Quantitative analysis of anaerobic and phototrophic treatment technologies to advance resource recovery from wastewaters

The overarching goal of this dissertation was to further the development of alternative (i.e., anaerobic and phototrophic) wastewater treatment technologies to fully realize the potential chemical energy of wastewater and to improve the environmental and economic sustainability of wastewater infrastructure. Anthropogenic activities are negatively impacting the environment through biodiversity loss, altering nutrient cycles, and increases in severe weather events. These impacts are subsequently hindering the ability of water resource recovery facilities to protect human and environmental health. Current wastewater treatment is primarily based on the cultivation of aerobic heterotrophs and, although it provides a high-quality effluent, it is also energy intensive. High energy demand is costly both economically and environmentally. These problems underlie a need to re-envision municipal wastewaters as a renewable resource for nutrients and energy while continuing to hold human and environmental health paramount. This research addresses a critical barrier to technological advancement and adoption of mainline anaerobic and phototrophic technologies: a lack of understanding of how to design and model these processes to provide consistently high-quality effluent while reducing the environmental and economic impacts of alternative technologies. Though wastewater has a high inherent energy content, organic carbon is typically degraded to CO2 and emitted to the atmosphere. Recovering and valorizing wastewater organic carbon is therefore critical in order to make wastewater treatment economically and environmentally viable in the future. To this end, an in-depth examination of anaerobic membrane bioreactor (AnMBR) designs was conducted utilizing quantitative sustainable design to elucidate the economic and environmental implications of 150 system configurations, prioritizing research and development pathways to improve system sustainability. The results show that membrane-related design decisions (e.g., material, configuration, etc.) have a profound impact on the net present cost and life cycle environmental impacts. Therefore, recommendations for future research are made that prioritize AnMBR configurations with the greatest potential for full-scale success. While AnMBRs are shown to have potential to valorize organic carbon, this technology is ineffective for nutrient recovery. Given this, phototrophic technologies (e.g., photobioreactors) can be used to recover nutrients, but current modeling capabilities for phototrophic systems are limited. Current models are frequently inaccurate and complex, inhibiting the broad adoption of phototrophic technologies. To this end, a large-scale critical review and statistical assessment of models for microalgae cultivation were performed. Results of the critical review show that there are many disparate models for microalgal metabolism, necessitating a comparison of these model structures to determine a path forward for algae modeling. The models extracted from the critical review were then compared using reconciled data from a pilot-scale photobioreactor treating secondary effluent. In total, sensitivity of 44 parameters was assessed for each of 288 models, which then informed which parameters to use when calibrating and validating a given model. Results show that model equations should be chosen carefully to balance computational complexity with accuracy. Altogether, these modeling tools and assessments elucidate a pathway to the integration of anaerobic and phototrophic treatment systems for the recovery of resources from wastewaters