Bioremediation of agricultural solid waste leachates with diverse species of Cu (II) and Cd (II) by periphyton

Abstract

The aim of this work was to study the bioremediation of agricultural solid waste leachates with high-concentrations of Cu (II) and Cd (II) after washing the wastes with water and Na₂EDTA solution (0.2M). Results indicate that Cu (II) and Cd (II) are mainly comprised of Cu₂(OH)₂²⁺, Cu₃(OH)₄²⁺, CuOH⁺, Cu(H₂O)₄(OH)₂, Cd²⁺ and CdOH⁺ in the water-washed leachates and Cu(EDTA)^2-, Cu(HEDTA)^-, Cd(EDTA)^2- and Cd(HEDTA)^- in the Na₂EDTA-washed leachates. Cu (II) removal efficiency by selected native periphyton from the water- and Na₂EDTA-washed leachates were 80.5% and 68.4% respectively, and for Cd (II) it was 57.1% and 64.6%, because the periphyton was able to maintain a stable pH of the leachates and regulate its microbial composition and carbon metabolic capability to acclimate the chemical conditions of the leachates. This study provides a new biomeasure to treat leachates with high-concentration Cu²⁺ and Cd²⁺, and contribute valuable insights into the relationships between periphyton characteristics and heavy metals.

Keywords: Agricultural solids; Cd(2+); Cu(2+); Leachate; Periphyton; Remediation.