Nutrient recovery in domestic wastewater treatment has increasingly become an important area of study as the supply of non-renewable phosphorus decreases. Recent bench-scale trials indicate that co-generation of struvite and hydrogen using electrochemical methods may offer an alternative to existing recovery options utilized by municipal wastewater treatment facilities. However, implementation has yet to be explored at plant-scale. In the development of novel nutrient recovery processes, both economic and environmental assessments are necessary to guide research and their design. The aim of this study was to conduct a prospective life cycle assessment and cost analysis of a new electrochemical struvite recovery technology that utilizes a sacrificial magnesium anode to precipitate struvite and generate hydrogen gas. This technology was modeled using process simulation software GPS-X and CapdetWorks assuming its integration in a full-scale existing wastewater treatment plant with and without anaerobic digestion. Struvite recoveries of 18–33% were achieved when anaerobic digestion was included, with a break-even price of $6.03/kg struvite and $15.58/kg of hydrogen required to offset increased costs for recovery. Struvite recovery reduced aquatic eutrophication impacts as well as terrestrial acidification impacts. Tradeoffs between benefits from struvite and burdens from electrode manufacturing were found for several impact categories.
Techno-Economic Analysis and Life Cycle Assessment of Hydroxylamine Eco-Manufacturing via Wastewater Electrochemical Reduction
There is a growing need to develop novel technologies that reduce reactive nitrogen concentrations in wastewater streams and decrease our reliance on fossil fuel energy required to produce N-based chemicals and fertilizers. This study conducts a techno-economic analysis (TEA) and a life cycle assessment (LCA) of the electrochemical conversion of nitrate ions (NO3–) present in wastewater to hydroxylamine (NH2OH), a valuable chemical intermediate. We employ experimental data and modeling assumptions to determine NH2OH production costs and life cycle emissions for a small-scale facility (producing 1500 kg-NH2OH/day) and a large-scale facility (producing 50,000 kg-NH2OH/day) integrated into a wastewater treatment plant. The present NH2OH production costs for the small- and large-scale facilities are estimated at $6.14/kg-NH2OH and $5.37/kg-NH2OH, respectively. The parameters dominating the electrochemical reactor cost are electrolyte, separations, and fixed cost, with their values as $1.48, $0.96, and $0.53/kg. Future cost reduction projections indicate that the present NH2OH production costs for the small- and large-scale facilities can be reduced to $2.79/kg-NH2OH and $2.06/kg-NH2OH (NH2OH market price = $1.72/kg), respectively, with improvements in the sensitivity analysis parameters. LCA results indicate that the proposed electrochemical pathway to produce NH2OH has lower life cycle impacts than the conventional pathway.
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- Award ID(s):
- 2036944
- NSF-PAR ID:
- 10457276
- Date Published:
- Journal Name:
- ACS sustainable chemistry engineering
- Volume:
- 11
- Issue:
- 37
- ISSN:
- 2168-0485
- Page Range / eLocation ID:
- 13636-13645
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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