Fermentation of cheese whey powder solution to ethanol in a packed‐column bioreactor: effects of feed sugar concentration

A review on fermentative hydrogen production from dairy industry wastewater

“…The organic content of dairy wastewaters is typically in the range of 1 to 10 g COD L −1 and 0.3 to 5.9 g BOD 5 L −1 while seasonal variations are correlated with the volume of milk received for processing . Whey wastewater is a by‐product of the cheese‐making process with a high content of lactose, soluble proteins, lipids and mineral salts along with COD concentrations up to 80 g L −1 and it is an ideal source for bioenergy production with its high biodegradability . Low concentrations of some heavy metals also have been reported in dairy wastewater …”

Performance of different immobilized‐cell systems to efficiently produce ethanol from whey: fluidized batch, packed‐bed and fluidized continuous bioreactors

“…Cell‐immobilized bioreactors have contributed to bioprocesses optimization due to their unique characteristics of high volumetric productivity, small operational volumes, cell protection against inhibitory products, and shorter reaction times when compared with free‐cell bioreactors 1, 2. Ethanol production in cell‐immobilized bioreactors has been studied using different entrapment supports, such as cellulose beads,3 agar,4 delignified cellulosic materials,5 alginate,6–8 sorghum bagasse,9 and olive pits,10 among others. However, alginate gels are the most widely used because they are non‐toxic, inexpensive, and easy to prepare 2, 11, 12…”

“…Continuous fermentation in a packed bed bioreactor with Ca‐alginate immobilized cells has been reported with various degrees of success, and, at present, it still lacks commercial viability 8. On the other hand, some agroindustrial residues have also been studied as support for cell immobilization for the production of ethanol, among them sorgum bagasse, in a continuous packed bed column reactors operating at different dilution rates,9 and olive pits as supporting particles for cell attachment operated at different hydraulic residence time and sugar concentrations 10, 14. However, these bioreactors configurations where cells are not entrapped often release cells to the medium, losing productivity.…”

The modeling of ethanol production by Kluyveromyces marxianus using whey as substrate in continuous A-Stat bioreactors

“…Ethanol can be obtained by fermentation of different raw materials, such as agro-industrial residues, and using several microorganisms [7,14,21,32,53]. Whey, which is a by-product (sometimes a waste material) of dairy industries, is an abundant and inexpensive substrate, rich in nutrients, which could be used for ethanol fermentation because of its unique composition: high lactose content (45-50 g L −1 ), protein (6-8 g L −1 ), lipids (4-5 g L −1 ), and mineral salts (5-7 g L −1 ) [14,17,23,38,46]. Different technologies have been studied to improve the ethanol fermentation process.…”

“…Several approaches for ethanol production in continuous cell-immobilized bioreactors have been investigated using different support materials and substrates [25,27,33,35,49,54], but only recently researchers have reported the use of whey for ethanol production in immobilized continuous systems [6,13,14,38]. Considering the ever-increasing demand for ethanol production, various mathematical models have been attempted in order to predict the effect of fermentation variables on cell growth, substrate utilization rate, and ethanol production rate [4,15,43], thus allowing for better processes design.…”