Recent advances and emerging trends in the utilization of dairy by-products/wastes

The dairy industry generates million of tons of by-products and wastes every year, mainly in the form of whey and wastewater. These by-products/wastes are typically high in nutrients, and organic and inorganic matter that possess a real threat to the environment and ecosystems. Direct release of these by-products may cause the excessive growth of microorganisms and aquatic plants which can dramatically deplete the dissolved oxygen and eventually form a dead zone. Some sustainable treatments such as using wetland, biological nutrient removal, and physicochemical methods are the most common solutions currently used by the dairy industries. However, not all dairy industries can implement effective waste management methods due to the high energy consumption, inefficient operation, and increasing maintenance costs. Therefore the transformation of dairy by-products/wastes into other valuable substances has been suggested as an alternative solution. Recently, biotechnological methods with the aid of bacteria, fungi, and algae have received increased interest due to their excellent efficiency and specificity, as well as being more eco-friendly. Through these approaches, dairy by-products/wastes have been proven to have great potential in producing bioplastics, exopolysaccharides, biofuels, organic acids, bioactive peptides, single-cell proteins, and biosurfactants.