Efficient dewatering of oil sands tailings is imperative to reduce the environmental footprint of oil sands operators. Currently there is no mature technology capable of effectively treating oil sands tailings and completely eliminating the use of tailings ponds. Consolidated tailings and paste technology are the most extensively used dewatering methods. However, the high concentrations of divalent ions in the water recovered using the consolidated tailings process impedes the re-utilization of this water in the bitumen extraction process. Accumulation of ions does not occur in the case of paste technology; however, this technology, similarly to the consolidated tailings process, recovers only part of the water from tailings and produces high-water content sediments (25-30 wt. % solids) that sill requires special storage. This happens because the sediments produced by polyacrylamide (PAM) flocculants are not closely packed and require the application of other consolidation technologies (e.g., freeze-thaw, filtration, centrifugation) to obtain dry and self-supportive tailings. This review focuses on examining alternative flocculants that could potentially replace PAM polymers in mature and new dewatering technologies. Flocculants are a key element of many tailing treatments including paste technology and filtration. The "ideal" flocculant would increase the ability of these technologies to dewater tailings, resulting in higher water recovery and sediment consolidation without affecting water chemistry or increasing operational costs. This review presents a comparison between PAM flocculants and two promising alternative flocculants: inorganic-organic hybrid and temperature-sensitive polymers. Each flocculant type is evaluated in terms of its flocculation mechanisms and its dewatering efficacy.

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This work reports the synthesis of particles based on poly(3-hydroxybutirate-co-3-hydroxyvalerate) (PHBV) polymer that were impregnated with progesterone. The PHBV particles were obtained by supercritical CO 2 (scCO 2 ) anti-solvent expansion (SAS). scCO 2 was also used at a high pressure (25 MPa) and moderate temperature (323 K) for the impregnation of progesterone into the PHBV particles at different impregnation times. In vitro release tests showed that the half-time of progesterone release in a hydro-alcoholic medium, for the samples produced with impregnation times of 2-32 h, was 3-5 h, with the higher release times generally related to smaller impregnation times.

This work reports new experimental data for the oxidation degradation of landfill leachate using supercritical water treatment (ScWO) without addition of any oxidants. The treatment reduced significantly the original concentration of pollutant compounds in the liquid waste. The parameters used to evaluate the efficiency of the treatment (and leachate degradation) were chemical oxygen demand (COD), total organic carbon (TOC), turbidity, colour, and absorbance. The experiments were conducted using a continuous flow reactor built in Inconel 625. The degradation oxidation reactions were carried out using temperature between 350 and 600 °C (for COD intial concentrations of 1580 mg · L−1) and between 450 and 700 °C (for COD intial concentrations of 2000 mg · L−1), pressures of 15 and 22.5 MPa, feed streams of 6 and 12 g · min−1, and reaction operation time of 40 min. Increasing pressure improved degradation of organic pollutant compounds, whereas the increase of the feed flow rate did not show any positive effect on the performance of the treatment. However, the most important factor on the degradation of leachate was temperature; increasing temperature from 350 to 600 °C reduced COD level in 31.3 and 34.4 % for 15 and 22.5 MPa, respectively. Hydrogen was the gas produced in the highest amount for all the experimental conditions studied. The results suggested that supercritical water is a promising technique to treat leachate and consequently reduce its pollutant capacity. Thus, the data presented here can be used as a basis for future studies.

This study reports the oil extraction efficiency using Moringa oleifera seed and pressurized propane, new experimental data for phase transition of the binary system {n-propane þ Moringa oleifera oil}, and the profile of fatty acid compositions of the extracted Moringa oil. During the present study, the knowledge of the phase behaviour proved to be of great importance to optimize supercritical extraction using pressurized fluid. This project also compares the classical Soxhlet method including mathematical modelling of kinetic curves of extraction. The extraction experiments were performed in the temperature and pressure ranges of 303-333 K and 2.5-12 MPa, respectively, at a constant flow rate of 1.0 cm 3 /min of n-propane. All the conditions applied during the n-propane extraction process provided similar or higher yields (32.8 to 42.1 %) compared to extractions using n-hexane (42.6 %) and supercritical carbon dioxide (SC-CO 2 ) (37.8 %). In addition, phase transition study for the {Propane (1) þ Moringa ole ıfera oil (2)} system was performed using a variable volume cell and the static synthetic method in a temperature range of 303-343 K, pressures up to 3.23 MPa, and n-propane mass fraction between 0.2 and 0.8. Vapour-liquid (VLE), liquid-liquid (LLE), and vapourliquid-liquid (VLLE) phase transitions were observed at relatively low pressures. The fatty acid profiles of the extracted Moringa oils were evaluated using gas chromatography. They all have very close composition regardless of the solvent used and oleic acid as the major component (%76 %). The Sovov a mathematical model indicated a good fit for all the conditions investigated.

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New data on total organic carbon (TOC) reduction and H2 production were obtained by using supercritical water oxidation of lactose with and without oxidant agents (H2O2 and t‐BHP) in a continuous Inconel 625 flow reactor. The oxidation reactions were carried out at 550 and 700 °C, 22.5 MPa, 0.025 g/g (2.5 wt%) lactose concentration, feed flow rate of 5 g · min−1, and a total reaction time of 90 min. The average production of H2 yielded 4.5 mol/mol lactose with TOC reduction of ∼99 %. The results obtained in this study with supercritical water oxidation (SCWO) may be used to generate energy via production of H2 from dairy industry effluents.

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