Sewage sludge-based functional nanomaterials: development and applications

Sewage sludge, the major by-product of wastewater treatment plants, is defined as a pollutant by the US Environmental Protection Agency. The increasing production of sewage sludge worldwide and the imposition of more stringent regulations, together with the restriction of traditional options for sewage sludge disposal, have prompted new approaches for the cost-effective and environmentally benign treatment and reuse of sewage sludge. This paper seeks to review the published research on the development and applications of sewage sludge-based functional nanomaterials. The production methods of nanomaterials are illuminated, and the textural properties of the as-prepared nanomaterials are summarized. The potential applications of the as-prepared nanomaterials in the fields of pollutant degradation and electrochemical energy storage and conversion are reviewed. The synergistically enhanced performances between the as-synthesized nanomaterials and the specific small inorganic molecular or metal oxides in sewage sludge are discussed. Furthermore, the future opportunities and challenges in this emerging research area of designing functional nanomaterials from sewage sludge are addressed.