EFFECTS OF PETROLEUM HYDROCARBON CONCENTRATION AND BULK DENSITY ON THE HYDRAULIC PROPERTIES OF LEAN OIL SAND OVERBURDEN AND WATER STORAGE IN OVERLYING SOILS

Coarse textured soils with low water and nutrient retention are commonly the only available materials for reclamation of the projected 480,000 hectares of disturbed land in the Alberta oil sands. It is important to understand the processes in the soils being used for reclamation to be able to re-create conditions that occurred prior to disturbance. Extensive research has been conducted to understand the hydraulic processes in mineral soils, however much of the soils that are used for reclamation in the Alberta oil sands are impregnated with petroleum hydrocarbons (PHCs). Little is known of the effects of PHCs on soil hydraulic properties. Lean oil sand (LOS) is an overburden material that contains PHCs, and is considered mine waste. LOS must be reclaimed, and is currently being tested as the base soil layer for some of the reclamation being conducted in the Alberta oil sands. It is important to understand how the hydraulic properties in the LOS as well as in the overlying reclamation soils will be affected by PHCs. The main objective of this thesis is to determine the efficacy of using LOS as a base soil layer on the successful reclamation of disturbed land in the Alberta oil sands. This was done by: 1) Evaluating how PHCs and bulk density influence the hydraulic properties of LOS and 2) Determining how the soil hydraulic properties in the layers overlying the LOS are affected by the heterogeneity of PHC concentration and bulk density of the LOS. Soil cores were packed with LOS with varying PHC concentrations and bulk densities to test water retention curves and saturated hydraulic conductivity of the LOS. Soil columns were packed with a base LOS layer and reclamation cover soils that are used in the Alberta oil sands. The soil columns were used to test water and nutrient dynamics in the reclamation soil profile. It was found that both bulk density and PHC concentration had an effect on the hydraulic properties in LOS as well as in the overlying reclamation profile. The porosity of soil is largely affected by bulk density, so as bulk density of the LOS increased, it lead to lower water retention at saturation, but higher water retention at soil suctions associated with field capacity and permanent wilting point (PWP). This led to LOS at higher bulk densities having higher available water holding capacity (AWHC) and lower Ks, providing the overlying soil profile with more water and nutrients for a longer time for plants to access. Furthermore, PHCs reduced water retention in LOS due to plugging mainly the soil micropores pores and connecting porosity. This lead to lower Ks of the LOS, which resulted in an increased water and nutrient retention in the overlying soil profile. Results show that the use of LOS in the reclamation of coarse textured soils in the Alberta oil sands can aid in creating suitable soil conditions leading to reclamation success

Nanofiltration for the Treatment of Oil Sands-Produced Water

This chapter summarizes nanofiltration (NF) studies focused on the treatment of thermal in-situ steam-assisted gravity drainage (SAGD)-produced water streams in the Alberta, Canada, oil sands industry. SAGD processes use recycled produced water to generate steam, which is injected into oil-bearing formations to enhance oil recovery. NF has potential applications in the produced water recycling treatment process for water softening, dissolved organic matter removal, and partial desalination, to improve recycle rates, reduce make-up water consumption, and provide an alternative to desalination technologies (thermal evaporation and reverse osmosis). The aim of this study was to provide proof-of-concept for NF treatment of the following produced water streams in the SAGD operation: warm lime softener (WLS) inlet water, boiler feed water (BFW), and boiler blowdown (BBD) water. Commercial NF membranes enabled removal of up to 98% of the total dissolved solids (TDS), total organic carbon (TOC), and dissolved silica, which is significant compared to the removal achieved using conventional SAGD-produced water treatment processes. More than 99% removal of divalent ions was achieved using tight NF membranes, highlighting the potential of NF softening for oil sands-produced water streams. The NF process configurations studied provide feasible process arrangements suitable for integration into existing and future oil sands and other produced water treatment schemes

Microflotation performance for algal separation

This is the peer reviewed version of the following article: HANOTU, J., BANDULASENA, H.C.H. and ZIMMERMAN, W.B., 2012. Microflotation performance for algal separation. Biotechnology and Bioengineering, 109 (7), pp. 1663-1673, which has been published in final form at http://dx.doi.org/10.1002/bit.24449. This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving'.The performance of microflotation, dispersed air flotation with microbubble clouds with bubble size about 50 µm, for algae separation using fluidic oscillation for microbubble generation is investigated. This fluidic oscillator converts continuous air supply into oscillatory flow with a regular frequency to generate bubbles of the scale of the exit pore. Bubble characterization results showed that average bubble size generated under oscillatory air flow state was 86 µm, approximately twice the size of the diffuser pore size of 38 µm. In contrast, continuous air flow at the same rate through the same diffusers yielded an average bubble size of 1,059 µm, 28 times larger than the pore size. Following microbubble generation, the separation of algal cells under fluidic oscillator generated microbubbles was investigated by varying metallic coagulant types, concentration and pH. Best performances were recorded at the highest coagulant dose (150 mg/L) applied under acidic conditions (pH 5). Amongst the three metallic coagulants studied, ferric chloride yielded the overall best result of 99.2% under the optimum conditions followed closely by ferric sulfate (98.1%) and aluminum sulfate with 95.2%. This compares well with conventional dissolved air flotation (DAF) benchmarks, but has a highly turbulent flow, whereas microflotation is laminar with several orders of magnitude lower energy density. Biotechnol. Bioeng. 2012; 109:1663–1673. © 2012 Wiley Periodicals, Inc

Drinking water coagulation with polyaluminum coagulants: Mechanisms and selection guidelines

In recent years, polyaluminum coagulants have received considerable interest as drinking water coagulants. Many types of polyaluminum coagulants are commercially available, including polyaluminum chloride (PACl), aluminum chlorohydrate, and polyaluminum sulfate (PAS). Unlike alum, these products differ in their basicity and strength, and can contain varying amounts of other substances, such as sulfate, silica, and calcium. The chemistry of polyaluminum coagulants is not well known, coagulation mechanisms have not been studied as extensively, and comprehensive guidelines on the selection and use of these different polyaluminum coagulants currently do not exist. In this research, several polyaluminum coagulants were examined for five different raw water types and three solid-liquid separation processes. Coagulants of different chemistry were evaluated: alum, PACl, PAS, and aluminum chlorohydrate. PACls of low, medium, and high basicities, with or without sulfate were examined. The solubility and Al speciation of the coagulants were investigated. As well, treatment experiments were performed with five widely different water supplies with sedimentation, dissolved air flotation (DAF) and direct filtration. The performance of the coagulants was evaluated for turbidity and NOM removal. Guidelines were developed for choosing polyaluminum coagulants and selecting doses based on water quality parameters, coagulant characteristics, and treatment process. The results of this research indicate that significant differences exist between the solubility of the PACls, PAS, aluminum chlorohydrate, and alum. Aluminum chlorohydrate had the highest solubility and the highest pH of minimum solubility, followed by the PACls, PAS, and alum. For the PACls, the pH of minimum solubility tended to increase with increasing basicity. The Al speciation data indicated that high basicity PACls contain the largest fraction of dissolved polymeric species in solution over the broadest pH range. The polymeric fraction present, or the pH range over which polymer was present, decreased as basicity was decreased. The selection of the appropriate coagulant for a given water treatment application was found to depend on the chemical characteristics of the coagulant, the characteristics of the raw water, and the treatment process used. High basicity PACls were found to be effective for all model waters under a wide variety of treatment conditions. PACls with added sulfate or silica were found to be especially effective for sedimentation applications. The presence of sulfate was detrimental for treatment by direct filtration. All of the PACls were effective for DAF treatment applications, although raw water alkalinity did have some influence on coagulant selection

Removal of Organoselenium from Aqueous Solution by Nanoscale Zerovalent Iron Supported on Granular Activated Carbon

Nanoscale zerovalent iron particles (nZVI) immobilized on coconut shell-based granular activated carbon (GAC) were studied to remove organoselenium from wastewater. A chemical reduction technique that involves the application of sodium borohydride was adopted for the adsorbent preparation. The texture, morphology and chemical composition of the synthesized adsorbents were analyzed with a scanning electron microscope (SEM), nitrogen adsorption–desorption isotherms and X-ray diffraction (XRD). Batch experiment with various pHs and contact times were conducted to evaluate nZVI/GAC adsorption performance. The results showed that nZVI/GAC has a strong affinity to adsorb selenomethionine (SeMet) and selenocysteine (SeCys) from wastewaters. The maximum removal efficiency for the composite (nZVI/GAC) was 99.9% for SeCys and 78.2% for SeMet removal, which was significantly higher than that of nZVI (SeCy, 59.2%; SeMet, 10.8%). The adsorption kinetics were studied by pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models. Amongst the two, PSO seemed to have a better fit (SeCy, R2 > 0.998; SeMet, R2 > 0.999). The adsorption process was investigated using Langmuir and Freundlich isotherm models. Electrostatic attraction played a significant role in the removal of organoselenium by nZVI/GAC adsorption. Overall, the results indicated that GAC-supported nZVI can be considered a promising and efficient technology for removing organoselenium from wastewater

Internal Treatment of Process Waters in Paper Production by Dissolved Air Flotation with Newly Developed Chemicals. 2. Field Trials

New chemicals, based on the synergistic effect between inorganic polyaluminium salts and organic cationic polyelectrolytes, have been tested previously at laboratory-scale, and the most efficient product has been selected for an industrial trial for a dissolved air flotation unit of a paper mill based on 100% recovered paper (part 1 of this work). A polyaluminium nitrate sulfate salt combined with a quaternary polyamine has been evaluated in a long-term industrial trial for assessing its potential benefits. Results indicate that this new chemical is able to improve the removal of contaminants by dissolved air flotation, especially when the contamination load of the waters is high, allowing a further closure of the water circuits