Life cycle energy, climate, and economic assessment of technologies for bioresource production from wastewater

Abstract Thermochemical conversion technologies present an opportunity to flip the paradigm of wastewater biosolids management operations from energy-intense and expensive waste management processes into energy-positive and economical resource extraction centers. Herein, we present a uniform “grading framework” to consistently evaluate the environmental and commercial benefits of established and emerging wastewater biosolids management processes from a life cycle and techno-economic perspective. Application of this approach reveals that established wastewater biosolids management practices such as landfilling, land application, incineration and anaerobic digestion, while commercially viable, offer little environmental benefit. On the other hand, emerging thermochemical bioresource recovery technologies such as hydrothermal liquefaction, gasification, pyrolysis, and torrefaction show potential to provide substantial economic and environmental benefit through the recovery of carbon and nutrients from wastewater biosolids in the form of biofuels, fertilizers, and other high-value products. Some emerging thermochemical technologies have developed beyond pilot scale although their commercial viability remains to be seen.