Effect of Morphological Structure of Polymeric Foams on the Mitigation of Organic Contaminated Water Pavani Cherukupally, Krishna Prasad Nagarajan Ramani, Amy M. Bilton, and Chul B. Park * University of Toronto, Toronto, Canada *Corresponding author:
[email protected] Background and Motivation The global water demand for agriculture, industrial processes, and domestic use is growing rapidly. Unfortunately, the available water resources are becoming increasingly scarce [1]. As a result, much research is currently focused on developing energy-efficient treatment of industrial wastewater such as oil sands tailings for reuse, energy generation, and product recovery [2]. For wastewater treatment, adsorbents in a fixed-bed configuration are widely used due to their efficacy, simplicity, and energy efficiency [3]. To advance the bed performance, this research is investigating a new class of adsorbent materials polymer foams for treatment of difficult-toremove emulsified organic compounds from oil field water. For practical implementation, the adsorbent has been configured in a lab-scale fixed-bed adsorbent filter (AF). However, this lab-scale system far away from commercial implementation. A key challenge is understanding of the complex phenomena governing the oil adsorption and accurately describing it in a computational model to enable system design. This paper describes a computational approach using COMSOL Multiphysics v. 5.2 to model and predict the performance of the foam based AF. Approach The goal of this work is to produce a generic model to enable an understanding of the physical, chemical, and electrical parameters of involved in the adsorption process. This model will be used to be able to identify parameters of a AF system shown in Fig. 1. In addition, the model will be used in design optimization studies and to extend the AF concept for other applications. This paper describes the preliminary AF model that has been developed.
Figure 1. Hybrid Electrochemical and adsorbent filtration lab-scale system for emulsified oilwater separation
The AF model shown in Fig. 1 developed in COMSOL consists of stationary porous foam fixedbed and mobile emulsified oily water. To model the adsorption process, the COMSOL-based framework outlined in Fig.2 was utilized. The coupled mass, energy, and momentum equations were solved numerically using the finite element method in COMSOL Multiphysics. In the preliminary simulations, the COMSOL built in adsorption model for mass transfer in porous adsorbent was used assuming instantaneous equilibrium between foam and oil, thereby neglecting mass transfer resistance. In future models, this resistance will be incorporated into the mass transport model. The mass transport model is coupled with built-in energy and momentum models predict the performance of the AF.
Figure 2. Model framework for investigating foam adsorbent filtration system using COMSOL Multiphysics
Preliminary Results Fig. 3 and 4 shows preliminary model results evaluating the pressure drop for different AF bed configurations and the oil adsorption isotherms, respectively. For the lab-scale system, the segmented bed leads to lower pressure drop of 0.8 PSI and a higher oil mass uptake due to lower resistance forces. These preliminary results have already provided insight in design and the more detailed future studies will use the model to optimize the overall AF configuration.
Figure 3. Pressure drops in continuous bed (left) and segmented bed (right)
Figure 4. Oil droplets mass uptake in continuous and segmented beds
Conclusions This paper presents preliminary models and lays the foundation towards design and development of foam based adsorbent filters. The approach can be used to evaluate AF for many applications including oily wastewater treatment, heavy metals removal, produced water treatment, and other separation processes.
References 1. M.A. Shannon et.al., Science and technology for water purification in the coming decades, Nature, 452, 301–310 (2008). 2. C.W. King and M.E. Webber, Water intensity of transportation. Environmental Science & Technology, 42, 7866−7872 (2008). 3. A. Fakhru’l-Razi et.al., Review of technologies for oil and gas produced water treatment, Journal of Hazardous Materials, 170, 530-551 (2009). 4. Tefera, Dereje Tamiru, et al., Two-dimensional modeling of volatile organic compounds adsorption onto beaded activated carbon, Environmental science & technology 47.20, 1170011710 (2013).
