The life cycle inventory data for M1 and M2 are summarised in Tables and. All the input and output data were primary data collected from experiments performed at the Membrane Science and Separation Technology Division, CSIR-CSMCRI. The data were imported to the openLCA software and associated with the Ecoinvent 3.7 database. It should be noted the database lacks data for a few chemicals. To fill the data gap, a suitable proxy was selected based on the literature and the molecular structure and properties of the considered chemical . First, PVDF was substituted with tetrafluoroethylene (TFE) and polyethene (PE) in a 50:50 ratio according to previous publications . Second, the following chemicals were replaced with proxies of similar structure/properties (in parenthesis): basic and neutral alumina (refractory aluminium oxide), chloromethyl styrene (styrene), PEI (triethylamine), H3CO-PEG-OH (ethylene glycol monoethyl ether), HMDI (toluene diisocyanate), DCM (methane, dichloro-, and HCC-30), and NH2-PDMS-NH2 (PDMS). Although the use of proxies enables qualified estimations of the environmental impacts of chemicals, it tends to underestimate the environmental impacts and thus the results should be taken with caution .