Abstract：
Ammonia recovery from wastewater has positive environmental benefits, avoiding eutrophication and reducing production energy consumption, which is one of the most effective ways to manage nutrients in wastewater. Specifically, ammonia recovery by membrane distillation has been gradually adopted due to its excellent separation properties for volatile substances. However, the global optimization of direct contact membrane distillation (DCMD) operating parameters to maximize ammonia recovery efficiency (ARE) has not been attempted. In this work, three key operating factors affecting ammonia recovery, i.e., feed ammonia concentration, feed pH, and DCMD running time, were identified from eight factors, by a two-level Plackett-Burman Design (PBD). Subsequently, Box-Behnken design (BBD) under the response surface methodology (RSM) was used to model and optimize the significant operating parameters affecting the recovery of ammonia though DCMD identified by PBD and statistically verified by analysis of variance (ANOVA). Results showed that the model had a high coefficient of determination value (R2 = 0.99), and the interaction between NH4Cl concentration and feed pH had a significant effect on ARE. The optimal operating parameters of DCMD as follows: NH4Cl concentration of 0.46 g/L, feed pH of 10.6, DCMD running time of 11.3 h, and the maximum value of ARE was 98.46%. Under the optimized conditions, ARE reached up to 98.72%, which matched the predicted value and verified the validity and reliability of the model for the optimization of ammonia recovery by DCMD process.
摘要：
从废水中回收氨具有积极的环境效益，避免富营养化，降低生产能耗，这是管理废水中养分的最有效方法之一。具体来说,膜蒸馏法回收氨由于其对挥发性物质的优良分离性能而逐渐被采用。然而,没有尝试对直接接触膜蒸馏（DCMD）操作参数进行全局优化以最大化氨回收效率（ARE）。在这项工作中,影响氨回收的三个关键操作因素，即，进料氨浓度，饲料pH值,和DCMD运行时间，从八个因素中确定，由两级Plackett-Burman设计（PBD）。随后，响应面法（RSM）下的Box-Behnken设计（BBD）用于建模和优化影响氨回收率的重要操作参数，尽管通过PBD识别DCMD并通过方差分析（ANOVA）进行统计验证。结果表明，该模型具有较高的确定系数（R2=0.99），NH4Cl浓度与饲料pH的交互作用对ARE有显著影响。DCMD的最佳操作参数如下：NH4Cl浓度为0.46g/L，进料pH为10.6，DCMD运行时间为11.3h，ARE的最大值为98.46%。在优化条件下,达到98.72%，与预测值匹配,验证了DCMD工艺氨回收优化模型的有效性和可靠性。
