Novel uses of the organic fraction of municipal solid wastes for diversified technological applications are reported. A humic acid-like substance (cHAL2) isolated from green urban wastes was tested as a chemical auxiliary for fabric cleaning and dyeing, and as a catalyst for the photodegradation of dyes. The results illustrate the fact that biomass wastes can be an interesting source of products for the chemical market. Process and product development in this direction are likely to offer high economic and environmental benefits in a modern, more sustainable waste treatment strategy