Energy use and carbon footprints differ dramatically for diverse wastewater-derived carbonaceous substrates: An integrated exploration of biokinetics and life-cycle assessment.
Energy neutrality and reduction of carbon emissions are significant challenges to the enhanced sustainability of wastewater treatment plants (WWTPs). Harvesting energy from wastewater carbonaceous substrates can offset energy demands and enable net power generation; yet, there is limited research about how carbonaceous substrates influence energy and carbon implications of WWTPs with integrated energy recovery at systems-level. Consequently, this research uses biokinetics modelling and life cycle assessment philology to explore this notion, by tracing and assessing the quantitative flows of energy embodied or captured, and by exploring the carbon footprint throughout an energy-intensive activated sludge process with integrated energy recovery facilities. The results indicate that energy use and carbon footprint per cubic meter of wastewater treated, varies markedly with the carbon substrate. Compared with systems driven with proteins, carbohydrates or other short-chain fatty acids, systems fed with acetic acid realized energy neutrality with maximal net gain of power from methane combustion (0.198 kWh) and incineration of residual biosolids (0.153 kWh); and also achieved a negative carbon footprint (72.6 g CO2). The findings from this work help us to better understand and develop new technical schemes for improving the energy efficiency of WWTPs by repurposing the stream of carbon substrates across systems.
Research Center for Eco-Environmental Sciences, the Chinese Academy of Sciences, Beijing, 100085, China.|University of Chinese Academy of Sciences, Beijing, 100049, China.
Yanbo
Y
Li
Research Center for Eco-Environmental Sciences, the Chinese Academy of Sciences, Beijing, 100085, China. xuwang@rcees.ac.cn.|State Key Joint Laboratory of Environmental Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, the Chinese Academy of Sciences, Beijing, 100085, China. xuwang@rcees.ac.cn.
Xu
X
Wang
Centre for Water Systems, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, EX4 4QF, UK.
David
D
Butler
Research Center for Eco-Environmental Sciences, the Chinese Academy of Sciences, Beijing, 100085, China.|University of Chinese Academy of Sciences, Beijing, 100049, China.
Junxin
J
Liu
Research Center for Eco-Environmental Sciences, the Chinese Academy of Sciences, Beijing, 100085, China.|Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, the Chinese Academy of Sciences, Beijing, 100085, China.
Jiuhui
J
Qu