Publications by authors named "Steve Helle"

Fruit and vegetable waste (FVW) was co-digested with first stage (FSS) and second stage anaerobic digester sludge (SSS) separately, over the course of 10 days, in batch reactors. Addition of FVW significantly increased the methane production in both sludges. After 10 days of digestion FSS + FVW produced 514 ± 57 L CH(4) kg VS(-1)(added) compared with 392 ± 16 L CH(4) for the SSS + FVW.

View Article and Find Full Text PDF

Fly ash (FA) and bottom ash (BA) from a softwood pellet boiler were characterized and evaluated as soil amendments. In a greenhouse study, two plant species (rye grass, Lolium perenne L. and oats, Avena sativa) were grown in three different treatments (1% FA, 1% BA, non-amended control) of a silty loam soil.

View Article and Find Full Text PDF

Anaerobic digestion is a well established technology for the reduction of organic matter and stabilization of wastewater. Biogas, a mixture of methane and carbon dioxide, is produced as a useful by-product of the process. Current solid waste management at the city of Prince George is focused on disposal of waste and not on energy recovery.

View Article and Find Full Text PDF

Recovered fibre from pulp mills represents a potentially significant feedstock for conversion to ethanol. Enzymatic hydrolysis of untreated recovered fibre (86.5 Kappa, 13% lignin) resulted in a hexose yield of approximately 23%, which highlighted the need for an effective pretreatment.

View Article and Find Full Text PDF

Fermentable sugar obtained from lignocellulosic material exhibits great potential as a renewable feedstock for the production of bio-ethanol. One potentially viable source of fermentable sugars is pyrolysis oil, commonly called bio-oil. Depending on the type of lignocellulosic material and the operating conditions used for pyrolysis, bio-oil can contain upwards of 10 wt% of 1,6-anhydro-beta-D-glucopyranose (levoglucosan, LG), an anhydrosugar that can be hydrolyzed to glucose.

View Article and Find Full Text PDF

Anhydro sugars, produced during wood pyrolysis, can by hydrolyzed to sugars under acidic conditions. The acid hydrolysis of two common anhydro sugars in wood pyrolysis oils, levoglucosan (1,6-anhydro-beta-D-glucopyranose) and cellobiosan (beta-D-glucopyranosyl-(1-->4)-1,6-anhydro-D-glucopyranose), was investigated. Levoglucosan hydrolysis to glucose follows a first-order reaction, with an activation energy of 114 kJ mol(-1).

View Article and Find Full Text PDF

Spent sulfite pulping liquor (SSL) is a high-organic content byproduct of acid bisulfite pulp manufacture which is fermented to make industrial ethanol. SSL is typically concentrated to 240 g/l (22% w/w) total solids prior to fermentation, and contains up to 24 g/l xylose and 30 g/l hexose sugars, depending upon the wood species used. The xylose present in SSL is difficult to ferment using natural xylose-fermenting yeast strains due to the presence of inhibitory compounds, such as organic acids.

View Article and Find Full Text PDF