Stable Remediation of Arsenic-contaminated Soil by Sludge-based Biochar

Sewage sludge-based-biochar and bioleaching sewage sludge-based-biochar were used as restorative to remediate arsenic polluted soil. Brassica chinensis was planted in pot to explore the influence of biochar on soil and plants absorbing arsenic. Arsenic content in pots were 20, 40, 60, and 100 mg·kg^-1. The results show that: After adding biochar, the soil pH was decreased, and the content of sulfur, phosphorus, iron, and aluminum were greatly increased. However, the aluminum content of bioleaching sludge-biochar is 4.64 mg·g^-1 lower than that of sludge-biochar. The effective arsenic content in the soil was reduced by 16.9%-33.6%; while the fixed arsenic content was increased by 8.3%-31.0%. Compared with sludge-biochar adding pots, the bioleaching sludge-biochar adding pots had a higher residual arsenic percentage in 3.9-11.4 percentage point. The application of biochars can significantly reduce the arsenic content in Brassica chinensis, and the arsenic enrichment coefficient is about 0.1, but there is no significant difference between the two biochars treatments.