(71a) Process Feasibility and Evaluation of Vibratory Shear-Enhanced Nanofiltration As a Coffee Extract Pre-Concentration Alternative in Soluble Coffee Manufacturing

Thermal dewatering operations in soluble coffee manufacturing, like evaporation, are energy-intensive operations that contribute to the industry’s cost and environmental impacts. With the support of the U.S. Environmental Protection Agency, we have explored approaches to the intensification of soluble coffee production for Nestlé Beverage USA. Our past work has focused on water recovery from production waste streams using membrane processes. We are currently investigating methods to extend this approach in new directions. One study investigated a vibratory nanofiltration process as a less energy-intensive alternative to evaporation in the pre-concentration of coffee extract prior to spray- or freeze-drying. Such approach opens opportunities in the intensification of soluble coffee production in terms of energy efficiency, water recovery, and waste reduction, thereby reducing the carbon footprint of the overall operations. The dynamic vibratory filtration serves as one of the more recent technologies that can enhance the shear rates on membrane surface to reduce membrane fouling, typically limiting conventional crossflow separation. Results showed that increases the permeate flux to about three times higher than that observed in conventional crossflow filtration. The rejection of suspended (> 99.9%) and dissolved (> 90%) organics from the filtration of reconstituted coffee extracts was also found to recover permeate reusable for ancillary plant operations, thereby reducing wastewater generation. Process models are also used to demonstrate the effects of experimental conditions such as coffee extract concentration and bulk characteristics, pressure, vibrational amplitude, and surface shear rates on permeate flux, rejection efficiencies, and concentration polarization. Scale-up parameters and operating conditions obtained from laboratory investigation shall serve as bases for techno-economic and environmental impacts assessment. The potential energy savings, operating costs reduction, economic feasibility, and resulting life cycle emissions profiles of the scaled-up operation are also presented as criteria for sustainability. The study highlights the benefits and limitations of integrating vibratory membrane filtration in comparison with thermal evaporation to preconcentrate coffee extracts and its potential contribution to food-water-energy nexus for sustainable production.