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The effects of surfactants addition on enzymatic hydrolysis and subsequent fermentation of steam exploded lodgepole pine (SELP) and ethanol pretreated lodgepole pine (EPLP) were investigated in this study. Supplementing Tween 80 during cellulase hydrolysis of SELP resulted in a 32% increase in the cellulose-to-glucose yield. However, little improvement was obtained from hydrolyzing EPLP in the presence of the same amount of surfactant. The positive effect of surfactants on SELP hydrolysis led to an increase in final ethanol yield after the fermentation. It was found that the addition of surfactant led to a substantial increase in the amount of free enzymes in the 48 h hydrolysates derived from both substrates. The effect of surfactant addition on final ethanol yield of simultaneous saccharification and fermentation (SSF) was also investigated by using SELP in the presence of additional furfural and hydroxymethylfurfural (HMF). The results showed that the surfactants slightly increased the conversion rates of furfural and HMF during SSF process by Saccharomyces cerevisiae. The presence of furfural and HMF at the experimental concentrations did not affect the final ethanol concentration either. The strategy of applying surfactants in cellulase recycling to reduce enzyme cost is presented.

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Investigations were undertaken on a full scale lagoon treatment system receiving effluents from a bleached kraft pulp and paper mill which processed softwoods. The system was examined over four phases, including lagoons, aerobic transport channels and the recipient discharge point to determine the removal efficiency of resin acids during effluent treatment. The total treatment system removed 96% of the influent resin acids. The major compounds remaining after treatment were abietic acid, dehydroabietic acid, and a variety of hydrogenated resin acid transformation products. Each section of the treatment system differed in its ability to remove the major classes of resin acids. For example, the average removal rates for resin acids within the first phase lagoons and of the channel leaving the lagoons were 1.2 and 17 g.kg-1 VSS.day-1, respectively. A pathway for the biodegradation and biotransformation of influent resin acids is proposed on the basis of the observed changes in effluent composition through the treatment system.