The least expensive, renewable resources are those that are now disposed as waste. Examples include sludges, manures and other agricultural wastes. Although the total amount of such material can be large, it is geographically dispersed and available at each location in only small quantities, on the order of 10 ton/day. The stoichiometry of the starting material (typically a carbohydrate) is, roughly CH2OH (heating value ~17 MJ/kg according to the Dulong correlation); converting it into a hydrocarbon-like fuel (“CH2”) requires removal of 1 mol of water per carbon in the fuel, i.e., about as much water as fuel (cf Fischer-Tropsch synthesis, which also makes ~1 bbl of water per bbl of fuel). Therefore, the production of the fuel will be accompanied by the production of a considerable quantity of water contaminated with hydrocarbons, and minerals. Its processing requires a smaller scale of technology than is typically deployed in centralized chemical plants or refineries. Intensified processes that operate at ambient conditions of pressure and temperature would facilitate small scale, distributed operations of transforming waste resources. Electrochemically activated processes offer all of those attributes. Here we will report our development of electrochemical processes to address two aspects of the overall remediation of the water: separation of ionic species, and oxidation of the residual organics. For separation of ionic species, we are looking into capacitive deionization but have been initially foiled by the complexation of iron cations by negatively charged chelating complexes. For the water remediation, we are testing electrochemical oxidation, which has been deployed for ameliorating water from dyeing and tanning processes.

Electrochemical remediation of wastewater from the production of renewable fuels

2019 Fall National Meeting

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