A Simple Solution of Dissolved Ammonia Recovery Process in a Hollow-Fiber Membrane Contactor: Comparison with Experimental and Numerical Results

Md Monwar Hossain,O Chaalal,Eman W Hassan

doi:10.6000/1929-6037.2019.08.01

Abstract

Ammonia in gaseous form is one of the major pollutants in waters and wastewaters. Of all the processes studied so far for the removal of dissolved ammonia from aqueous solution, hollow fiber membrane contactor-based processes have shown great potential. This method has shown to be effective to substantially reducing ammonia concentration to an acceptable value economically and efficiently. Mathematical analysis is presented in this report for the removal of ammonia dissolved in an aqueous phase to a recovery/stripping solution in a hollow fiber membrane contactor (HFMC). The membrane contactor is considered to consist of the lumen side (allowing aqueous flow) and shell side (allowing the flow of the stripping/recovery solution). An approximate analytical solution is derived for the simplified model that does not include radial diffusion of solutes (only axial mass flux is included). The predicted results of this solution are compared with the experimental data and with the numerical results in the literature over a range of operating conditions. The flow rates of the feed solution covered: 2.01 x 10 -9 to 4.7 x 10 -6 m3/s, initial concentration: 50 – 800 ppm and pH values of the solution containing ammonia: 8 - 11. The agreement is very good between the profiles of the simplified analytical solution and the earlier published experimental data. In addition, the results obtained by the analytical solution are close to the numerical solution of the complete model over a good range of operating conditions.

Highlights

Several separation techniques have been developed to purify or clean wastewater solutions that are polluted with several pollutants such as, chemical, physical and other types
Ammonia in gaseous form is one of the major pollutants introduced into receiving natural waters by industrial, domestic and agricultural wastewater discharges that scientists are trying to get rid of it using different techniques
The ammonia concentration in the tank decreased exponentially as the contact time increased and attained 20% of the initial value within 100 minutes for all the concentrations tested in the experiment

Summary

Introduction

Several separation techniques have been developed to purify or clean wastewater solutions that are polluted with several pollutants such as, chemical, physical and other types. Ammonia in gaseous form is one of the major pollutants introduced into receiving natural waters by industrial, domestic and agricultural wastewater discharges that scientists are trying to get rid of it using different techniques This is because the accumulation of this pollutant results in depletion of oxygen due to nitrification and harms the waterborne organisms such as fish in addition to its toxicity. Various techniques have been studied for the removal of dissolved ammonia They include air stripping, break-point chlorination, chemical precipitation, selective ion exchange, biological nitrification, denitrification, biological nitrification and others [1,2,3,4]. These techniques have some drawbacks that let them not to be used. The disadvantages in break-point chlorination technique are: it requires large treatment volume, the pH is difficult to control and high

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