behaviors of Pb fractions during composting of Pb-polluted waste without inoculants and with the inoculants of Phanerochaete chrysosporium were studied. Results show that the active Pb ions with high toxicity and transferability are transformed into the inactive Pb with low toxicity and transferability, confirming that Pb ions can be efficiently immobilized during composting without or with the inoculants. The soluble-exchangeable Pb in composting without inoculants reaches 49.0 mg/kg at day 60, while that with the inoculants is reduced to 0 mg/kg dry mass compost. The higher contents of organic-bound Pb (59.0 mg/kg) and residual Pb (69.2 mg/kg) with low toxicity are found after 60-day composting with inoculants, compared with those without inoculants. The above data indicate the better immobilization effect of Pb and the greater alleviation of Pb hazards in composting with the inoculants of Phanerochaete chrysosporium than without inoculants, which may be due to the more microbial biomass and the higher pH value in composting of Pb-polluted waste with inoculants.