Hydrogen and methane two-stage production directly from brewery effluent by anaerobic fermentation

Methane fermentation using an upflow anaerobic sludge blanket (UASB) process is extensively applied to the treatment of brewery effluents. However, the UASB process is not suited to efficiently process solid-containing effluents. Therefore, the feed solution requires a pretreatment to remove any suspended solid matter. For example, the pressed filtrate from the spent malt of the lauter tun contains a high density of suspended matter (chemical oxygen demand [COD], 30,000-60,000 mg/L). Physical removal of the suspended matter from this filtrate lowers the soluble COD concentration (10,000-30,000 mg/L). If it is possible to convert the suspended matter into biogas, more than twice the volume of biogas would be obtained from the waste of the lautering process. Some bacteria found from the anaerobic fermentation decompose high-molecular-weight polysaccharides into low-molecular-weight sugars and organic acids, generating hydrogen as a metabolite. In this paper, a bench-scale empirical study of hydrogen and methane two-stage production directly from brewery effluent, containing a high level of solid matter content, was carried out, resulting in about a 7% increase in the energy balance in terms of kilojoules per liter of supplied liquid due to the solubilization of the suspended solids occurred.