Fulvic acid (FA) is a common refractory organic compound in landfill leachate. The degradation of FA in supercritical water oxidation (SCWO) was conducted in a SS 316 batch reactor. The effects of temperature, pressure, residence time, oxidation ratio and initial FA concentration on the degradation of FA were investigated. Results showed that FA could be easily destructed in SCWO process, and a total organic carbon (TOC) removal efficiency of 98.0% was available at 600 °C, 420 s, 25 MPa and 1% FA. Oxidation coefficient had a significant positive effect on the degradation of FA. Total carbon (TC) and TOC removal efficiencies increased from 78.9 % to 97.2 % and from 86.4 % to 97.2, respectively, when oxidation coefficient increased from 0 to 4. Benzene, phenol and naphthalene could be regarded as the intermediate products in SCWO.

Polymer-free VES fluids are used to minimize damage to the proppant pack to efficiently transport proppants into fractures. Proper investigation of the rheological properties and the proppant settling of the fluids play an important role in fracturing enginering.In this paper,the rheology and viscosity-temperature properties of the VES fracturing fluid were researched at the range of 1wt% to 6wt% of VES concentration using the HAAKE RS300 Stress-Controlled Rheometer. Proppant settling experiments are performed in static VES fluid. The results show that VES system behaves as a non-Newtonian shear-thinning fluid and the power law model can be used to describe fluid rheology within a certain range of shear rate and temperature. However, with the increase of shear rate and temperature, the fluid trends to Newtonian fluid. Apparant viscocity of the fluid first increases slightly with the temperature rising from 28°C, then，It would drastically reduce after reaching a peak. The temperature correspongding to the peak value increases with the concentration of VES,as well as the shear rates. When VES concentration is 4wt%, the fluid may generates stable micro-mesh wormlike micelle structure, which results in good viscoelasticity and high proppant-carrying capacity.

Supercritical water oxidation (SCWO) of concentrated landfill leachate has been carried out in a batch reactor in fluidized bed sand bath, operated under varied temperature (450-600 °C), pressure (23-29 MPa), residence time (5-20 min) and oxidation coefficient (1.5-3.0). The experimental results indicated that temperature and oxidation coefficient had significant influences on the oxidation reaction, whereas the pressure and residence time were not crucial factors. The chemical oxygen demand (COD) and ammonia nitrogen (NH4-N) removal efficiencies could reach up to 99.23% and 98.64% at 600 °C, 25 MPa and 5 min with a oxidation coefficient of 2, respectively, and the effluents could be discharged harmlessly.

The oxidation of methanthiol and thiirane in supercritical water was explored by using a tubular-flow reactor system using oxygen as oxidant. No sulfur containing species existed in the gaseous effluent. Sulfide, sulfite and sulfate were detected as the sulfur containing species in the liquid effluent for supercritical water oxidation (SCWO) of methannthiol, while it was determined as thiosulfate, sulfite and sulfate for SCWO of thiirane. When reaction temperature exceeded 873K, the sulfur contained in the methanthiol or thiirane all transformed into the liquid products. Oxidant stoichiometric ratio had little effect on the conversion rate of sulfur but could promoted sulfite converted into sulfate. Sulfide and thiosulfate were determined as the exclusive sulfur containing product arising directly from methanthiol and thiirane, respectively. The transformation pathways of sulfur contained in the methanthiol and thiirane were proposed as methanthiol-sulfide-sulfite-sulfate and thiirane-thiosulfate-sulfite-sulfate, respectively.

Supercritical water oxidation in hydrothermal flames is a promising method for the total destruction of refractory compounds because it can overcome corrosion and salt deposition problems. In case of wastewater with a low reaction heat, the use of auxiliary fuels, to increase the reaction heat for the auto thermal operation is necessary. Methanol and isopropyl-alcohol were usually used as fuels. This paper compares the two fuels in hydrothermal flames and reviews the experimental results of salts, acetic acid, dioxins, ammonia, sludge and phenols of naphthalene and toluene. The results show that the destruction process obtains high TOC removals, and phenols are easy to cause soot formation problems. If soot deposition problems can be solved, supercritical water oxidation in hydrothermal flames will have a bright prospect for commercial applications.