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Project title

GreenCOD – Investigating green methodologies for the routine measurement of Chemical Oxygen Demand

Primary Funding Agency

Environmental Protection Agency (EPA)

Co-Funding Organisation(s)

n/a

Lead Organisation

Munster Technological University (MTU)

Lead Applicant

Patrick Quille

Project Abstract

The Chemical Oxygen Demand (COD) represents the level of organic pollution in water bodies and thus is a critical analytical parameter for water quality assessment that is carried out on samples from a variety of sources. The current accepted method in Ireland for determining COD utilises several toxic and carcinogenic substances, including strong acids and mercury sulphate in a digestion mixture, together with potassium chromate as an oxidising agent. The current method, therefore, represents a significant risk to lab workers while also presenting an enormous environmental and financial burden in their correct disposal. Several alternative and greener methods for determining COD have been described in the literature and are used for measuring water quality in other jurisdictions. These range from using electrochemical oxidation to alternative digestion and oxidising agents, and the use of indirect measures for COD. However, the success, accuracy and ultimately usefulness of each of these tests is determined by the sample source (that dictates the range of possible interferences) and inherent level of COD of the sample. Therefore, the GreenCOD project proposes to assess a range of alternative methods for measuring the COD of a variety of samples from different sources with the ultimate aim of recommending a replacement test(s) together with associated methods. To achieve this, the research plan is broken into separate but interconnected objectives: • To gather and assess the approximate number of samples analysed annually for COD in Ireland, as well as their origin and raw COD value. The background of a sample will have an important bearing on assessing the potential of alternative methods due to interferences, such as chloride levels, as will the actual COD value. • Carry out a review of best practices in different jurisdictions (worldwide) to determine COD across different sample types. • Assess the viability of a range of alternative methods to the current mercury and dichromate standard method. Viability will be assessed based on several defined parameters: cost (running and capital), safety, throughput, robustness (in terms of sample type) and finally, statistical analysis and accuracy. o Alternative wet chemical methods, including the use of AgCl precipitation before using permanganate oxidation. This objective will also entail investigating the digestion procedure to minimise interferences. o Potential electrochemical and photoelectrocatalytic methods to use advanced oxidation procedures for the organic fraction before measuring the resulting signal. o Using Total Organic Carbon (TOC) as an indirect measure for COD. To achieve these specific objectives, detailed SOPs will be written to assess cost and throughput, while accuracy and robustness will be measured by comparing alternative methods to results from current conventional method. On completion of the project, the project will deliver a final policy document to regulatory laboratories and standardisation bodies, including the European Reference Laboratories and ISO, to inform policy discussion.

Grant Approved

€133,000.00

Research Hub

Delivering a Healthy Environment

Research Theme

n/a

Start Date

31/03/2026

Initial Projected Completion Date

30/03/2028