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

Abstract

Meat rendering operations produce stick water waste which is rich in proteins, fats, and minerals. Membrane distillation (MD) may further recover water and valuable solids, but hydrophobic membranes are contaminated by the fats. Here, commercial hydrophobic polytetrafluorethylene (PTFE) membranes with a hydrophilic polyurethane surface layer (PU-PTFE) are used for the first time for direct contact MD (DCMD) on real poultry, fish, and bovine stick waters. Metal membrane microfiltration (MMF) was also used to capture fats prior to MD. Although the standard hydrophobic PTFE membranes failed rapidly, PU-PTFE membranes effectively processed all stick water samples to colourless permeate with sodium rejections >99%. Initial clean solution fluxes 5–6 L/m2/h declined to less than half during short 40% water recovery tests for all stick water samples. Fish stick water uniquely showed reduced fouling and up to 78% water recovery. Lost flux was easily restored by rinsing the membrane with clean water. MMF prior to MD removed 92% of fats, facilitating superior MD performance. Differences in fouling between stick waters were attributed to temperature polarisation from higher melt temperature fats and relative proportions to proteins. Hydrophilic coated MD membranes are applicable to stick water processing but further studies should consider membrane cleaning and longer-term stability.

Short Review on Porous Metal Membranes—Fabrication, Commercial Products, and Applications

“…Metal membranes have been studied for their filtration in a number of water applications such as drinking water treatment [ 10 , 21 ], rainwater purification [ 114 , 115 ], wastewater reclamation [ 11 ], and the treatment of wastewater from industries (e.g., meat processing) [ 116 ]. Leiknes and co-workers [ 10 , 21 ] studied the feasibility and potential of using microfiltration metal membranes (pore size 0.2 µm, Hitachi Metal Ltd., Tokyo, Japan) in a submerged membrane configuration with coagulation pre-treatment for producing drinking water.…”

“…Most recently, metal membrane filtration (MMF) was used to remove fats and COD from wastewater from meat rendering operations as pre-treatment for membrane distillation (MD) [ 116 ]. Meat processing produces stick water containing high amounts of fats and proteins that foul and wet hydrophobic polymeric MD membranes.…”

Membrane Distillation Trial on Textile Wastewater Containing Surfactants Using Hydrophobic and Hydrophilic-Coated Polytetrafluoroethylene (PTFE) Membranes

“…This commercial material is, therefore, an ideal candidate for the treatment of textile wastewaters rich in surfactants, and potentially fats and oils. The resistance to fats and oils by this membrane was demonstrated in previous work exploring the viability of MD applied in the meat industry [ 14 ].…”

Separation of saline oily wastewater by membrane distillation

“…However, a very low surface energy of these membranes accelerates the membrane wetting when the hydrophobic contaminants will be present in the feed water. Therefore, the new composite hydrophilic/hydrophobic membranes or membranes with amphiphobic surfaces were proposed for desalination of this type of feed (Guo et al 2015;Hou et al 2018;Lin et al 2014Lin et al , 2015Mostafa et al 2017;Rezaeia et al 2017). Unfortunately, the relatively high costs of proposed new membranes are expected to be problematic, because the industrial breakthrough of the contactors technology requires a high performance and inexpensive membranes (Eykens et al 2017(Eykens et al , 2018.…”