David C. Sego

Color and chlorinated organics removal from pulp mills wastewater using activated petroleum coke

Delayed petroleum coke, a waste by-product from the oil sand industry, was utilized in the production of activated carbon. The activated carbon was then evaluated for color and chlorinated organics reduction from pulp mill wastewater. The activation of the petroleum coke was evaluated using a fixed bed reactor involving carbonization and activation steps at temperature of 850 degrees C and using steam as the activation medium. The activation results showed that the maximum surface area of the activated coke was achieved at an activation period of 4 h. The maximum surface area occurred at burnoff and water efficiency of 48.5 and 54.3%, respectively. Increasing the activation period to 6 h resulted in a decrease in the surface area. Methylene blue adsorption results indicated that the activation process was successful. Methylene blue adsorbed per 100 g of applied activated coke was 10 times higher than that adsorbed by raw petroleum coke. Adsorption equilibrium results of the bleached wastewater and the activated coke showed that significant color, COD, DOC and AOX removal (> 90%) was achieved when the activated coke dose exceeded 15,000 mg/L. Adsorption isotherms, in terms of COD, DOC, UV and color were developed based on the batch equilibrium data. Based on these isotherms, the amount of activated coke required to achieve certain removal of color and AOX can be predicted. The utilization of the petroleum coke for the production of activated carbon can provide an excellent disposal option for the oil sand industry at the same time would provide a cheap and valuable activated carbon.

Predicting the axial capacity of screw piles installed in western Canadian soils

The results of 26 full-scale static axial load tests are presented for screw piles installed in Alberta and British Columbia since 1998, and the effectiveness of three design methods are evaluated for predicting the axial capacity of screw piles in cohesive and cohensionless soils. Theoretical formulations for capacity calculations are examined alongside the LCPC direct pile design method, and an empirical relationship correlating the installation torque to the ultimate screw pile capacity. RESUME Les resultats de 26 essais de chargement statiques sont presentes pour des pieux visses installes en Alberta et en Colombie Britannique depuis 1998 ainsi que l’evaluation de trois methodes de conception utilisees pour predire la capacite axiale des pieux visses en sols pulverulents. Les formules theoriques utilisees pour fins de calcul de la capacite sont examinees en parallele avec la methode du LCPC et une relation empirique etablissant la correlation avec la capacite ultime d’un pieu visse.

The use of a convective heat flow model in road designs for Northern regions

Roads and highways in northern environments are exposed to harsh climatic conditions. In particular, changes in temperature of several tens of degrees centigrade between the seasons, and substantial precipitation as well as permafrost conditions are common. These environmental conditions result in significant damages to the infrastructure that requires extensive maintenance. Road damage is directly related to problems associated with the foundation, frequently resulting in differential settlements. Significant increase in these problems is expected as a result of changing climate, thus reducing the expected service life of various roads in arctic regions. The highway system within the permafrost region is extremely vulnerable to these climate changes because the mechanical property of the soil changes dramatically with temperature increases and as ice within the frozen soil thaws. This paper presents a numerical investigation of a novel approach for an improvement of road foundations resulting from convective heat flow. The proposed foundation is capable of compensating for some of the expected warming of the permafrost by storing and maintaining the cold winter temperatures through the summer months. The numerical model demonstrated the importance of considering convective heat flows to optimize the design of the foundation with a focus on minimizing the effect of climate warming.

Trickle-freeze separation of contaminants from saline waste water

This study investigated the feasibility of using trickle-freeze separation as an alternative method of reducing the salinity of oil sands process water. Using a specially designed flume housed in a cold room, an experiment was conducted to determine the degree of separation and subsequent concentration of salts during freezing and melting of saline water. During the freeze – thaw cycle, the majority of salts were concentrated into less than one quarter of the original frozen volume. Utilizing results from the laboratory-scale experiments, a trickle-freeze separation system was designed to treat 20 million m3/year of saline process water. The capital investment for construction of the system was Can

CONSTRUCTION OF TWO LARGE-SCALE WASTE ROCK PILES IN A CONTINUOUS PERMAFROST REGION

127 million or Can

Snow Characterization at a City Snow Storage Facility

6.36/m3 capacity, slightly higher than for a conventional desalination processes. Annual operating costs of Can

Diavik waste rock project : thermal transport in a covered waste rock test pile

0.13/m3 of waste water are significantly lower than for conventional desalination. The design and cost estimate provided insight into the feasibility of using trickle-freeze separation as a treatment option for oil sands process water.

Waste Rock Biogeochemistry in a Permafrost Environment: Examination of a Cover Design for a Low-Sulfide, Granitic Waste Rock

The discovery of diamonds in Canada’s North has led to renewed interest in the development of mining properties in the Arctic. At the Diavik Diamond Mine Inc. operation, open pit mining will lead to the construction of two 200 Mt permanent stockpiles of waste rock. A rigorous, quantitative framework for assessing the long-term environmental implications of storing waste rock in regions with continuous permafrost has yet to be developed. Our study involves the construction of two large-scale waste rock piles (15 m in height × 60 m × 50 m) to assess the evolution of the hydrology, geochemistry, temperature, and biogeochemistry of the waste rock piles over time. One test pile will contain rock with a sulfide content of < 0.04 wt% S and the other test pile contains rock with > 0.8 wt% S. Complementary studies involving conventional static and kinetic tests on small test samples have also been initiated. The results from this five-year study will assist mining companies and regulators in evaluating current waste rock pile designs. This paper describes the construction of test piles, preliminary modeling of heat transfer and oxygen transport within the piles, and additional testing planned to quantify the relationship between weathering rates in laboratory dissolution tests and those in waste rock piles in the field. Additional

Groundwater Geochemical Characterization of a Fuel-Contaminated Fractured Bedrock in a Permafrost Environment

A field investigation involving snow coring, surveying, and melt water collection was undertaken at a city snow storage facility to characterize the snow and melt water in Edmonton, Alberta, Canada. The investigation revealed a high content of both salts and sediment within the snow, a pile volume of 500,000  m3 , a snow density of 0.63–0.83 g/ cm3 , and an average road salt content of 1.2 g/L within the melted snow. The salt within the Poundmaker snow pile, one of Edmonton’s five snow storage sites, represented approximately 1.5–2.0% of the total amount of salt that was used on the city roads during the 2006/2007 winter. Melt water fractionation took place on-site during the spring melt and salt concentrations in the March melt water (early spring) were often more than 10 times the concentration of the bulk snow. Some of the factors affecting the snow and melt water composition included the snow retention time on streets, snow source, weather/climate, sampling technique, and snow site characteristics/ope...

Diavik waste rock project : characterization of particle size, sulfur content and acid generating potential

Covers are widely used in the management of mine tailings and waste rock and most current cover design s and constructions are in temperate regions. However in cold regions, certain features and processes are un ique and they can be utilized to reduce the production of ac id rock drainage (ARD). An field study of the therm al behaviour of an experimental covered waste rock pil e in a continuous permafrost region is presented. T he results indicate that a till unit within the cover remains at sub zero temperatures. The study found that the mean annual heat flux at the base of the layer was signi ficantly less than at the surface due heat retentio n in the cover and soil saturation levels. The ratio of net radiat ion to surface heat flux is high and this is common for bare soil surfaces.