Waste water ammonia stripping intensification using microfluidic system

This paper reports the results of experimental removal process of ammonia from synthetically prepared ammonia solution using a microscale mixing loop air stripper. Effects of various operational parameters (such as pH, air flow rate, wastewater flow rate, and initial ammonia concentration) were evaluated. By increasing pH from 10 to 12.25, the amount of KLa increased from 0.26 to 0.73 h^-1. Considerable enhancement, about 150 %, can be found for KLa by changing the air flow rate from 280 to 700 mL/min under a fixed condition. The wastewater flow rate can also increase the value of KLa from 0.22 to 0.59 h^-1. The values of KLa increased only about 20 %by changing the initial concentration of ammonia in the range between 50 and 500 mg/L. The results showed that any improvement concerning air stripping using microchannel was successfully carried out with enhancing the overall volumetric mass transfer coefficient (KLa) and providing higher mass transfer capabilities compared with other types of strippers, even for lower amounts of used air. The enhancement of mass transfer takes place by efficient mixing induced by the employed microchannel. It has been demonstrated that wastewater flow rate and air flow rate have significant effects on KLa. The optimal stripping conditions and mathematical modeling for ammonia removal and the relation between the parameters were determined using Response Surface Methodology (RSM) with Central Composite Design (CCD) method. The results demonstrate the advantages the proposed system possesses over conventional stripper types.