ABSTRACT
In recent years, membrane distillation (MD) has become a potentially promising membrane technology for desalination, water reuse, and wastewater treatment applications, especially in the fields of high-salinity waters, brackish water, and brine treatment, where separation and purification become economically and technically complex through the existing separation technologies (e.g., reverse osmosis (RO), electrodialysis (ED), as well as thermal processes including multistage flash (MSF) and multieffect distillation (MED)) (Al-Obaidani et al., 2008; Hanemaaijer et al., 2006). Through such attractive features and benefits, for a long period MD has become a targeted topic and examined by membrane researchers and scientists globally in different aspects, that is, development of membrane materials (Eykens et al., 2016a; Wang and Chung, 2015), membrane transport mechanisms (Phattaranawik and Jiraratananon, 2001; Yun et al., 2006), wetting phenomena (Rezaei et al., 2018), operation and process design (Francis et al., 2013; Lawson and Lloyd, 1996; Singh and Sirkar, 2012), and cost and energy evaluation (Al-Obaidani et al., 2008; Hogan et al., 1991). Recently, there have been positive progresses through increased interests from both academic and industry sectors on MD development and commercialization; commencing from the early 2000s, several commercially orientated R&D activities such as MD pilots and demonstration plants have been undertaken by research institutions, private and government-granted firms/startups (Drioli et al., 2015; Thomas et al., 2017). However, practical implementations on large full-scale MD plants have not yet been achieved.
