Direct contact membrane distillation for the concentration of saline dairy effluent. (15th September 2015)

• Record Type: Journal Article
• Authors: Kezia, Kezia; Lee, Judy; Weeks, Mike; Kentish, Sandra
• Is Part Of: Water research. Volume 81(2015)
• Page Start: 167
• Page End: 177
• Publication Date: 2015-09-15
• Subjects: Membrane distillation -- Dairy salts -- Pressure drop -- Fouling; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2015.05.042
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: The ability of direct contact membrane distillation to concentrate the waste effluent from salty whey, a by-product from the cheese making industry has been investigated. The effect of trace protein in the feed, cross-flow velocity and feed acidity were the factors examined. Flat Sheet PTFE membranes of nominal pore sizes 0.05, 0.22 and 0.45 μm were utilised. A decline in feed flux in the presence of trace protein in the feed was observed, but liquid penetration through the membrane could still be prevented by utilization of a membrane of smaller pore size, to achieve a final total solids concentration of ±30% w/w with water recovery from 37 to 83 %. The pressure-drop across the channel length was also predicted accounting for the feed spacer. To increase the channel length up to 1 m will require operation using the smallest pore size of 0.05 μm, unless very low cross-flow velocities are used. The fouling of the membrane is primarily governed by precipitation of a calcium phosphate salt. However, operation at low pH does not improve the flux or the final salt concentration significantly. Graphical abstract: Highlights: Membrane distillation achieved 30 wt% solids and 37–83% water recovery. Trace protein reduced flux and caused liquid breakthrough. Membrane of 0.05 micron pore size needed for industrial scale operation. Acidification reduced calcium scaling but did not affect final salt concentration.