Membrane-based enrichment of omega-3 fatty acids in fish oil: Techno-economic study

Concentrated ω3 fatty acids products represent an important support for their recommended intake in human diet. Several concentration routes exist nowadays, depending also on the desired enrichment level. One of the emerging solutions is the use of membranes, coupled with the enzymatic enrichment route. In this scenario, a lipase uses ethanol to selectively detach from the triglycerides short chain acids, leaving polyunsaturated fatty acids attached. Reaction mixture is then sent to a dense polymeric membrane, able to retain preferentially the enriched glycerides allowing ethyl esters to cross the membrane more easily. To assess the potential benefits of this innovative route, modelling activity is a fundamental support. In literature, several studies investigated solvent nanofiltration through membranes, although studies at process scale are still limited and this also limits the diffusion of membrane technology. In this work, both a kinetic and membrane section models are used to develop the process model of the system. A techno-economic analysis is performed to estimate the levelized cost of the enriched oil as function of the level of enrichment. Results are compared with a benchmark process based on a non-selective transesterification of the acids followed by molecular distillation. Membrane-based process is able to enrich the oil from 31.65% up to 54% (a factor 1.7), while the higher the enrichment, the more the oil input needed per unit of product, the higher the product cost. Considering as feedstock fish oil with a cost of 10 €/kg, the products cost ranges from 13 €/kg at low enrichment up to 33.2 €/kg at 1.7, outperforming the results of the benchmark solution (from 16.5 €/kg to 39.2 €/kg in the same range) and therefore assessing the potential gains in membranes’ application in this process.