Abstract not available

In this research project, systematic studies of polymer-assisted flocculation and dewatering behaviour of colloidal gibbsite (y-Al(OH)3) dispersions, together with polymeric flocculant structure-mediated interfacial chemistry and particle interactions, have been performed. Clear links between flocculation performance, interfacial chemistry, particle interactions, dispersion settling rate and sediment consolidation were established for improved dewaterability.

No description available.

Fossil fuels are not sustainable due to their worldwide depletion and greenhouse gas (GHG) emissions. Transportation biofuels produced from microalgae are sustainable if GHG emissions are lower than fossil fuels and the sources for materials used during production are sustainable. Four areas were evaluated to address these concerns. First, a study of peer reviewed life-cycle analyses (LCAs) was performed. The purpose of this evaluation was to determine which processing choices during cultivation have the most impacts. Data from nine authors was converted to similar units, and a new LCA was performed to evaluate the impacts. Overall GHG emissions per kg of algae cultivation ranged from 0.1 - 4.4 kg CO₂ eq. / kg algae, with the most of the emissions coming from fertilizer contributions. The second topic evaluated was the GHG emissions from experimental dewatering technologies. The five experimental technology emissions, for acoustic harvesting, membrane filtration, flocculation, electrocoagulation and flocculation plus belt filtration, were compared to a modeled dissolved air flotation technology and a fossil fuel source. For a functional unit of one MJ of renewable diesel (RD), membrane filtration had the lowest GHG emissions at 40.8 g CO₂(eq)/MJ RD. Dissolved air flotation was the highest scenario at 51.9 g CO₂(eq)/MJ RD. All technologies were lower than gasoline at 90.7 g CO₂(eq)/MJ gasoline. The third topic evaluated was the GHG emissions from the materials used for plant construction. A LCA was performed for the infrastructure materials and compared to results from the fuel-cycle. Plastic from pond liners had the largest contribution to GHG emissions for the baseline case. Increasing productivity and lipid content both decreased infrastructure emissions. The final topic evaluated was the sustainability of nitrogen, phosphorus and potassium used for microalgae growth. Results show that the surplus of world fertilizers cannot sustain large scale algae production in the United States. Technology choices that can recycle nutrients lower the overall requirement. Alternative sources of nutrients, like concentrated animal feeding operations, can provide enough nutrients for large scale production of algae.

No description available.

Approximately 7000 to 8000 years ago when Hudson Bay became ice-free the Tyrrell Sea flooded the Hudson basin and deposited fine grained marine sediments overlaying the previous glacial tills. Coincident with the ablation of the ice sheet isostatic rebound occurred causing regression of the Tyrell Sea and the emergence of a flat, relatively impermeable surface that would eventually host one of the world’s largest wetlands: the Hudson Bay Lowlands. The low permeability marine sediments and low regional slope reduced recharge and runoff, respectively, so that basal tidal marshes were established, and with isostatic up lift were eventually replaced by swamp forests and then forested and non-forested bogs. Recent discovery of kimberlite (diamondiferous) pipes in an area of the lowlands has led the development of an open-pit diamond mine which requires dewatering of the regional aquifer. Dewatering is depressurizing the surrounding Silurian bedrock that underlies the marine sediments. It was hypothesized that these marine sediments would act as a confining layer, isolating the overlying peatlands from the regional bedrock aquifer. We tested this hypothesis by instrumenting a 1.5 km long transect located within the zone of the mine’s influence that crossed various bogs and fens overlying these marine sediments, and was anchored at both ends by bedrock outcrops (bioherms), which represented areas of no marine sediment. Along this transect wells and piezometers were installed within the peat profile and upper marine sediments and bedrock to determine changes in water table and hydraulic head. The exposed bedrock outcrops (bioherms) did act as local drainage nodes, however, this effect was limited to ~30 m, beyond which water tables and hydraulic heads were similar to a control site located 25 km away. However, within this 30 m zone daily losses of water by the enhanced recharge often exceeded those of evapotranspiration (~3mm/day) representing a major local loss of water to the system. It is the distance to bedrock, rather than distance to bioherm, that determines strength of recharge. In areas of thinner marine sediments the daily fluxes were similar (but less) than those in the areas directly surrounding the bioherms, despite being 100s of meters away from the bioherms. The stratigraphy surrounding the bioherms lead to complicated flow regimes with higher conductivity layers (e.g., sands) circumventing the lower permeability marine sediments which may help extend the effect of the bioherms beyond the 30 m distance. The drying peat around the bioherms, and the elevated nature of the bioherms in a flat landscape, put them at increased risk for lighting strikes and thus fires; however, very little viable fuel exists in the peatlands around the bioherms and any fires that might occur would be confined to the bioherm and not spread into the surrounding peatland. Overall, at least within the first 5 years of aquifer dewatering, seasonal weather played the dominant role in affecting the hydrology of the peatlands; a heavy snow pack and cool, wet summer can mask, or at least minimize the effects of aquifer dewatering.

Approximately 7000 to 8000 years ago when Hudson Bay became ice-free the Tyrrell Sea flooded the Hudson basin and deposited fine grained marine sediments overlaying the previous glacial tills. Coincident with the ablation of the ice sheet isostatic rebound occurred causing regression of the Tyrell Sea and the emergence of a flat, relatively impermeable surface that would eventually host one of the world’s largest wetlands: the Hudson Bay Lowlands. The low permeability marine sediments and low regional slope reduced recharge and runoff, respectively, so that basal tidal marshes were established, and with isostatic up lift were eventually replaced by swamp forests and then forested and non-forested bogs. Recent discovery of kimberlite (diamondiferous) pipes in an area of the lowlands has led the development of an open-pit diamond mine which requires dewatering of the regional aquifer. Dewatering is depressurizing the surrounding Silurian bedrock that underlies the marine sediments. It was hypothesized that these marine sediments would act as a confining layer, isolating the overlying peatlands from the regional bedrock aquifer. We tested this hypothesis by instrumenting a 1.5 km long transect located within the zone of the mine’s influence that crossed various bogs and fens overlying these marine sediments, and was anchored at both ends by bedrock outcrops (bioherms), which represented areas of no marine sediment. Along this transect wells and piezometers were installed within the peat profile and upper marine sediments and bedrock to determine changes in water table and hydraulic head. The exposed bedrock outcrops (bioherms) did act as local drainage nodes, however, this effect was limited to ~30 m, beyond which water tables and hydraulic heads were similar to a control site located 25 km away. However, within this 30 m zone daily losses of water by the enhanced recharge often exceeded those of evapotranspiration (~3mm/day) representing a major local loss of water to the system. It is the distance to bedrock, rather than distance to bioherm, that determines strength of recharge. In areas of thinner marine sediments the daily fluxes were similar (but less) than those in the areas directly surrounding the bioherms, despite being 100s of meters away from the bioherms. The stratigraphy surrounding the bioherms lead to complicated flow regimes with higher conductivity layers (e.g., sands) circumventing the lower permeability marine sediments which may help extend the effect of the bioherms beyond the 30 m distance. The drying peat around the bioherms, and the elevated nature of the bioherms in a flat landscape, put them at increased risk for lighting strikes and thus fires; however, very little viable fuel exists in the peatlands around the bioherms and any fires that might occur would be confined to the bioherm and not spread into the surrounding peatland. Overall, at least within the first 5 years of aquifer dewatering, seasonal weather played the dominant role in affecting the hydrology of the peatlands; a heavy snow pack and cool, wet summer can mask, or at least minimize the effects of aquifer dewatering.

In this research project, systematic studies of polymer-assisted flocculation and dewatering behaviour of colloidal gibbsite (y-Al(OH)3) dispersions, together with polymeric flocculant structure-mediated interfacial chemistry and particle interactions, have been performed. Clear links between flocculation performance, interfacial chemistry, particle interactions, dispersion settling rate and sediment consolidation were established for improved dewaterability.

The Government of Ontario plans to ban the land application of untreated septage; however, most town wastewater treatment plants do not have the capacity to accept septage. A combined reed bed – freezing bed technology has been successfully developed to dewater and treat septage. Lab column studies established that freeze-thaw conditioning can restore drainage in clogged sand drying beds dosed with common biological sludges and that septage can be dosed at 10 cm/week for 2.5-5.0 months before clogging is observed. Pilot studies showed that freezing beds can operate without the need for a cover with the applied sludge effectively melting any snow cover in regions with moderate snowfall. Septage freezing was successfully modelled following an accepted model for ice formation on water bodies while septage thawing was modelled using a regression analysis with initial frozen depth and precipitation found to be insignificant and degree days of warming controlling the rate of thawing. Model results were utilized to produce a freezing bed design loading map for North America based on temperature normals. Field scale planted and unplanted reed bed – freezing bed systems were constructed and tested with varying hydraulic loading rates (1.9-5.9 m/y) and solid loading rates (43-144 kg/m2/y) over a 5 year period resulting in a recommended design hydraulic loading rate of 2.9 m/y or 75 kg/m2/y. Drainage rates doubled after freeze-thaw conditioning compared to during the growing season, suggesting that freeze-thaw conditioning restores filter hydraulic conductivity. No effect of solid loading rate, planted versus unplanted filters and 7 versus 21 d dosing cycles on filter drainage was observed; however, drainage varied significantly with hydraulic loading rate. The filters separated almost all contaminants with filtrate equivalent to a low-strength domestic wastewater which can be easily treated in any municipal or decentralized wastewater system. The dewatered sludge cake had similar nutrient and solid content to a solid dairy manure and met biosolid land application standards in terms of metals and pathogens. The combined reed bed-freezing bed technology can provide a low-cost solution for the treatment and reuse of septage in cold-climate regions.

In the papermaking industries spots in the finished product is a recurring problem. Billerud Korsnäs have in earlier studies identified poorly optimized retention systems as one of the reasons for these spots. Poorly optimized retention systems will allow for detrimental substances to flow freely in the system, which may cause agglomeration into larger particles that could end up as darker spots in the finished product. The aim of this thesis is to investigate a number of retention systems, consisting of a retention polymer and retention microparticles, and characterize the polymers.The retention aid systems task is to flocculate fibres, fines and fillers along with the colloidal material to improve process parameters. To investigate the retention systems three different retention polymers with different charge densities have been investigated alongside one microparticle. The parameters investigated in this thesis were the retention systems effect on drainage time, turbidity, charge demand and zeta potential. Pulp and white water from PM4 was used to imitate mill conditions.The results showed that the drainage time and turbidity was most effected by the retention aid systems. The polymer with the highest charge yielded the best results. Only minor effects could be detected on charge demand and Zeta potential.