Efficiency of sweet whey fermentation with psychrophilic methanogens

Sweet whey is a waste product from the dairy industry that is difficult to manage. High hopes are fostered regarding its neutralization in the methane fermentation. An economically viable alternative to a typical mesophilic fermentation seems to be the process involving psychrophilic bacteria isolated from the natural environment. This study aimed to determine the feasibility of exploiting psychrophilic microorganisms in methane fermentation of sweet whey. The experiments were carried out under dynamic conditions using Bio Flo 310 type flow-through anaerobic bioreactors. The temperature inside the reactors was 10 ± 1 °C. The HRT was 20 days and the OLR was 0.2 g COD/dm(3)/day. The study yielded 132.7 ± 13.8 mL biogas/g(CODremoved). The CH(4) concentration in the biogas was 32.7 ± 1.6%, that of H(2) was 8.7 ± 4.7%, whereas that of CO(2) reached 58.42 ± 2.47%. Other gases were also determined, though in lower concentrations. The COD and BOD(5) removal efficiency reached 21.4 ± 0.6% and 17.6 ± 1.0%, respectively.