“…CW is composed by lactose (44-52 g.L -1 ), proteins (6-10 g.L -1 , primarily β-lactoglobulin) and lipids (4-5 g.L -1 ) 13,14 , has a high COD (50-102 gO 2 .L -1 ), and contains some hardly biodegradable proteins which require CW to be treated before being discharged 11 . Several studies about CW treatment were reported 11,15 , including its valorization through the production of: H2 20,23,25 , micronutrient fertilizers 15 , VFAs 5,19,27,29,31 or biogas production using immobilized cells 16 . Regarding this last, cell immobilization has several advantages as compared to suspended cultures since: (i)-it prevents microbes washout in continuous process by separating dilution rate and hydraulic retention time (HRT), (ii)-it allows to work at higher cell density, (iii)-it confers an advantage for the microbial consortium against adverse conditions 13 , and (iv)-it helps downstream processes as cells are retained within the support material and separated from the liquid.…”