*2.6.2 Life cycle inventory (LCI)*

Data from the synthesis of Lac-magnetite and the process of wastewater treatment of each micromixer were measured on site. These data collection involved the determination of the relevant flows, use of reagents, emissions, wastes, and energy consumptions for this LCA study. Data concerning distribution of electricity and production of reagents were obtained from the Ecoinvent 3.6 database. Inventory report of this LCA study was mostly based on own laboratory experiments. **Table 1** shows the inventory report of raw materials, water consumption and energy required for the manufacturing of each micromixer and the corresponding operation process for wastewater treatment.

## *2.6.3 Impact assessment*

Life cycle impact assessment (LCIA) aims to calculate the potential environmental and human health impacts associated with the manufacturing and operation of six micromixers for wastewater treatment. This LCIA was carried out with the aid of Ecoinvent 3.6 database. Characterization factors reported by the International Reference Life Cycle Data System (ILCD) method for LCIA were applied as impact assessment tools. In addition, eight impact categories were considered in this study: human toxicity non-cancer effects, human toxicity cancer effects, ecotoxicity freshwater, climate change total, resource depletion of minerals and metals, resource depletion of dissipated water, freshwater and terrestrial acidification, and photochemical ozone formation.

Regarding the assumptions, data concerning environmental impacts included the production of reagents necessary to synthetize the magnetite nanoparticles, i.e., the production of iron chlorides (II) and (III). However, environmental impact data to produce Tetramethylammonium Hydroxide (TMAH) has not been reported yet and therefore was neglected from the LCA analysis.
