Computer-aided process design, economic evaluation and environmental impact assessment for treatment of cheese whey wastewater

Efficient software was used for the comparison of five alternative scenarios for the treatment of cheese whey wastewater resulting from a Cheddar cheese factory. Scenario 1 deals with a cheese whey wastewater treatment plant that produces butter, whey protein concentrate and food-grade ethanol. In scenario 2 the butter-making section is similar to the basic process (scenario 1) with some differences in the concentration of whey proteins and in the removal of residual minerals from water. In scenario 3 the plant produces Manouri (a type of cream cheese) instead of butter. In scenario 4 the plant produces two types of whey protein concentrate (WPC), namely, a rich in whey lipids (WPC 2) and the other a highly purified protein concentrate possessing improved functional properties (WPC 1). In addition a process that produces pure lactose has replaced the ethanol section. In scenario 5 the plant produces butter, whey protein isolate (WPI) containing 95% protein and hydrolyzed-isomerized whey permeate syrup (HIPS). The economic comparison has shown that scenario 3 is the most profitable due to its high net present value (NPV) and low payback period as well as to its low production rate (40% of the full production rate) at the breakeven point. The environmental impact assessment demonstrated that scenario 4 is more environmentally friendly than the others due to the absence of biomass in the effluent.