Supercritical water gasification of industrial organic wastes

Abstract

Supercritical Water Gasification (SCWG), in which supercritical water is not only a solvent for organic materials but also a reactant, is one of the applications for producing fuel from organic resources. In this way, besides the destruction of wastewaters, it is aimed to harness their energy potential by burning the gas effluent generated in the process, which contains a high level of heating power due to its high content in hydrogen and light hydrocarbons. In the work described here, SCWG has been tested on a laboratory scale continuous-flow system with two different industrial wastewaters that contain a high concentration of organics, with both wastes having a high energy potential: cutting oil wastes, oleaginous wastewater from metalworking industries, and vinasses, alcohol distillery wastewater. Reports on SCWG processes on these types of wastewaters have not previously been published in the literature. The influence of the temperature, amount of oxidant and catalyst addition on the yield and composition of the gas phase generated were studied. Experiments were carried out in the temperature range 450–550 °C, the amount of oxidant ranged from the absence of oxygen (oxygen coefficient, n = 0) to 20% of stoichiometric oxygen ( n = 0.2), and 250 bar of pressure in all cases. A maximum of 0.19 mol H 2 per initial COD m (COD m is given as mol O 2 consumed for total oxidation) was obtained in the gas phase under the best conditions.