In recent years, a potential controversy has arisen that whether the metal speciation in solid matrix determined its electrokinetic (EM) removal efficiency or by contrast. In present study, Cu and Zn in anaerobic digestate were selected as candidates to investigate the relation between the species of metal and EM treatment. The obtained results show that the removal efficiency for each fraction decreased in the order as follows: exchangeable >= bound to carbonates > bound to Fe-Mn oxides > bound to organic matters residual. For both Cu and Zn, their total removal performance was dependent on their dominant fraction in the digestate. A constant pH maintenance around the digestate via circulation of acid electrolyte is an optional operation because a strong acid atmosphere (pH<2) around the digestate can be formed automatically as EM time elapses. Despite that many reactions occurred during EM process, the species distribution of Cu and Zn in the digestate determined their total EM removal efficiency essentially. (C) 2014 Elsevier B.V. All rights reserved.