A pilot scale study on the concentration of milk and whey by forward osmosis

Abstract

The concentration of skim milk and whey was investigated at a pilot scale using forward osmosis membranes with an installed membrane area of 24 m 2 . The pilot plant was operated in batch mode using a draw solution (48-57 g/L of NaCl) that mimics the potential brine streams available in a dairy processing plant. This approach avoids or limits the need for the regeneration of a synthetic draw solution. A concentration factor of ~2.5 was achieved for both the skim milk and fresh whey, resulting in a total solids concentration of ~21 wt% and 15 wt%, respectively. Increasing the transmembrane pressure was found to be effective in improving the water flux, whereas a much greater increase in the draw solution osmotic pressure would be needed to achieve the same enhancement of flux. This study also showed that small organic molecules, such as lactose, were not fully rejected by the forward osmosis membranes. A cleaning protocol was established for recovering the membrane performance after milk and whey concentration. The specific energy required for milk and whey concentration using only the forward osmosis step (5 -10 kWh/t water removed) is much lower than that required by reverse osmosis. Forward osmosis is an energy efficient and effective process for dairy applications if unlimited access to a brine stream can be made available within or in the proximity of dairy processing plants.

Role of Operating Conditions in a Pilot Scale Investigation of Hollow Fiber Forward Osmosis Membrane Modules

“…Pressure-less operation results in a unique process with a low fouling propensity [1], a high rejection of solutes [2], and low energy consumption [3]. Osmotically driven membrane processes have been intensively studied for decades in academia, but it was not until recently that progress in commercialization of this technology has manifested through multiple industrial applications of commercial FO membranes in pilot and full-scale installations (e.g., [4,5,6,7,8,9]). Due to the relatively early stage of this technology’s development, FO membranes with diverse form factors can be found on the market.…”

Forward Osmosis as Concentration Process: Review of Opportunities and Challenges

“…Only one FO study dedicated to skim milk concentration was reported. In that study performed on an 8´´ pilot scale setup, the concentration objective of 2.5 fold was achieved (from 8 to 21% wt) [ 62 ], proving the feasibility to concentrate milk using FO. The passage of small organic molecules was detected, which caused foaming in the draw solution during the concentration process.…”

“…Wang et al, using in-house made TFC HF membranes, also reached 22% dry solids whey thanks to a CF of 3.6 [ 66 ]. Chen et al evaluated whey concentration potential by FO, reaching a CF of 2.5 times and without significant change in dry product composition [ 62 ]. This study also pointed out that significant energy savings can be achieved using FO instead of thermal processes or (standalone) RO.…”

Microtechnological Tools to Achieve Sustainable Food Processes, Products, and Ingredients

“…Worldwide, more than 300,000 m 2 are installed for food processing, and of that 40% is used in dairy [51]. Among others, the following applications have been reported [114], here arranged based on pore size of the membrane: Lately, also forward osmosis [21,148] and thermo-dialysis [46,47] have been suggested for concentration purposes of dairy stream such as milk and whey, leading to water removal at low energy input. For more information on water treatment by reverse osmosis, which is also very important for food production, the interested reader is referred through to a recent review [5].…”