Solar-driven sewage sludge electroreforming coupled with biological funnelling to cogenerate green food and hydrogen

Abstract

The ever-increasing generation of sewage sludge in megacities places a substantial burden on waste treatment systems. The complex and resilient structure of sludge renders conventional pretreatment and biological reclamation methods time-consuming, energy-inefficient and environmentally burdensome. Here we present an integrated mechano-electro-bioprocess that valorizes sludge with minimal environmental impact. We achieve nearly complete recovery of organics with ~91.4% total organic carbon (TOC), which are effectively converted into single-cell protein (>63% TOC) in a tandem process. Heavy metals are efficiently concentrated and stabilized, while simultaneously producing green hydrogen at an impressive efficiency and rate (~10% solar-to-hydrogen energy efficiency, rate >13 l per hour). A comprehensive life-cycle and techno-economic analysis confirms the substantial environmental and economic benefits of this approach. Notably, it results in a 99.5% reduction in CO2 emissions and a 99.3% decrease in energy depletion compared with conventional anaerobic digestion. As renewable electricity deployment expands globally, this mechano-electro-bioprocess offers a promising path towards sustainable development. The integrated process of mechanochemical fractionation-assisted and solar-driven electrochemical reforming, followed by biological funnelling, enables the efficient upcycling of sewage sludge. This process not only co-produces valuable single-cell protein and green hydrogen but also effectively removes heavy metal contaminants.