Cheese Whey Treatment Using a Microbial Electrolysis Cell-Assisted Anaerobic Digestion System: The Effects of Pretreatment, Organic Loading and Applied Potential

Abstract This study deals with the feasibility of Cheese Whey (CW) treatment using a Microbial Electrolysis Cell-Anaerobic Digestion (MEC-AD) system. For this purpose, two identical reactors were constructed, a control (AD) and a MEC-AD reactor. The MEC-AD operated for 310 d and the effects of (a) CW pretreatment, (b) Organic Loading Rate (from 1.4 to 3.3 g COD /(L d)) and (c) applied potential (1 and 2 V) were examined on the MEC-AD performance. The results showed that the AD reactor failed to treat CW in every case examined, whereas the MEC-AD successfully treated the CW. In particular, the optimal CW treatment was obtained with the pretreated CW, at the OLR of 2.1 g COD /(L d) and at the applied potential of 1 V and achieved a COD removal of 98% and a residual COD concentration of 1.2 g COD /L. The optimal CH 4 yield was obtained with the pretreated CW, at the OLR of 3.3 g COD /(L d) and at the applied potential of 1 V and was 0.75 L CH4 /g sCODconsumed , higher than any yield obtained utilizing AD systems. Overall, the results showed that the MEC-AD system is a very promising technology for treating CW with simultaneous CH 4 production, whereas the AD process fails. Graphical Abstract