Zou Yulong,Zhao Haiqian,Zhang Xiaolong,Wang Zhonghua,Yang Xue,Zhang Xing
View large Download slide View large Download slide Close modal The mechanism of phenol degradation by micro-electrolytic systems can be fully understood by evaluating the oxidation of active substances from the two aspects of phenol bond-breaking and mineralization, and the direction of promoting the generation of active substances is pointed out. In this article, the effects of H 2 O 2 , O 2 -• , ·OH and 1 O 2 in the degradation of phenol were analyzed using phenol and chemical oxygen demand (COD) removal rates as judgment indicators, respectively. And the addition of C 6 O 8 H 6 to the micro-electrolysis system was adopted to promote the generation of active substances. The experimental results showed that the active substances which played a dominant effect in the process of phenol bond-breaking and mineralization were changed. While 1 O 2 is dominant in the bond-breaking of phenol, •OH is dominant in the mineralization of phenol. After adding C 6 O 8 H 6 (1 mmol/L), the removal rates of phenol and COD were increased by 7.35 and 4.85%, respectively. This was attributed to the autoxidation reaction of C 6 O 8 H 6 and the continuous supply of H + while reducing Fe 3+ to Fe 2+ . Additionally, the C 6 O 8 H 6 regulated the reaction pathway to improve the utilization of H 2 O 2 . This study provides a new perspective for the understanding of active substances in micro-electrolysis systems. The main active substances in the bond-breaking and mineralization are different. is the main active substance in the phenol bond-breaking process. •OH is the main active substance in the phenol mineralization process. C 6 O 8 H 6 can promote the formation of active substances in the system. C 6 O 8 H 6 can promote the Fe 2+ /Fe 3+ cycle and improve the utilization of •OH.
Yifan Liang,Zengrui Pan,Jianlong Sheng,Yongjiong Ni,Jun Li
To enhance nitrogen removal in wastewater treatment , a novel method of wrapping waste iron shavings (Fe-C) in polyurethane sponge cubes tied in anoxic zones of a continuous reactor was proposed. Three types of denitrifying bacteria were enriched simultaneously in biofilms and activated sludge , including iron autotrophic denitrifying bacteria (7.83–8.71 %), heterotrophic denitrifying bacteria (10.60–11.95 %), and heterotrophic nitrification-aerobic denitrifying bacteria (23.47–40.06 %). Iron autotrophic denitrifying bacteria ( Dechloromonas and Sphaerotilus ) can remove NO 3 − -N using Fe 2+ as electron donor produced by micro-electrolysis of iron shavings without organic carbon demand, and heterotrophic nitrification-aerobic denitrifying bacteria ( Ferribacterium and Zoogloea ) can simultaneously accomplish nitrification and denitrification under aerobic conditions . The enrichment of these two functional bacteria strengthened the nitrogen removal performance compared to conventional heterotrophic denitrifying process, which could achieve efficient and stable total nitrogen removal (87.4 %) even with low organic carbon. In addition, the synergy of biological and chemical processes through Fe-C micro-electrolysis also enhanced total phosphorus removal (86.0 %).
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