You’ve listed costs for different treatment methods, but the units and currencies are all over the place. For example:
Constructed wetlands: $420–$1,730 for 10,000 gpd
MFCs: $6,064 for 1 tonne
Anaerobic digestion: €28,357.709 for 1820/m³
Trickling filter: $23,663,119.96 for 200,000 M/day (is “M³” m³?)
Some costs are in USD, some in Euros, capacities are in gpd, tonnes, m³, M/day… without standardization or even a note on currency conversion or capacity normalization, how can you fairly compare them? This makes the cost comparison pretty misleading.
Also, the anaerobic digestion cost looks suspiciously high, €28 million? Is that a typo? Maybe it’s meant to be €28,357.709, but even then, the decimal places are inconsistent.
If these numbers aren’t corrected or explained, the whole economic argument falls apart. Did you use a common baseline (e.g., cost per m³ treated) or just report values as found in the literature? A quick note on methodology or unit conversion would help a lot.