Utilization of whey

Abstract

Large amounts of wastewaters emerge from milk processing in dairies, which are one of the largest sources of industrial effluents. Thus, wastewater and organic residues produced from dairy production have the potential to be converted into economic gain if the proper processing technology is employed. Among others anaerobic digestion (AD) is a promising technology to gain economic benefits. The main advantage of AD is the production of biogas, a renewable energy source. A valuable effluent also is obtained, which mainly can be used as an excellent soil fertilizer. Most of wastewater in dairies results from cleaning and rinsing processes of transport lines, technical equipment, or tanks. Carbohydrates, fats, and proteins from milk are the main contributors of organic load. Modern companies lowered their use of fresh water and reduced the amount of wastewater. Separating organic residues of production processes from wastewater reduces the organic freight additionally. Due to this measure the average organic load ranges between 2.5 and 2.3 g COD=liter (COD-chemical oxygen demand). Nevertheless the average composition of dairy wastewater has a wide range concerning characteristic parameters, as shown in Table 10.1. Predominantly aerobic wastewater treatment processes are implemented and run in dairies. Their effectiveness in order to reduce the organic freight is out of discussion. Nevertheless a high amount of sludge surplus is generated by an aerobic process, causing additional costs for sludge treatment. Instead of metabolizing the organic load by aerobic processes, producing worthless carbon dioxide (CO2) and biomass, respectively, sludge, anaerobic digestion processes should be implemented. Preferable two-phase systems digest not only organically high loaded wastewater but also solid organic residues with a high water content. AD produces biogas which substitutes fossil energy sources. Electrical and thermal energy is gained by utilizing biogas with combined heat and power units (CHP). A recent review on anaerobic treatment of dairy waste waters is given by Demirel et al. (2005). All liquid and pasty effluents from milk processing are utilizable for anaerobic digestion. Nowadays separated streams of by-products are used as feedstock for various products, such as food or beverage ingredients. Whey, a by-product in cheese processing dairies, and its alternative utilizations are introduced and thoroughly described. Due to its composition whey offers the possibility to obtain an energetic surplus of electricity and thermal energy by burning biogas, gained out of anaerobic digestion. © 2007 Springer Science+Business Media, LLC.