Computational and experimental study for the desalination of petrochemical industrial effluents using direct contact membrane distillation

Muhammad S Osman,Adnan M Abu-Mahfouz,Vhahangwele Masindi

doi:10.1007/s13201-019-0910-3

Abstract

The petrochemical, mining and power industries have reacted to the recent South African water crisis by focussing on improved brine treatment for water and salt recovery with the aim of achieving zero liquid effluent discharge. The purpose of this novel study was to compare experimentally obtained results from the treatment of synthetic NaCl solutions and petrochemical industrial brines such as spent ion exchange regenerant brines and reverse osmosis (RO) brines to the classical well-known Knudsen diffusion, molecular diffusion and transition predictive models. The predictive models were numerically solved using a developed mathematical algorithm that was coded using MATLAB® software. The impact of experimentally varying the inlet feed temperature on process performance of the system is presented here and compared to simulated results. It was found that there was good agreement between the experimentally obtained results, for both the synthetic NaCl solution and the industrial brines. The mean average percentage error (MAPE) was found to be 7.9% for the synthetic NaCl solutions when compared to the Knudsen model. The Knudsen/molecular diffusion transition theoretical model best predicted the performance of the membrane for the industrial spent ion exchange regenerant brine with a mean absolute percentage error (MAPE) of 13.3%. The Knudsen model best predicted the performance of the membrane (MAPE of 10.5%) for the industrial RO brine. Overall, the models were able to successfully predict the water flux and can be used as potential process design tools.

Highlights

Brine treatment and disposal pose serious challenges for industries the petrochemical, mining and power industries
The direct contact membrane distillation (DCMD) process successfully treated spent ion exchange regenerant and reverse osmosis (RO) brines obtained from a petrochemical factory
The experimental results obtained were compared to the classical well-known Knudsen, molecular diffusion and transition predictive models, which were coded in MATLAB

Summary

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P Vapour pressure (Pa) pmf Vapour pressure at the feed membrane interface (Pa) pmp Vapour pressure at the permeate membrane interface (Pa). Pa Partial pressure of air in membrane pores (Pa) qf Feed flow qp Permeate rate flow ( ml rate min−1) ( ml min−1). Qf Feed side convective heat flux ( W m−2) Qm Conductive heat flux through the membrane ( W m−2). Tf Feed side inlet temperature (K) Tm Average temperature across the membrane (K). AGMD Air gap membrane distillation CSIR Council for Scientific and Industrial Research C&PUW Condensate and pickup water DCMD Direct contact membrane distillation EDR Electrodialysis reversal FO Forward osmosis IX Ion exchange MAPE Mean average percentage error MD Membrane distillation RO Reverse osmosis SGMD Sweeping gas membrane distillation TDS Total dissolved solids TOC Total organic carbon VEDCMD Vacuum-enhanced direct contact membrane distillation VMD Vacuum membrane distillation

Introduction

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Conclusions