In this fourth article, of a four-part series, a patented process based on the concepts of membrane distillation (MD) and liquid-phase precipitation (LPP) for selective removal of sulfate from seawater is provided. The MD-LPP process uses a small amount of energy and additive, generates minimal waste with suitable disposal paths, extracts economic values from discarded streams or species, and offers a rapid economic deployment. Innovative approaches to integrate pressure-driven membranes such as nanofiltration (NF) and reverse osmosis (RO) in conjunction with LPP or compressed-phase precipitation (CPP) to mainly solve their inherent sulfate scale problems in treating seawater and the generation of large concentrate stream are also discussed.