Abstract
Dairy liquid by-products after cheese production (e.g. whey for hard cheese, “scotta” for ricotta, brine for mozzarella, lactose syrup after milk standardization by ultrafiltration) represent a potential revenue for food factories where large scale industrial production is implemented, as additional ingredients may be recovered, transformed and sold. Still, these by-products may also represent a problem for small/medium size factories or in areas that are far from ingredients transformation platforms: complete processing of small volumes or shipping liquids over long distances is not convenient. By-products are often disposed as waste, generating unproductive cost for the factory and worsening environmental footprint.
In this paper a simple closed loop solution is evaluated for full valorization of by-products, based on the technologies of protein separation/concentration and anaerobic treatment of the lactose solution.
Whey proteins are separated by ultrafiltration and can be reused in the cheese process or converted locally into fresh animal feed. Application studies will be presented.
Ultrafiltration permeate (filtrate) is a diluted lactose syrup that is used as raw material for fermentation. Lactose dark fermentation for hydrogen production has been documented on a laboratory scale, but not really tested before on a semi-industrial scale. Results obtained from both laboratory scale and semi-industrial scale fermenter will be presented. Finally, anaerobic membrane digester has been evaluated on a semi-industrial scale to convert all residual lactose into biomethane, that can be efficiently reused in the dairy factory boiler for steam production.
Anaerobic membrane digester proved to be a valuable solution, as it allows maximum lactose conversion efficiency with good quality liquid effluent.
