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

- Periphyton is effective and sustainable in removing Cu and Cd from leachates.
- Minimizing pH fluctuation benefited Cu and Cd removal by periphyton.
- Periphyton acclimated to leachate conditions by regulating its microbial composition.
- Periphyton is promising in treating agricultural solid waste leachate with Cu and Cd.

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 (0.2 M). 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.