Direct contact membrane distillation for the concentration of saline dairy effluent

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.

Membrane Distillation of Meat Industry Effluent with Hydrophilic Polyurethane Coated Polytetrafluoroethylene Membranes

“…However, due to wetting, this slight pressure caused a reverse liquid flow exceeding forward distillation flux. The standard hydrophobic PTFE membrane was, therefore, not suitable for MD processing of stick water, however, approaches are being considered by researchers to minimise wetting, such as pore size on other available membrane types [ 36 ], or more novel developed materials [ 37 ]. The focus in our work is to explore hydrophilic PU-coated hydrophobic PTFE (PU-PTFE) as a means to prevent wetting.…”

High flux and antifouling properties of negatively charged membrane for dyeing wastewater treatment by membrane distillation

“…Continuous efforts by scientists and engineers have improved the effectiveness of membrane-based processes for the removal of color and toxicity (Alcaina-Miranda et al, 2009;Aouni et al, 2012;Han et al, 2009;Mo et al, 2008). In particular, membrane distillation (MD), an emerging membrane-based technology, has generated interest because it can achieve a high rejection rate under mild temperatures and normal atmospheric pressure (Alkhudhiri et al, 2012;Kezia et al, 2015;Liao et al, 2014;. MD uses a hydrophobic porous membrane to separate the hot feed stream and the cold stream (Elimelech, 2014), whose temperature difference creates a trans-membrane vapor pressure difference that drives the vapors from the hot side to the cold side through the membrane pores (Hassan and Fath, 2013;Woo et al, 2015).…”

Enhanced water desalination performance through hierarchically-structured ceramic membranes

“…According to the water vapor cooling-down method, the MD process can be classified into four different configurations [5]. By survey of the previous studies, it can be found that among these different MD processes, direct contact membrane distillation (DCMD) is the widely adopted configuration due to its simplicity and reasonably high water flux [32][33][34][35][36][37]. Therefore, in this study, DCMD configuration is used to evaluate the separation properties of the hydrophobic ceramic membranes prepared using the freeze drying tape casting method.…”