Wastewater treatment system capital costs, O&M costs, and land area - which is best?

Selecting the proper wastewater treatment system can be challenging, to say the least. The process involves:

1. Understanding influent makeup, concentration, and volume (flow)
2. Current and anticipated future effluent discharge requirements
3. Potential changes in influent
4. Budgetary constrains for capital expenditure and ongoing operations/maintenance
5. Life expectancy of the treatment system and ability to modify if needed

Recently, I came across an interesting table from Mara & Pearson (1998) comparing capital expense, O&M, and land requirements for various treatment systems. While the figures are in DM (1996), the relative costs can be extrapolated to current figures.