EXPLORING OPTIMAL FEED TO MICROBES RATIO FOR ANAEROBIC ACIDOGENIC FERMENTATION OF CASSAVA RESIDUE FROM BREWERY

• Main Authors: Xinying Wang, Shuting Zhang, Jing Wang, Xiaoyan Yu, Xuebin Lu
• Format: Article
• Language: English
• Published: North Carolina State University 2012-01-01
• Series: BioResources
• Subjects: Cassava residue; Anaerobic fermentation; F/M ratio; Two stage
• Online Access: http://ojs.cnr.ncsu.edu/index.php/BioRes/article/view/BioRes_07_1_1111_Wang_ZWYL_Feed_Microbes_Ratio_Brewery_Residue_Fermentation/1385

Cassava residue from breweries is being generated in large amounts in Guangxi Province of China, and this has potential to cause serious environmental problems if disposed of improperly. Two-stage anaerobic fermentation is a promising method for the treatment of such residue. In this study, the effect of feed to microbes ratio (F/M ratio) on the anaerobic acidogenic fermentation of cassava residue was studied to determine the optimal F/M ratio and to maximize the performance in a subsequent methanogenic stage. The experiments were carried out at the F/M ratios of 0.2, 0.61, 1.02, 2.05, 3.07, and 4.09 g cassava-TS/g sludge-VSS in six laboratory-scale, completely stirred, tank reactors (CSTR) at mesophilic temperature (35°C). An F/M ratio of 1.02 g cassava-TS/g sludge-VSS resulted in the highest solid removal efficiency and VFA/COD ratio, while starch removal efficiency was still near 100 percent, and acidification was relatively high. As a further benefit, the VFA distribution was more suitable for the subsequent methanogenic fermentation stage.