High-nitrogen/phosphorus and low-C/N sewage treatment by iron-scarps and Ti(RuO2) based three-dimension electrode
DING Hong1,,, WANG Yijie1, WU Fuping2 1.Bowen College, Lanzhou Jiaotong University, Lanzhou 730101, China 2.School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
Abstract:The high nitrogen/phosphorus and low C/N ratio sewage is more and more common, the development of the corresponding treatment technology is of significant importance. In this study, iron-scrap was used to set up the iron-scarp (IS) based Ti(RuO2)-three-dimension electrode (IS-TDE) for the practical high nitrogen/phosphorus and low C/N ratio sewage treatment. The impacts of IS dosage, reaction time and cell voltage on electric oxidation efficiency were investigated, as well as the catalytic effect of Cl? on $ {\rm{NH}}_4^ + $-N oxidation. The kinetics was also analyzed. The addition of IS at volume ratio of 30% could improve the removal rates of $ {\rm{NH}}_4^ + $-N, TN and TP by 31.8%, 41.3% and 79.8%, respectively. The addition of IS improved the efficiency of electro-oxidation of IS-TDE and $ {\rm{PO}}_4^ {3-} $ precipitation with Fe3+ occurred. The optimal react time and cell voltage were 80 min and 10 V, respectively. Cl? addition initiated the production of Cl2 and HClO in IS-TDE which oxidized $ {\rm{NH}}_4^ + $-N into N2, and significantly reduced $ {\rm{NO}}_3^ {-} $-N and $ {\rm{NO}}_2^ {-} $-N accumulation. When the optimal molar ratio of Cl? and $ {\rm{NH}}_4^ + $-N was 4, TN removal rate constant (k) increased from 0.27 min?1 to 0.69 min?1. The removal rates of $ {\rm{NH}}_4^ + $-N, TN and TP were 96.8%, 93.4% and 98.1%, respectively. The present research provided a theoretic basis and technical support for efficient treatment of high nitrogen/phosphorus and low C/N ratio sewage. Key words:iron-scrap and Ti(RuO2) based three-dimension electrode/ low C/N ratio wastewater/ chlorine ion (Cl-)/ nitrogen and phosphorus removal/ kinetics.
图2铁屑投加量(体积分数)对废铁屑-Ti(RuO2)三维电极去除$ {\rm{NH}}_4^ + $-N和TP的影响 Figure2.Impact of iron-scrap dosage (volume percentage) on $ {\rm{NH}}_4^ + $-N and TP removal by the iron-scarp based Ti(RuO2)-three-dimension electrode
图3不同铁屑投加量(体积分数)下$ {\bf{NO}}_3^ {-} $-N和$ {\bf{NO}}_2^ {-} $-N的积累及TN的去除 Figure3.$ {\rm{NO}}_3^ {-} $-N and $ {\rm{NO}}_2^ {-} $-N accumulation and TN removal by the iron-scarp based Ti(RuO2)-three-dimension electrode at different iron-scrap dosages (volume percentage)
图6Cl?的投加量(R)对废铁屑-Ti(RuO2)三维电极脱氮的影响 Figure6.Impact of Cl? dosage (R) on nitrogen removal performance of the iron-scarp based Ti(RuO2)-three-dimension electrode
图7不同Cl?的投加量(R)下$ {\rm{NO}}_3^ {-} $-N和$ {\rm{NO}}_2^ {-} $-N的积累及TN的去除 Figure7.Impact of Cl? dosage (R) on $ {\rm{NO}}_3^ {-} $-N and $ {\rm{NO}}_2^ {-} $-N accumulation and TN removal by the iron-scarp based Ti(RuO2)-three-dimension electrode
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1.Bowen College, Lanzhou Jiaotong University, Lanzhou 730101, China 2.School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China Received Date: 2020-07-08 Accepted Date: 2020-10-16 Available Online: 2021-03-24 Keywords:iron-scrap and Ti(RuO2) based three-dimension electrode/ low C/N ratio wastewater/ chlorine ion (Cl-)/ nitrogen and phosphorus removal/ kinetics Abstract:The high nitrogen/phosphorus and low C/N ratio sewage is more and more common, the development of the corresponding treatment technology is of significant importance. In this study, iron-scrap was used to set up the iron-scarp (IS) based Ti(RuO2)-three-dimension electrode (IS-TDE) for the practical high nitrogen/phosphorus and low C/N ratio sewage treatment. The impacts of IS dosage, reaction time and cell voltage on electric oxidation efficiency were investigated, as well as the catalytic effect of Cl? on $ {\rm{NH}}_4^ + $-N oxidation. The kinetics was also analyzed. The addition of IS at volume ratio of 30% could improve the removal rates of $ {\rm{NH}}_4^ + $-N, TN and TP by 31.8%, 41.3% and 79.8%, respectively. The addition of IS improved the efficiency of electro-oxidation of IS-TDE and $ {\rm{PO}}_4^ {3-} $ precipitation with Fe3+ occurred. The optimal react time and cell voltage were 80 min and 10 V, respectively. Cl? addition initiated the production of Cl2 and HClO in IS-TDE which oxidized $ {\rm{NH}}_4^ + $-N into N2, and significantly reduced $ {\rm{NO}}_3^ {-} $-N and $ {\rm{NO}}_2^ {-} $-N accumulation. When the optimal molar ratio of Cl? and $ {\rm{NH}}_4^ + $-N was 4, TN removal rate constant (k) increased from 0.27 min?1 to 0.69 min?1. The removal rates of $ {\rm{NH}}_4^ + $-N, TN and TP were 96.8%, 93.4% and 98.1%, respectively. The present research provided a theoretic basis and technical support for efficient treatment of high nitrogen/phosphorus and low C/N ratio sewage.
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