气隙膜蒸馏回收绿色氨水性能研究

Research on green aqueous ammonia recovery performance by air gap membrane distillation

回收沼液中的氨氮可实现低成本和低碳足迹的氮肥生产.理论上气隙膜蒸馏能以绿色氨水形式将沼液中氨氮加以回收,然而该方面的研究还较少.本文对气隙膜蒸馏以氨水形式回收沼液中氨氮的具体性能进行了研究.采用单因素实验分别研究了气隙厚度、进料温度、初始氨氮浓度和进料流速等因素对模拟沼液中氨氮回收效率的影响.结果表明氨通量和水通量均随着进料温度的增加而增加,随着气隙厚度的增加而降低.进料流速为90 mL/min时,氨氮分离因子和氨氮脱除率均为最高值.基于单因素实验结果,采用正交实验探究气隙膜蒸馏回收氨氮的最佳实验变量组合.结果表明,气隙厚度3 mm、进料温度54℃、初始氨氮浓度800 mg/L和进料流速90 mL/min是以氨氮分离因子为评价参数时的最佳实验变量组合.

Recovering ammonia nitrogen from biogas slurry enables low-cost nitrogen fertilizer production with a low-carbon footprint.In theory,air gap membrane distillation(AGMD)can recover ammonia from biogas slurry in the form of aqueous ammonia solution,but few study documented.This article proposes to explore the recovery performance of aqueous ammonia solution by AGMD.In the single-factor experiment,the influence of air gap thickness,feed temperature,initial total ammonia nitrogen(TAN)concentration,and feed velocity on the ammonia recovery performance from simulated biogas slurry were investigated respectively.The results showed that both ammonia flux and water flux increased with the increase in feed temperature and decreased with the increase in air gap thickness.When the optimal feed velocity was 90 mL/min,both the highest ammonia separation factor and ammonia removal efficiency were obtained.Based on the results of the single-factor experiment,the orthogonal experiment was used to explore the optimal parameters for ammonia recovery by AGMD.The experimental results showed that the optimal conditions were the air gap thickness of 3 mm,the feed temperature of 54 C,the initial TAN of 800 mg/L,and the feed velocity of 90 mL/min,wherein the ammonia separation factor was used as the evaluation parameter.