Significance and Use
5.1 This test method describes a rapid method to determine the maximum quantity of oxygen that may be consumed by impurities in water. As outlined in Test Methods , chemical oxygen demand is typically used to monitor and control oxygen-consuming pollutants, both organic and inorganic, in domestic and industrial wastewaters. This photoelectrochemical oxygen demand test method is specific for measuring organics and inorganics in freshwater sources for drinking water treatment plants and treated drinking water matrices. This photoelectrochemical oxygen demand test method is not intended for domestic and industrial wastewaters to replace Test Methods .
5.2 This test method does not require the use of the hazardous reagents, such as mercuric sulfate, potassium dichromate and silver sulfate, that are associated with chemical oxygen demand. It can also provide a result more rapidly than chemical oxygen demand as samples do not require reflux.
1.1 This test method covers a protocol for the determination of the photoelectrochemical oxygen demand of freshwater sources for drinking water treatment plants and treated drinking water in the range of 0.7 mg/L to 20 mg/L. Higher levels may be determined by sample dilution.
1.2 Photoelectrochemical oxygen demand is determined using the current generated from the photoelectrochemical oxidation of the sample using titanium dioxide (TiO2) irradiated with ultraviolet (UV) light from a light-emitting diode (LED).
1.3 This test method does not require the use of the hazardous reagents, such as mercuric sulfate, potassium dichromate and silver sulfate, that are often associated with the determination of chemical oxygen demand (that is, Test Methods ). It can also provide a result rapidly, as samples do not require reflux.
1.4 Determination of photoelectrochemical oxygen demand in freshwater sources for drinking water treatment plants and treated drinking water matrices has important implications for assessing treatment efficacy. Photoelectrochemical oxygen demand can be used as a bulk surrogate measure of natural organic matter, a key target for drinking water treatment. In aerobic biological treatment processes, determination of photoelectrochemical oxygen demand can provide an estimation of the oxygen required by microorganisms to degrade organic matter. This test method is complementary to existing natural organic matter (NOM) monitoring techniques and will help scientists and engineers further the understanding of NOM in water with a rapid oxygen demand test.
1.5 This test method was used successfully with reagent grade water spiked with pure compounds, freshwater sources for drinking water treatment plants and treated drinking water. It is the user’s responsibility to ensure the validity of this test method for waters of untested matrices.
1.6 This test method is applicable to oxidizable matter, <50 µm that can be introduced into the sensor.
Note 1: This test method can be performed (1) immediately in the field or laboratory on an unpreserved sample, and (2) in the laboratory on a properly preserved sample following the stated hold times.
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section .
1.9 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.