Synthesizing Equivalence Indices for the Comparative Evaluation of Technoeconomic Efficiency of Industrial Processes at the Design/Re‐engineering Level Available to Purchase

The equivalence indices synthesized for the comparative evaluation of technoeconomic efficiency of industrial processes are of critical importance since they serve as both, (i) positive/analytic descriptors of the physicochemical nature of the process and (ii) measures of effectiveness, especially helpful for investigated competitiveness in the industrial/energy/environmental sector of the economy. In the present work, a new algorithmic procedure has been developed, which initially standardizes a real industrial process, then analyzes it as a compromise of two ideal processes, and finally synthesizes the index that can represent/reconstruct the real process as a result of the trade‐off between the two ideal processes taking as parental prototypes. The same procedure makes fuzzy multicriteria ranking within a set of pre‐selected industrial processes for two reasons: (a) to analyze the process most representative of the production/treatment under consideration, (b) to use the ‘second best’ alternative as a dialectic pole in absence of the two ideal processes mentioned above. An implantation of this procedure is presented, concerning a facility of biological wastewater treatment with six alternatives: activated sludge through (i) continuous‐flow incompletely‐stirred tank reactors in series, (ii) a plug flow reactor with dispersion, (iii) an oxidation ditch, and biological processing through (iv) a trickling filter, (v) rotating contactors, (vi) shallow ponds. The criteria used for fuzzy (to count for uncertainty) ranking are capital cost, operating cost, environmental friendliness, reliability, flexibility, extendibility. Two complementary indices were synthesized for the (ii)‐alternative ranked first and their quantitative expressions were derived, covering a variety of kinetic models as well as recycle/bypass conditions. Finally, analysis of estimating the optimal values of these indices at maximum technoeconomic efficiency is presented and the implications (expected to be) caused by exogenous and endogenous factors (e.g., environmental standards change and innovative energy savings/substitution, respectively) are discussed by means of marginal efficiency graphs.