响应面法优化超声吹脱处理香兰素生产废水中的氨氮工艺研究

Process optimization of ultrasonic stripping ammonia nitrogen in vanillin production wastewater using response surface method

为了提高废水中氨氮处理效率,采用响应面分析法对超声吹脱处理香兰素生产废水中的氨氮工艺条件进行优化,建立了吹脱时间、pH值、超声波功率及气液比4个关键因素与氨氮去除率之间的回归模型。结果表明,各影响因素对氨氮去除率影响程度由大到小依次为超声波功率、气液比、pH值、吹脱时间。确定对氨氮去除的最佳工艺条件为在超声功率90 W,超声吹脱时间90 min,pH值12、气液比600∶1的条件下,氨氮的去除率达到91.60%,与预测值接近,表明拟合度好。试验模型可以用来指导超声吹脱法处理废水中的氨氮。

The paper is aimed at presenting a response surface method in optimizing the processing conditions of ultrasonic stripping ammonia nitrogen from the sewage by relieving the vanillin sewage from the chemical plant in Wuhan,Hubei. For the said purpose,we have first of all developed a gas ultrasonic stripping device. With the said device,a single factor test has been conducted for the ammonia nitrogen adsorption at different rates under the different temperatures,stripping time,as well as the needed pH value,gas-liquid ratio,the ultrasonic power,along with the other conditions. The results of our testing experiments prove that,the critical influential factors for removing ammonia nitrogen are the ultrasonic power,the gas-liquid ratio,with the proper pH value and stripping time. Taking the said 4 critical factors for example,the response value should be taken as the key factors for the needed investigation at the ammonia nitrogen removal rate. In accordance with the Box-Behnken experimentdesigning principle,it is necessary to conduct regression analysis of the ammonia nitrogen removal rate,and adopt the simulated 4-factor and 3-level response surface to gain the prediction model of quadratic polynomial regression. And,then,the response surface diagram optimization results can help to reveal the significance order of each influential factor,that is,the ultrasonic power > the gas-liquid ratio > the pH value > the blowing time.Of them,the key factor should be the interaction between the ultrasonic power and the gas-liquid ratio. What is more,the model correction determination coefficient should be: Radj2= 0. 9719,and the regression term of the model is also of extremely great significance( p < 0. 0001),thus suggesting that the model is of high credibility and accuracy. And,combined with the actual operating conditions,it would be possible to determine the optimal process conditions as is shown below: the ultrasonic power is90 W,whereas the ultrasonic stripping time is 90 min with the pH value being 12 and gas-liquid ratio of 600: 1. On the above conditions,it would be possible for the removal rate of ammonia nitrogen to reach 91. 60%,which turns out to be basically consistent with the predicted value of the model theory. And,meanwhile,the simulation approach has also proven to be of a good predictability of the test results. And,in final analysis,the sewage through the ultrasonic stripping treatment can be said in a position to meet the demands of the ammonia nitrogen emission limitation of the provincial discharge standard of main water pollutants for chemical industry.