Novel Batch Reactor for the Dilute Acid Pretreatment of Lignocellulosic Feedstocks with Improved Heating and Cooling Kinetics

The pretreatment of lignocellulosic biomass is an important part of the process of utilizing a renewable and abundant feedstock. This paper aims to provide a novel lab-scale batch pretreatment reactor that significantly improves heating and cooling kinetics over typical batch pretreatment reactors, yet made from readily available parts. The heating and cooling kinetics of a batch pretreatment reactor are important for emulating the behavior of a large scale continuous reactor system. The heat transfer performance has been quantified and presented here as a tool for aiding the design of a similar reactor system. One important lignocellulosic feedstock is corn stover, which was used in this study to validate the reactor performance. The pretreatment method that was used in this study is the dilute acid pretreatment. The pretreatment runs were enzymatically saccharified to evaluate the pretreatment effectiveness. The results from this enzymatic saccharification were compared with several literature sources to validate the reactor performance. The pretreatment conditions that were used are 0.5 wt% sulfuric acid, 10 minute pretreatment time, and 10 wt% solids loading. The enzymatic digestibility of the cellulose in the pretreated solids was 53.3% at 150°C and 72.1% at 160°C.

Sludge pretreatment before aerobic digestion to enhance pathogen destructionA paper submitted to the Journal of Environmental Engineering and Science.

Bench scale experimentation was completed to assess the potential of using a short residence time pretreatment reactor upstream of aerobic digestion to enhance the destruction of pathogens. The impact of aeration, temperature, hydraulic residence time (HRT), solids concentration, and feeding frequency on the pretreatment process was investigated. Subsequent testing evaluated pathogen destruction resulting from the operation of selected pretreatment conditions in a staged configuration with conventional aerobic digesters. Either highly oxidative or highly reductive conditions were observed to be most effective in reducing the concentrations of E. coli. and Salmonella spp. in the pretreatment reactor. When operated in series with the aerobic digesters, the more highly reducing conditions in pretreatment were found to enhance die-off of the microorganisms in subsequent aerobic digestion compared to the control.