Robert Lagacé

Comparison of the gaseous and particulate matter emissions from the combustion of agricultural and forest biomasses.

The aim of this study was to compare gaseous and particulate matter (PM) emissions from the combustion of agricultural (switchgrass, fast-growing willow and the dried solid fraction of pig manure) and forest (wood mixture of Black Spruce and Jack Pine) biomasses in a small-scale unit (17.58kW). Concentrations of CO2, CO, CH4, NO2, NH3, N2O, SO2, HCl, and H2O were measured by Fourier transform infrared spectroscopy and converted into emission rates. Opacity was also evaluated and particulates were sampled. Results showed significantly higher emissions of SO2, NO2 and PM with the combustion of agricultural biomass compared to the forest biomass. However, further studies should be carried out so regulations can be adapted in order to permit the combustion of agricultural biomass in small-scale combustion units.

Modeling Sediment Movement into Perforated Subsurface Drains

ABSTRACT IN order to predict the amount of sediment in subsur-face drain pipes, an analogy was established between the drain cross sectional area occupied by sediment and the amount of granular material that flowed in a confined volume through a perforation before a bridge formed. Experiments were performed using glass beads and eight different types of sand using a permeameter-like apparatus. Various parameters related to the shape and dimension of the perforations and to the particle size distribution of the sands were investigated. Results indicate that a sigmoid model describes more accurately than a linear model the relationships between the amount of material and the various factors related to the geometry of the perforation. For the eight sand types, the amount of material is best predicted (R2 = 0.828) from the hydraulic radius of the perforation and from the D60 of the sand.

Thin-section study of soil materials near perforations in corrugated subsurface drains

Abstract Laboratory experiments with drainage simulators were performed using a sample of weakly structured sandy loam and four different types of corrugated subsurface drains. Following the experiments, thin sections were made to investigate the soil arrangement near drain perforations. Results show that soil aggregates can form bridges that will stop the flow of sediment into the drain. Bridges formed of individual soil particles were observed at drain openings. For the weakly structured sandy loam studied, the soil material near the drain is not homogeneous. Preferential channels leading to drain openings were observed near 16 of 38 perforations.

Verification of a Model Predicting Sediment Level in Subsurface Drains

ABSTRACT AN arctangent sigmoid model to predict sediment level in perforated subsurface drains is compared to results from five different sets of data found in the literature. The experiments reported in the literature ranged from the study of bridging with dry sand to a field investigation using corrugated plastic drains. Most of the data analyzed with the arctangent sigmoid model yielded an R2 greater than 0.90 when each soil was considered individually. For experiments with dry sands in a permeameter, the grouping of the sediment level from different soils was made possible by the use of the D60 only (R2 > 0.99). For sands in a permeameter with downward flow, the use of both the D60 and the coefficient of uniformity (CU) was necessary in order to obtain results with a high correlation (R^ = 0.918). For a field experiment, an R^ of 0.844 was reached using the D60, D85 and CU.