Augmentation of secondary organics for enhanced pretreatment of thermomechanical pulping wastewater in biological acidogenesis

Thermomechanical pulping (TMP) wastewater was used for augmenting readily biodegradable organics in order to enhance microbial hydrolysis by mesophilic and thermophilic acidogens. A biochemical methane potential test with the TMP wastewater revealed that approximately 12-14% of the total chemical oxygen demand was anaerobically biodegradable. Mesophilic and thermophilic acidogens at 35 and 55 degreesC in batch mode were tested to investigate the effects of various concentrations of organic acids and ethanol produced from readily biodegradable organics on the hydrolysis of lignocellulosics. The experiment was designed to have initial glucose concentrations of 5, 15 and 30 g/l. The combined effects of the production of organic acids, ethanol, and enriched acidogenic populations by addition of glucose promoted hydrolysis. Compared to the control with no glucose addition, approximately 5.3 and 6.6 times more fragmentation of lignocellulosics in the wastewater occurred in mesophilic and thermophilic acidogenesis, respectively. Higher efficiencies in the thermophilic trials than those in the mesophilic tests were likely due to the elevated temperature. (C) 2003 Elsevier Science Ltd. All rights reserved.