溶解氧对生物海绵铁体系中海绵铁腐蚀的影响

为了探究溶解氧对生物海绵铁体系海绵铁溶出的影响,将海绵铁介入活性污泥中形成生物海绵铁体系,通过模拟实际反应器中海绵铁的腐蚀状态,测量生物海绵铁体系中总Fe(TFe)含量,研究了溶解氧对海绵铁溶出量的影响,并将海绵铁制作成工作电极介入活性污泥中,利用AUTOLAB电化学工作站研究了溶解氧对生物海绵铁体系中海绵铁腐蚀速率及极化电阻的影响。结果表明：在生物海绵铁体系中,海绵铁的TFe溶出量与反应体系的DO浓度呈正相关,且随着运行时间的增加,影响作用越来越明显。随着活性污泥混合液中溶解氧的增加,腐蚀电位负移,腐蚀电流正移,腐蚀倾向加大,腐蚀效果变强。通过极化曲线及其参数分析得出不同溶解氧浓度下海绵铁极化电阻排序为(6.5±0.5) mg/L<(3.5±0.2) mg/L<(0.5±0.2) mg/L,缺氧条件下,腐蚀阻力较大,溶解氧能够减小极化电阻,促进海绵铁填料的腐蚀。

EFFECT OF DISSOLVED OXYGEN ON CORROSION OF SPONGE IRON IN BIOLOGICAL SPONGE IRON SYSTEM

In order to investigate the effect of dissolved oxygen on the dissolution of sponge iron in the biological sponge iron system, sponge iron was involved in the activated sludge to form the biological sponge iron system. By simulating the corrosion state of sponge iron in the actual reactor and measuring the TFe content in the biological sponge iron system, the effect of dissolved oxygen on the dissolution of sponge iron was studied. By making sponge iron into a working electrode and intervening into the activated sludge, the effect of dissolved oxygen on the corrosion rate and polarization resistance of sponge iron in the biological sponge iron system was studied by AUTOLAB electrochemical workstation. The results showed that in the biological sponge iron system, TFe dissolution of sponge iron was positively correlated with the DO concentration of the reaction system, and the effect became more and more obvious with the prolonging of running time. With the increase of dissolved oxygen in activated sludge mixed solution, the corrosion potential moved negatively, the corrosion current moved positively, the corrosion tendency increased, and the corrosion effect became stronger. Through the polarization curve and parameters analysis, the polarization resistance of sponge iron under different dissolved oxygen followed the order of (6.5±0.5) mg/L<(3.5±0.2) mg/L<(0.5±0.2) mg/L. Under anoxic condition, the corrosion resistance was stronger, and dissolved oxygen could reduce the polarization resistance and promote the corrosion of sponge iron filler.