Comparative Life Cycle and Technoeconomic Assessment for Energy Recovery from Dilute Wastewater
Environmental Engineering Science
Civil and Environmental Engineering
Anaerobic treatment offers a sustainable alternative to aerobic treatment by recovering energy from wastewater. Anaerobic treatment, however, is challenged by reduced performance at lower temperatures and dissolved methane in the effluent, which represents a loss in recoverable energy and a potent greenhouse gas emission. Long-term operation of a bench-scale anaerobic baffled reactor (ABR) at 15-20 degrees C, with domestic wastewater, provided data to evaluate life cycle environmental and economic performances of mainstream anaerobic treatment. Performance of theABRwas compared to a conceptual design of treatment with trickling filter+anaerobic digestion (TF+AD). The ABR and TF were modeled as example low-cost anaerobic and aerobic treatments, respectively, because these technologies may be more easily implemented (compared to membrane systems and activated sludge) in developing countries. This type of comprehensive study, not conducted previously for the ABR, is imperative for selecting appropriate technologies as we determine how to bring sanitation to billions who are unserved. The ABR recovered approximately six times more energy from low-strength wastewater than TF+AD and resulted in significantly more beneficial life cycle impacts for ecosystem quality and human health. Furthermore, techno-economic analysis showed that the ABR has a life cycle cost that is about 40% lower than TF+AD. Dissolved methane in the effluent of the ABR, however, resulted in a harmful impact on climate change, whereas TF+AD resulted in approximately neutral impacts on climate change. Acombined ABR+TF assembly, which was assumed to oxidize residual organics and dissolved methane, resulted in beneficial environmental impacts for four environmental categories. Advancements in synergistic technologies that remove or recover dissolved methane in anaerobic effluent would allow implementation of the ABR without increasing climate change impacts.
Sills, Deborah L.; Wade, Valerie L.; and DiStefano, Thomas D.. "Comparative Life Cycle and Technoeconomic Assessment for Energy Recovery from Dilute Wastewater." Environmental Engineering Science 33, no. 11 (2016) .