| Ultrafiltration (UF) and reverse osmosis (RO) membrane processes are attractive as isolation, concentration, and fractionation techniques for solutes found in natural and treated waters. This thesis describes the design specification and evaluation of a pilot scale spiral-wound UF and RO membrane unit.; The UF and RO membranes were characterized by evaluating the separation and sorption of a series of solutes at varying pH and pressure. Membrane integrity and stability were monitored based on hydraulic and solute permeability.; The UF membrane was evaluated using polymers, dyes, and tannins. The tannins, tannic acid and rutin, were selected as surrogate probes for natural aquatic humic materials. The results indicate that UF separation is not dictated by a simple sieving mechanism. UF recovery of tannic acid, but not rutin, is controlled by pH-dependent solute membrane interactions. Dextran polymers are useful for monitoring the membrane integrity.; The first non-cellulosic RO membrane showed superior separation, gradual decline, and membrane failure. The second modified polyamide RO membrane (FT-30) was characterized using polar organic RO probes, tannins, and inorganic ions. Solute separation and sorption characteristics with varying pH and pressure were evaluated.; The RO (FT-30) membrane showed consistently very high rejections for most solutes. The rejection results for the hydronium and inorganic ions indicates that low conductivity rejection below pH 3 is caused by both proton and counter ion (chloride) permeation. Rejection must be based on complete charge and mass balances. Both tannic acid and rutin RO recovery was complete, with no sorption effects.; In conclusion, pilot scale small-pore noninteractive type membranes are seen as offering advantages for organic solute and humic substance processing by overcoming phase and pH induced solute lability and degradation encountered in alternate isolation and concentration techniques. |
