Document Type : Full article


1 CFD research center, Chemical Engineering Department, Razi University, Kermanshah, Iran

2 CFD Research Center, Chemical Engineering Department, Razi University, Kermanshah, Iran


This paper reports the results of experimentally removing ammonia from synthetically prepared ammonia solution using a micro scale 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 the pH from 10 to 12.25 the amount of KLa increased from 0.26 to 0.73 hr-1. A considerable enhancement, about 150%, can be found for KLa by changing the air flow rate from 280 to 700 mL/min under fixed condition. The wastewater flow rate can also the value of KLa from 0.22 to 0.59 hr-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 improving in air stripping using microchannel was successfully carried out with enhancing 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 is happened 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 over convention stripper types.


Main Subjects

[1]      Değermenci, N., Ata, O. N. and Yildiz, E., “Ammonia removal by air stripping in a semi-batch jet loop reactor”, Ind. Eng. Chem., 18 (1), 399 (2012).
[2]      Bonmatı, A. and Flotats, X. , “Air stripping of ammonia from pig slurry: Characterisation and feasibility as a pre-or post-treatment to mesophilic anaerobic digestion”, Waste manag., 23 (3), 261 (2003).
[3]      Cheung, K. C., Chu, L. M. and Wong, M. H., “Ammonia stripping as a pretreatment for landfill leachate”, Water, Air, Soil Pollut., 94 (1-2), 209 (1997).
[4]      Minocha, V. K. and Rao, A. P., “Ammonia removal and recovery from urea fertilizer plant waste”, Environ. Technol., 9 (7), 655 (1988).
[5]      Bolado-Rodríguez, S., García-Sinovas, D. and Álvarez-Benedí, J., “Application of pig slurry to soils: Effect of air stripping treatment on nitrogen and TOC leaching”, J. Environ. Manage., 91 (12), 2594 (2010).
[6]      Quan, X., et al., “Simultaneous removal of ammonia, P and COD from anaerobically digested piggery wastewater using an integrated process of chemical precipitation and air stripping”, J. Hazard. Mater., 178 (1), 326 (2010).
[7]      Djebbar, Y. and Narbaitz, R., “Improved Onda correlations for mass transfer in packed towers”, Water Sci. Technol., 38 (6), 295 (1998).
[8]      Basakcilardan-Kabakci, S., Ipekoglu, A. N. and Talinli, I., “Recovery of ammonia from human urine by stripping and absorption”, Environ. Eng. Sci., 24 (5), 615 (2007).
[9]      Quan, X., et al., “Air stripping of ammonia in a water-sparged aerocyclone reactor”, J. Hazard. Mater., 170 (2), 983 (2009).
[10]  Cypes, S. H. and Engstrom, J., “Analysis of a toluene stripping process: A comparison between a microfabricated stripping column and a conventional packed tower”, Chem. Eng. J., 101 (1), 49 (2004).
[11]  Vankayala, B. K., et al., “Scale-up of process intensifying falling film microreactors to pilot production scale”, Int. J. Chem. Reactor Eng., 5 (1), Article A91, (2007).
[12]  Wenn, D. A., Shaw, J. E. and Mackenzie, B., “A mesh microcontactor for 2-phase reactions”, Lab on a Chip, 3 (3), 180 (2003).
[13]  Chambers, R. and Spink, R. H., “Microreactors for elemental fluorine”, Chem. Commun., 10, 883 (1999).
[14]  De Bellefon, C., et al., “Asymmetric catalytic hydrogenations at micro-litre scale in a helicoidal single channel falling film micro-reactor”, Catal. Today, 110 (1), 179 (2005).
[15]  Moschou, P., et al., “Nitrogen stripping of isopropyl-alcohol and toluene in a falling film micro reactor: Gas side mass transfer experiments and modelling at isothermal conditions”, Chem. Eng. Sci., 76, 216 (2012).
[16]  Sun, X., Constantinou, A. and Gavriilidis, A., “Stripping of acetone from isopropanol solution with membrane and mesh gas–liquid contactors”, Chem. Eng. Process., 50 (10), 991 (2011).
[17]  Almasvandi, M. H., Rahimi, M. and Tagheie, Y., “Microfluidic cold stripping of H2S from crude oil in low temperature and natural gas consumption”, J. Natural Gas Sci. Eng., 34, 499 (2016).
[18]  Zhang, X., Stefanick, S. and Villani, F. J., “Application of microreactor technology in process development”, Org. Process Res. Dev., 8 (3), 455 (2004).
[19]  Brandt, J. C. and Wirth, T., “Controlling hazardous chemicals in microreactors: Synthesis with iodine azide”, Beilstein J. Org. Chem., 5 (1), 30 (2009).
[20]  Sun, J., et al., “Synthesis of biodiesel in capillary microreactors”, Ind. Eng. Chem. Res., 47 (5), 1398 (2008).
[21]  Guan, G., et al., “Transesterification of sunflower oil with methanol in a microtube reactor”, Ind. Eng. Chem. Res., 48 (3), 1357 (2009).
[22]  Guan, G., et al., “Two‐phase flow behavior in microtube reactors during biodiesel production from waste cooking oil”, AIChE J., 56 (5), 1383 (2010).
[23]  Basiri, M., Rahimi, M. and Mohammadi, H. B., “Ultrasound-assisted biodiesel production in microreactors”, Iranian J. Chem. Eng., 13 (2), 23 (2016).
[24]  Mahjoob, M., Etemad, S. G. and Thibault, J., “Numerical study of non-newtonian flow through rectangularmicrochannels”, Iranian J. Chem. Eng., 6 (4), 45 (2009).
[25]  Niu, H., et al., “Flow pattern, pressure drop, and mass transfer in a gas- liquid concurrent two-phase flow microchannel reactor”, Ind. Eng. Chem. Res., 48 (3), 1621 (2008).
[26]  Chen, J. F., et al., “High‐throughput microporous tube‐in‐tube microreactor as novel gas–liquid contactor: Mass transfer study”, AIChE J., 57 (1), 239 (2011).
[27]  Su, H., et al., “Mass transfer characteristics of H2S absorption from gaseous mixture into methyldiethanolamine solution in a T-junction microchannel”, Sep. Purif. Technol., 72 (3), 326 (2010).
[28]  Bashir, M. J., et al., “Application of response surface methodology (RSM) for optimization of ammoniacal nitrogen removal from semi-aerobic landfill leachate using ion exchange resin”, Desalination, 254 (1), 154 (2010).
[29]  Kikutani, Y., et al., “Circulation microchannel for liquid–liquid microextraction”, Microchimica Acta, 164 (3-4), 241 (2009).
[30]  Hossini, H., et al., “Optimizing ammonia volatilization by air stripping from aquatic solutions using response surface methodology (RSM)”, Desalination and Water Treat., (ahead-of-print), 1 (2015).
[31]  Xu, J., et al., “Enhancement of mass transfer performance of liquid–liquid system by droplet flow in microchannels”, Chem. Eng. J., 141 (1), 242 (2008).
[32]  N. Kashid, M., Renken, A. and Kiwi-Minsker, L., “Influence of flow regime on mass transfer in different types of microchannels”, Ind. Eng. Chem. Res., 50 (11), 6906 (2011).
[33]  Boogar, R. S., Gheshlaghi, R. and Mahdavi, M. A., “The effects of viscosity, surface tension, and flow rate on gasoil-water flow pattern in microchannels”, Korean J. Chem. Eng., 30 (1), 45 (2013).
[34]  Rahimi, M., et al., “Optimization of biodiesel production from soybean oil in a microreactor”, Energy Convers. Manage., 79, 599 (2014).
[35]  Kumar, V., Paraschivoiu, M. and Nigam, K., “Single-phase fluid flow and mixing in microchannels”, Chem. Eng. Sci., 66 (7),1329 (2011).
[36]  Gaddis, E. and Vogelpohl, A., “The impinging-stream reactor: A high performance loop reactor for mass transfer controlled chemical reactions”, Chem. Eng. Sci., 47 (9), 2877 (1992).
[37]  Petruccioli, M., et al., “Aerobic treatment of winery wastewater using a jet-loop activated sludge reactor”, Process Biochem., 37 (8), 821 (2002).
[38]  Yildiz, E., et al., “High strength wastewater treatment in a jet loop membrane bioreactor: Kinetics and performance evaluation”, Chem. Eng. Sci., 60 (4), 1103 (2005).
[39]  Jain, D., et al., “Liquid circulation characteristics in jet loop reactors”, Can. J. Chem. Eng., 68 (6), 1047 (1990).
[40]  Amirkhani, L., Moghaddas, J. and Jafarizadeh-Malmiri, H., “Optimization of Candida rugosa Lipase immobilization parameters on magnetic silica aerogel using adsorption method”, Iranian J. Chem. Eng., 13 (3), (2016).
[41]  Doust, A. M., Rahimi, M. and Feyzi, M., “An optimization study by response surface methodology (RSM) on viscosity reduction of residue fuel oil exposed ultrasonic waves and solvent injection”, Iranian J. Chem. Eng., 13 (1), (2016).
[42]  Shafiee, M., et al., “Preparation of ultra high molecular weight polyethylene using Ziegler-Natta catalyst system: Optimization of parameters by response surface methodology”, Iranian J. Chem. Eng., 11 (1), (2014).
[43]  Wu, Y., Li, Q. and Li, F., “Desulfurization in the gas-continuous impinging stream gas–liquid reactor”, Chem. Eng. Sci., 62 (6), 1814 (2007).
[44]  Sawyer, C. and McCarty, P., Chemistry for environmental engineers, New York. Mc Graw-Hill Book Company, (1978).
[45]  Huang, J. C. and Shang, C., Air stripping, in Advanced physicochemical treatment processes, Springer, p. 47 (2006).
[46]  Design-Expert-Software,, Trial version, Last seen at 1 November, (2015).
[47]  Al-Shamrani, A., James, A. and Xiao, H.  “Separation of oil from water by dissolved air flotation”, Colloids Surf., A: Aspects, 209 (1), 15 (2002).
[48]  Körbahti, B. K. and Tanyolaç, A., “Electrochemical treatment of simulated textile wastewater with industrial components and Levafix Blue CA reactive dye: Optimization through response surface methodology”, J. Hazard. Mater., 151 (2), 422 (2008).
[49]  Ölmez, T., “The optimization of Cr (VI) reduction and removal by electrocoagulation using response surface methodology”, J. Hazard. Mater., 162 (2), 1371 (2009).
[50]  Joglekar, A. M., et al., “Product excellence through experimental design”, Food Product and Development: From Concept to the Marketplace, 211 (1987).
[51]  Myers, R. H., Montgomery, D. C. and Anderson-Cook, C. M., Response surface methodology: Process and product optimization using designed experiments, Vol. 705, John Wiley & Sons, (2009).