Four intricated lines perform the Water2Return circle: the water line, where wastewater produced at the slaughterhouse ‘Matadero del Sur‘ (Salteras, Spain) is treated, producing a concentrate of nutrients (product #1) and sludge; the sludge line, where water line’s sludge is sanitised and fermented with Bacillus sp., producing a Bacillus biomass (product #2) and hydrolysed sludge; the energy recovery module, where sludge line’s hydrolysed sludge is digested to produce energy (product #3) and release CO2; and the algae line, where energy recovery module’s released CO2 is captured to feed the microalgae under cultivation, producing an algal biomass (product #4), and water line’s treated water can be also used to fill in the algae ponds. This article focuses on the development of the water line, from source to end.
