A hierarchical design procedure for membrane distillation crystallization processes based on a rigorous mathematical model and presented in a previous article is extended to address important aspects of this technology not yet discussed. The possibility of pore blockage due to premature crystallization inside the membrane distillation module is analyzed, and additional design criteria based on solubility curve shapes and metastable zone limit widths are established. An alternative process configuration is proposed for the treatment of dilute feeds in order to take advantage of the higher transmembrane fluxes characteristic of low-concentration solutions.