(646c) Systematic Evaluation of Emerging Wastewater Nutrient Removal and Recovery Technologies to Inform Practice and Advance Resource Efficiency

Nutrient discharges from wastewater treatment plants to the environment cause widespread eutrophication (algae overgrowth), harming aquatic life and resulting in economic losses. Conventional nutrient removal from wastewater can prevent these negative impacts but requires substantial energy and chemical inputs. Meanwhile, synthesis of ammonia via the Haber-Bosch process and phosphorus mining have substantial environmental footprints and deplete natural resources. Nutrient (nitrogen and phosphorus) recovery technologies could offset chemical production and reduce impacts of the wastewater and chemical industries. Widespread implementation of novel, more efficient nutrient removal and recovery technologies typically takes decades. We systematically reviewed 157 nutrient technologies spanning diverse mechanisms and stages of development and proposed a framework for standardized reporting and comparison of nutrient technologies to accelerate adoption. Our specific objectives were to: (1) characterize and compare nutrient technologies by a common set of qualitative attributes and quantitative performance metrics; (2) identify mismatches between academic literature and the needs of practitioners; and (3) catalogue value propositions, barriers, and knowledge gaps to prioritize future research objectives.

Methods

We extracted information about 157 nutrient technologies from articles in peer-reviewed journals, conference proceedings, and industry reports using a data collection template devised to capture all data needed for our analysis. We recorded reported quantitative performance metrics, value propositions, barriers to adoption, and knowledge gaps. In addition, we conducted a survey of practitioners in the wastewater industry to understand practitioners’ needs, collecting 54 responses predominantly from public wastewater utilities.

Results and Implications

Our review indicated diversity in mechanisms (biological, physicochemical, both), nutrient(s) addressed (nitrogen, phosphorus, both), and treatment objectives (removal, recovery) of nutrient technologies. To facilitate meaningful analysis, we created 38 process groups consisting of similar processes. The observed heterogeneity complicates comparison among technologies. Therefore, we proposed quantitative performance metrics (i.e., removal and recovery efficiency, removal and recovery rate, energy consumption, cost, greenhouse gas emissions, effluent concentration) and qualitative attributes (e.g., technology readiness level, adaptation level required). These metrics constitute a minimal set that is generalizable across all nutrient technologies and facilitates multi-faceted comparisons (e.g., using an overall treatment score based on multiple metrics). Comparing peer-reviewed literature with practitioner needs revealed limited reporting of energy consumption and cost, indicating misalignment between research and practice (Figure 1). Synthesizing barriers to adoption and knowledge gaps reported in literature and by practitioners, we propose a research agenda addressing the most reported gaps (e.g., underlying process mechanisms, scale-up, optimization of reactor configuration and operating conditions) and emphasizing rigorous investigations of systems-level impacts and product-market fit. This study’s results will drive interdisciplinary research on nutrient technologies, guide technology development by academics and practitioners, and accelerate implementation for resource-efficient nutrient management, including recovery technologies.