Life cycle assessment as development and decision support tool for wastewater resource recovery technology

Abstract

Life cycle assessment (LCA) has been increasingly used in the field of wastewater treatment where the focus has been to identify environmental trade-offs of current technologies. In a novel approach, we use LCA to support early stage research and development of a biochemical system for wastewater resource recovery. The freshwater and nutrient content of wastewater are recognized as potential valuable resources that can be recovered for beneficial reuse. Both recovery and reuse are intended to address existing environmental concerns, for example, water scarcity and use of non-renewable phosphorus. However, the resource recovery may come at the cost of unintended environmental impacts. One promising recovery system, referred to as TRENS, consists of an enhanced biological phosphorus removal and recovery system (EBP2R) connected to a photobioreactor. Based on a simulation of a full-scale nutrient and water recovery system in its potential operating environment, we assess the potential environmental impacts of such a system using the EASETECH model. In the simulation, recovered water and nutrients are used in scenarios of agricultural irrigation-fertilization and aquifer recharge. In these scenarios, TRENS reduces global warming up to 15% and marine eutrophication impacts up to 9% compared to conventional treatment. This is due to the recovery and reuse of nutrient resources, primarily nitrogen. The key environmental concerns obtained through the LCA are linked to increased human toxicity impacts from the chosen end use of wastewater recovery products. The toxicity impacts are from both heavy metals release associated with land application of recovered nutrients and production of AlCl3, which is required for advanced wastewater treatment prior to aquifer recharge. Perturbation analysis of the LCA pinpointed nutrient substitution and heavy metals content of algae biofertilizer as critical areas for further research if the performance of nutrient recovery systems such as TRENS is to be better characterized. Our study provides valuable feedback to the TRENS developers and identifies the importance of system expansion to include impacts outside the immediate nutrient recovery system itself. The study also show for the first time the successful evaluation of urban-to-agricultural water systems in EASETECH.

Life cycle assessment of high rate algal ponds for wastewater treatment and resource recovery

“…It was mainly due to the NH3 air emissions derived from NH4+ volatilization in HRAPs and to the heavy metals content in the digestate/biofertilizer (emissions to soil). The results are consistent with previous studies that reported increased toxicity in a comparative LCA by integrating a sidestream process into a conventional wastewater treatment facility where microalgae are cultivated, harvested and then used for fertigation (Fang et al, 2016). Furthermore, it was observed that the higher impacts on terrestrial environments are unavoidable in cases where sludge and nutrients from wastewater are recycled and reused in agriculture (Tangsubkul et al, 2005).…”

“…Depletion, Human Toxicity and Terrestrial Ecotoxicity. These impact categories were selected according to the most relevant environmental issues related to wastewater treatment and used in previous LCA studies (Corominas et al, 2013;Fang et al, 2016;Gallego et al, 2008;Garfí et al, 2017;Hospido et al, 2008). Normalisation was carried out in order to compare all the environmental impacts at the same scale.…”

How to Conduct Prospective Life Cycle Assessment for Emerging Technologies? A Systematic Review and Methodological Guidance

“…The topics of food production (n = 4), mobility (n = 2), and biomass production (n = 1) are analyzed as well. Most authors concluded that applying prospective LCA is useful, leads to new insights during the development of new technologies, and can support policymakers in their work [25,26,32,[34][35][36][37]. Zimmermann et al [27] expand this argument in concluding that prospective LCAs lead to a more robust analysis than traditional static LCAs.…”

Control structure design for resource recovery using the enhanced biological phosphorus removal and recovery (EBP2R) activated sludge process

“…algal biomass) and poor in soluble inorganic nutrients -a medium aimed to be used for fertigation (11). The effluent produced by the TRENS system should be harmless to the environment.…”

“…The fraction of influent nitrogen which cannot be recovered via algal cultivation is removed via the completely autotrophic nitrogen removal (CANR) process. TRENS has been demonstrated to be more sustainable than conventional wastewater treatment based on chemical dosing (11).…”