Emerging Technologies for Resource Recovery from Industrial Wastewater Sludge: Advances in Circular Economy Applications

Abstract

Industrial activities produce massive amounts of heterogeneous wastewater sludge. Traditionally, these are handled by unsustainable "cradle-to-grave" linear solutions like landfilling and incineration. This review aims to bridge the identified knowledge gaps with regard to the absence of standardized protocols and comparative evaluations of these emerging solutions by critically evaluating 42 specific studies out of 105,000 sources. Though solutions like Thermal Hydrolysis are well developed and operational, advanced solutions like Microbial Electrolysis Cells are hindered by "valley of death" hurdles like high capital and operational costs and technical instabilities. The novelty of the current review lies in its specific attention to the complex and toxic nature of industrial sludge as opposed to municipal sewage sludge and its integration of Techno-Economic Analysis (TEA) and Life Cycle Assessment (LCA). This review provides a strategic roadmap for "technological leapfrogging," which will be of immense value to stakeholders for transforming sludge into a sustainable economic opportunity aligned with the UN SDGs 6, 11, 12, and 13.