Assessing METland® Design and Performance Through LCA: Techno-Environmental Study With Multifunctional Unit Perspective

Abstract

Conventional wastewater treatment technologies are costly and energy demanding; such issues are especially remarkable when small communities have to clean up their pollutants. In response to these requirements, a new variety of nature-based solution, so-called METland®, has been recently develop by using concepts from Microbial Electrochemical Technologies (MET) to outperform classical constructed wetland regarding wastewater treatment. Thus, the current study evaluates two operation modes (aerobic and aerobic–anoxic) of a full-scale METland®, including a Life Cycle Assessment (LCA) conducted under a Net Environmental Balance perspective. Moreover, a combined technical and environmental analysis using a Net Eutrophication Balance (NEuB) focus concluded that the downflow (aerobic) mode achieved the highest removal rates for both organic pollutant and nitrogen, and it was revealed as the most environmentally friendly design. Actually, aerobic configuration outperformed anaero/aero-mixed mode in a fold-range from 9 to 30%. LCA was indeed recalculated under diverse Functional Units (FU) to determine the influence of each FU in the impacts. Furthermore, in comparison with constructed wetland, METland® showed a remarkable increase in wastewater treatment capacity per surface area (0.6 m2/pe) without using external energy. Specifically, these results suggest that aerobic–anoxic configuration could be more environmentally friendly under specific situations where high N removal is required. The removal rates achieved demonstrated a robust adaptation to influent variations, revealing a removal average of 92% of Biology Oxygen Demand (BOD), 90% of Total Suspended Solids (TSS), 40% of total nitrogen (TN), and 30% of total phosphorus (TP). Moreover, regarding the global warming category, the overall impact was 75% lower compared to other conventional treatments like activated sludge. In conclusion, the LCA revealed that METland® appears as ideal solution for rural areas, considering the low energy requirements and high efficiency to remove organic pollutants, nitrogen, and phosphates from urban wastewater.

Microbial Electrochemically Assisted Treatment Wetlands: Current Flow Density as a Performance Indicator in Real-Scale Systems in Mediterranean and Northern European Locations

“…In the case of Ørby, the organic load from urban wastewater was higher than at IMDEA, but due to seasonal variation, the flow rate was limited to 2 m 3 /day. Both situations revealed organic removal rates lower than other METland studies reported in the literature ( Aguirre-Sierra et al, 2016 ; Prado et al, 2019 ; Ramírez-Vargas et al, 2019 ; Peñacoba-Antona et al, 2021b ). Each system was analyzed independently considering the removal efficiencies based on inlet/outlet concentrations ( Figure 4 ).…”

“…Most recently, Prado et al (2020) reported removals of up to 95% for COD and 71% for TN with the integration of an artificial device, the e-sink, for consuming electrons. These results suggest that the METland system can enhance biodegradation rates, reducing the footprint of classical TWs by 10-fold ( Peñacoba-Antona et al, 2021b ).…”

Water treatment and reclamation by implementing electrochemical systems with constructed wetlands

“…5) while achieving COD removal efficiencies of about 90% [35]. A life cycle assessment (LCA) study suggested that they are an environmentally sustainable wastewater treatment technology [88]. Their optimal locations for implementation have been investigated using geospatial tools like multicriteria evaluation and sensitivity analysis [89].…”

Microbe–Anode Interactions: Comparing the impact of genetic and material engineering approaches to improve the performance of microbial electrochemical systems (MES)

“…Naturally, lab‐scale studies are rarely about the economics of an application, but a life cycle assessment would be one way of investigating at an early stage which technical modifications might have a realistic chance for scale‐up. These life cycle assessment studies have, e.g., been carried out for wastewater treatment processes (Mathuriya, Hiloidhari, Gware, Singh, & Pant, 2020 ; Peñacoba‐Antona et al, 2021 ) and provide information on the economic and ecological viability of the proposed processes. The same applies to the use of carbon or metal‐based materials as the basis for electrodes and to the question of which compounds used for optimization would be economically and ecologically viable.…”