Phytotoxicity Assessment of Electrochemically Anodic Oxidized Coordination Structures Dyeing Wastewater

Anodic oxidation using boron-doped diamond (BDD) anode offers a promising treatment method for the deep treatment of dyeing wastewater. However, limited attention has been on the phytotoxicity evolution and their cause of degraded wastewater. Here, two representative coordination-structured dyeing wastewaters were first degraded using a BDD anode, and the resulting degradation intermediates were analyzed. Subsequently, lettuce seed root length, shoot length, and germination rate were evaluated to assess wastewater's phytotoxicity at different degradation periods. Finally, acute toxicity and the relative concentration changes of intermediates were further analyzed to identify the causes of toxicity. Results indicated that the treated wastewater was more toxic than pre-oxidation due to the generation of multiple toxic intermediates, significantly inhibiting seed growth. The synergistic effects of toxic substances and Na₂SO₄ electrolytes contributed to increased toxicity. This study demonstrated that the decolorization process of dyeing wastewater through anodic oxidation was toxic and provided a basis for evaluating the agricultural reuse potential of oxidized wastewater.