养殖水电化学同步脱氮响应面优化与验证

Optimization and validation of electrochemical technology for simultaneous nitrogen removal in aquaculture by using response surface methodology

中文关键词: 水产养殖  电化学技术  同步脱氮  响应面分析

英文关键词: Aquaculture  Electrochemical technology  Simultaneous nitrogen removal  Response surface methodology

中文摘要:

      本研究先通过单因子实验分析了电流密度、极板面积比、极板间距和初始pH对总氨氮(TAN)和硝态氮(NO3–-N)去除率的影响。采用Design-Expert软件中Box-Behnken的中心组合原则设计四因素三水平响应面实验，考察不同影响因子对脱氮效率的影响，并建立响应面模型优化反应条件，最后对优化的反应条件进行验证。结果显示，电流密度、极板面积比、极板间距和初始pH的变化对TAN去除影响不大，在所选反应条件下，TAN去除率均高于80%，但反应条件的改变显著影响硝酸盐(NO3)的去除，NO3去除率在29.8%~80.9%范围内变化。响应面模型的回归系数R2为0.9340，校正系数R2为0.8681，说明该模型具有较好的准确性。NO3去除最优反应条件：电流密度为25.6 mA/cm2，阴阳极板面积比为1.6∶1，极板间距为2.5 cm，初始pH为6.6，对该反应条件下的脱氮效果展开实验验证发现，TAN去除率为87.3%，NO3去除率为81.5%。研究表明，电化学处理可实现对TAN和NO3–-N的同步去除，同时，响应面模型的运用有助于优化电化学法在养殖水处理中的脱氮效率。

英文摘要:

      The simultaneous removal of ammonia and nitrate nitrogen is a challenging process in the treatment of recirculating aquaculture systems. This study first analyzed the effects of current density, plate area ratio, plate spacing, and initial pH on the removal rates of ammonia and nitrate nitrogen by a single-factor experiment. To understand the effects of different influencing factors on the efficiency of nitrogen removal, four-factor and three-level response surface experiments were designed on the basis of the central combination principle of Box-Behnken in Design-Expert software. Subsequently, the reaction conditions for the simultaneous removal of ammonia and nitrate nitrogen were optimized using a response surface model. Finally, the optimized reaction conditions were evaluated using verification experiments. In the single-factor experiments, we found that the changes in the current density, plate area ratio, plate spacing, and initial pH had little effect on ammonia and nitrate nitrogen removal. The removal rate of ammonia is always > 80% in the given reaction conditions, whereas the changes in reaction conditions significantly affected the removal rate of nitrate nitrogen, which ranges from 29.8% to 80.9%. The constructed response surface model showed that the regression coefficient (R2) was 0.9340 and the correction coefficient (R2) was 0.8681, which showed that the model has good accuracy. We obtained the optimal reaction conditions using the response surface model: current density was 25.6 mA/cm2, plate area ratio between cathode and anode was 1.6:1, plate spacing was 2.5 cm, and initial pH was 6.6. Experimental verification under the reaction conditions proved that the removal rate of nitrate nitrogen could reach up to 81.5% and the removal rate of ammonia up to 87.3%. This experiment showed that electrochemical treatment can effectively achieve the simultaneous removal of ammonia and nitrate nitrogen and that application of the response surface model can improve the nitrogen removal efficiency of electrochemical treatment in aquaculture wastewater.