Introduction to Membrane Distillation and Its Application in Emerging Contaminants Removal

Emerging contaminants (ECs) have huge impacts on all living beings, and conventional treatment processes like coagulation, precipitation, and chlorination have limited capability for removal. So, a tertiary and combined treatment process is required. Alternative treatment technologies include adsorption, chemical treatment, and membrane filtration. However, the associated operating cost, ECs rejection, fouling propensity, and by-product formation are some of the drawbacks. Membrane distillation (MD) is one of the promising membrane technologies for emerging contaminants removal. In MD, The vapor pressure difference between the hot feed and cold permeate is a driving force. MD technology has some added advantages like low-pressure requirements, less fouling susceptibility, low-temperature requirements, and only vapor mass transfer, i.e., 100% non-volatile compounds retention. MD employs a low temperature and pressure so fouling is less compact and is easily cleanable. MD technology has been studied for desalination, hypersaline brine treatment, chemical separation and can potentially remove emerging contaminants. The MD technology does not require very high-quality heat; solar heat, waste heat, or cogeneration-based heat utilization is possible. This way, MD can be operated on renewable energy and becomes sustainable and carbon neutral. MD technology has also been integrated with other efficient treatment technologies like Forward Osmosis (FO), Reverse osmosis (RO), and Nanofiltration (NF), providing a leading edge compared to other treatment methods. This chapter elaborates on various available MD technologies, possible materials, configurations, operating parameters, and energy requirements. We have also highlighted future research trends and challenges for MD treatment technology’s sustainable and commercial application.