Project Details Standardization of electrical energy per order (EEO) reporting for UV/H2O2 reactors

Project No.:
Start Date:
01 September 2016
End Date:
Division Name:
Chemistry and the Environment Division
Division No.:


The electrical energy per order (EEO) parameter is used to determine the efficiency of UV/H2O2 systems for treatment or organic contaminants. EEO is defined as the number of kilowatt-hours (kWh) of electrical energy required to reduce the concentration of a pollutant by one order of magnitude (90%) in one cubic meter of contaminated water. The parameter was adopted by IUPAC for photochemical reactor characterization is often improperly used or reported without sufficient supporting information. The objective of this work is to clarify the parameters that affect the EEO value for UV/H2O2 advanced oxidation and provide guidelines for its reporting and use. The document will clarify the misconceptions about the EEO to photochemistry researchers and practitioners, and will encourage proper reporting to improve sharing research results.


The Electrical Energy per Order (EEO) is a useful concept for comparing the performance of ultraviolet (UV) based advanced oxidation processes (AOPs) for the degradation of organic contaminants or other applications. The parameter was introduced in 2001 by Bolton et al. in a report published by the IUPAC Photochemistry Commission. It is a fundamental concept, and if properly reported, can be used for comparing technologies based on reports and papers from various years regardless of the energy costs in a given year.

However, the usability of the EEO values, as reported by researchers, is undermined by incomplete reporting. The EEO parameter depends on a variety of factors, from the concentration and the identity of the target contaminant to the amount of hydrogen peroxide added. Therefore, the EEO parameter needs to be reported in AOP literature together with many other experimental details that affect the reactor performance for proper comparison between reactors across studies.

This work will identify the parameters that affect the EEO outcome and need to be reported along with the EEO values. The report will explain how to adjust the results of the different studies for comparison. Ways to standardize the reactor testing and results reporting will be proposed. The report will discuss the proper application of the EEO parameter for bench-, pilot- and full-scale studies. The proposed notation also will be reiterated.

The work builds on the prior IUPAC report by Bolton et al. (2001) that introduced EEO. The goal of the report is further standardization of measuring and reporting EEO, and as such it falls within the IUPAC mission of creating a standard communication protocol for experimental outcomes so that the results could be widely used and shared.

Bolton J.R., Bircher, K.G., Tumas W. and Tolman, C.A. (2001) Figures-of-merit for the technical development and application of advanced oxidation technologies for both electric- and solar-driven systems (IUPAC Technical Report). Pure and Applied Chemistry 73(4), 627-637


Dec 2016 – Project announcement published in Chem. Int. Nov 2016, p. 24;

May 2018 – A Technical Report titled ‘Standard reporting of Electrical Energy per Order (EEO) for UV/H2O2 reactors’ is published in Pure App. Chem. 90(9), pp. 1487-1499 (

Page last update 11 Sep 2018