Hydrogen production from wastewater

A method of producing hydrogen (H2) and clean water from a wastewater stream, the method comprising:

• feeding a wastewater stream to a reserve osmosis (RO) system, the wastewater stream comprising organic and inorganic contaminants and originating from an oil refinery plant;
• using the RO system, concentrating the organic and inorganic contaminants in the wastewater stream, forming a concentrated retentate stream;
• pressurizing the concentrated retentate stream to a pressure above 20 MPa;
• heating the concentrated retentate stream to a temperature above 350° C.;
• feeding the pressurized and heated concentrated retentate stream to a salt separator to separate the inorganic contaminants from the pressurized and heated concentrated retentate stream, generating a salt-free wastewater stream;
• heating the salt-free wastewater stream to a temperature above 400° C.;
• converting the salt-free wastewater stream into a methane-containing gasification product under a supercritical condition using a first reactor;
• and
• reforming the methane-containing gasification product using a second reactor comprising a reforming catalyst to produce a product stream comprising H2, carbon dioxide (CO2), and water vapor.

A wastewater treatment system comprising:

• a salt separator to separate inorganic contaminants from a wastewater steam comprising organic contaminants and the inorganic contaminants;
• a first reactor, fluidically connected and downstream to the salt separator, to perform hydrothermal gasification of the wastewater stream and product a methane-containing stream;
• a second reactor, fluidically connected and downstream to the first reactor, to perform a reforming reaction of the methane-containing stream under a supercritical condition and produce a product stream comprising hydrogen (H2), carbon dioxide (CO2), and water vapor;
• a gas liquid separation unit, fluidically connected and downstream to the second reactor, to separate the CO2 and the water vapor;
• and
• a computer processor comprising a non-transitory computer readable medium storing instruction to
• feed the wastewater stream to the salt separator under a sub- or supercritical condition,
• feed the wastewater stream to the first reactor under a sub- or supercritical condition, and
• separate the H2 from the product stream.