Removal of arsenic in the leachate by a porous carbonaceous solid waste generated from pyrolysis of oily sludge

The leachate derived from lead smelting slag site is a potential hazard to the soil and water nearby due to its excessively high arsenic content. A porous carbonaceous solid waste (PCSW), resulting from the pyrolysis of oily sludge of tank bottom, was proposed to remove arsenic (As) from leachate. According to the results of As removal from simulated solution, PCSW can remove As efficiently and synchronously increase solution pH at equilibrium. The removal efficiency of As was 96.26% and the solution pH at equilibrium was 8.98 under the optimal conditions of PCSW dosage of 3 g⋅L−1, and initial As concentration of 12 mg⋅L−1 with the initial pH of 7.5. The adsorption rate of As was 0.319 g·(mg·min)−1, and the maximum adsorption capacity of As on PCSW was 45.314 mg⋅g−1. The removal of As from the solution was attributed mainly to the formation of stable calcium-arsenate precipitations and Fe–As complexes on PCSW surface. PCSW can also simultaneously and effectively remove the heavy metals (As, Pb, Zn, Cu, Cd) in leachate from lead smelting slag sites, and the residual concentration of all heavy metals were lower than the emission concentration (GB25466-2010, China). It is proved to be feasible for PCSW application in the treatment of leachate containing heavy metals.