Comparative life-cycle assessment of biological and membrane-based technologies for wastewater treatment in a brewery

A new generation of integrated fixed-film activated sludge (IFAS) systems, merging the biofilm of the root zone from aquatic plants into the activated sludgeprocess, has increasingly gained attention in recent years as a potential alternative to conventional wastewater treatment systems. However, there is a lack of understanding of the broader environmental impact of this emerging technology and how it compares to traditional concepts of wastewater treatment. In this research, we address this gap by conducting a comparative Life Cycle Assessment (LCA) with three reference scenarios, based on design simulations in seven midpoint impact categories. The entire novel wastewater treatment system at a small to medium-sized brewery in the Netherlands, including sludge disposal, resulted in net values of 29.2 MJ, 1.9 kg CO2-eq., 3.4 g  OX-eq., 0.1 mg CFC11- eq., 4.0 g SO2-eq., 0.3 g P-eq., and 1.9 N-eq. per m3 wastewater treated, under categories CED, GWP, POFP, ODP, TAP, FEP, and MEP, respectively. Compared to aerated SBR systems, the new system demonstrated higher environmental burdens in CED (120%), GWP (122%), POFP (125%), ODP (123%), and TAP (133%). This study provides evidence that these impacts on the environment mainly depend on the technology’s current electricity demand, while additional improvements can also be achieved by lowering the chemical and nutrient demand of the system. The comparison to a potential anaerobic treatment opportunity for the brewery wastewater with an EGSB reactor, exacerbated the previously identified shortcomings of the new technology, since the crediting of biogas allowed a complete offset of the total environmental impact measured by the GWP, CED, and ODP. Our findings suggest that additional water recovery concepts with subsequent nanofiltration systems, aimed at preserving natural water resources, may offer no competitive advantage for the GWP, CED, POFP, OPD, and TAP, if the electricity demand (1.17 kWh per provided m3 reused water) surpasses the benefit of water reuse. However, it is important to note that the new technologies provide their own set of benefits, such as a reduced impact on freshwater and marine eutrophication, due to the high  nutrient uptake capability. Our research provides implications for practitioners and researchers seeking to understand the environmental impact associated with plant root equipped IFAS, while implicit design assumptions may limit the ability to generalise findings on real-world scenarios.

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