Hydrogen Production by Solar Photoreforming of Urban Wastewaters in Thin‐Layer Flat Catalytic Panels

Abstract The effective simultaneous production of hydrogen and removal of organic pollutants by solar photoreforming of various real urban wastewater effluents using a Pt/TiO 2 photocatalyst is proven. Initial testing in laboratory‐scale batch photocatalyst suspensions experiments, under both UV and simulated sunlight, result in photocatalytic H 2 production (along with variable CO 2 amounts) from urban wastewaters; photoreforming efficiency decreases in the following order: influent stream > primary sludge > final sludge. Hydrogen evolution exceeds 1500 µmol g cat −1 after 3 h under UV. Further development is undertaken in an outdoors pre‐pilot‐plant scale flat solar panel reactor having a thin layer of photocatalyst (7 g m −2 , thickness: 4–30 µm) exposed to natural sunlight. The proof‐of‐concept solar photoreforming of an influent urban sewage stream in the flat solar panel proceeds with remarkable activity and stability for almost one month (27 d, irradiation time ≈160 h). Despite operated in late autumn at 41.1 ° North latitude, gas production is sustained and consistently correlated with solar irradiances (600–900 W m −2 ). Furthermore, wastewater decontamination is proven by sustained decrease in chemical oxygen demand and pH, whereas conductivity tended to increase slightly, most likely owing to the breakdown of complex organic matter.