As shown above, the reactive nano-Fe0 released more Fe2+ ions and promoted the catalytic reaction at relatively higher pH. On the other hand, NZVI/NaY catalyst was still active at extremely low initial pH. The desired pH for an effective Fenton reaction could be obtained by utilizing the reaction-released OH− instead of chemical addition. This pH adjustment not only allowed the Fenton reaction to occur in its favorable pH range, but also benefited any potential subsequent biological treatment process or a final discharge