Remediation of Heavy Metal Contamination in Paddy Soils through Soil Leaching Combined with Biosorption

Soil contamination and associated pollution plays a detrimental role in the sustainable development of agriculture. In this paper, a novel approach, soil washing combined with biosorption, to remove heavy metal from paddy soil, which contaminated by high levels of Cd, Pb, Cu, Cr and Zn, was evaluated in laboratory-scale batch based on environmental and efficient analysis. The mixture of 3M HCl and 0.2M EDTA solution was used as the leaching agent. Collagen fiber modification persimmon tannin (PTCF) and chitosan functionalization persimmon tannin (PTCS) were used as the biosorbents. The beaker and enlarge experimental results showed that PTCF, PTCS, mixture of PTCF and PTCS can effectively remove five metal ions from leaching liquid of contaminated soil. For the prepared Grade III soil which is critical conditions for the growth of plants (Environmental Quality Standard for Soils/GB 15618-1995), the metal removal efficiency was achieved at 53.36%, 44.89%, 37.73%, 7.60% and 6.02% for Cd, Pb, Cu, Cr and Zn at 10% mixture PTCF and PTCS adsorbent (1: 1), respectively. All the results proved that the feasibility of the soil washing combined with biosorption remediation has great potential in the treatment of heavy metal pollution.