Selectivity of vacuum ammonia stripping using porous gas-permeable and dense pervaporation membranes under various hydraulic conditions and feed water compositions

Recovery of ammonia (NH3) from residual waters offers various reuse opportunities, such as the production fertilisers and generation electricity heat. However, simultaneous evaporation water (H2O) during NH3 stripping under vacuum results in diluted recovered gas with high H2O contents. Whereas porous gas-permeable membranes are already used for stripping, use non-porous silica-based pervaporation (PV) showed promising recent literature, respect to more selective transfer compared H2O. In this study, we assessed selectivity over (SNH3/H2O) different types membranes, hydraulic conditions feed compositions. The three following were tested: a polytetrafluoroethylene (PTFE) membrane, hydrophilic (Hybrid Silica PV) membrane hydrophobic polydimethylsiloxane PV (PDMS membrane. For PTFE Hybrid SNH3/H2O ranged between 0.1 0.4, indicating that was consistently less preferred preference through at compositions can be assigned similarity polarity kinetic diameter low relative concentration (approximately 0.1–1.0 wt%). PDMS negligible deteriorated rapidly experiments. both higher unsteady than steady conditions. Furthermore, decreased when ionic strength increased 0.0 0.8 mol∙L−1 1 10 g∙L−1. According results, did not show transfer. fact, had lower Hence, dense allow recovery gaseous water, content gas, membranes.