Rapid Source & Treated Water Quality Testing Using Chemical Oxygen Demand
On June 1, 2018 MANTECH representative Justin Dickerman gave a presentation at the Ontario Water Works Association (OWWA) Ottawa Seminar event. He shared information about rapid source and treated water quality testing using chemical oxygen demand with government officials, industry leaders, and academics.
Drinking water treatment is one of the main safeguards of public health, and utilities are under constant pressure to improve. There is movement towards online monitoring systems for event detection, with a focus on natural organic matter (NOM). Traditional online technologies, such as total organic carbon (TOC), UV absorbance at 254 nm (UV254), and specific UV absorbance (SUVA) are not providing the full picture of organic compounds in the water.
Natural organic matter (NOM) is a critical target for drinking water treatment. The presence of NOM causes many challenges in drinking water treatment processes, including:
- Taste, colour, and odor issues
- Increased coagulation and disinfection dose
- Increased fouling, requiring more frequent backwashing
- Increased sludge production
- Promotes biological growth in distribution systems
NOM compounds are known to react with common disinfectants to produce harmful and potentially carcinogenic disinfection by-products (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs). Utilities require a parameter that provides them with information on treatment efficiency, NOM removal, and potential for DBP formation. Existing NOM surrogates pose many challenges, and may not be well suited. For example, total organic carbon (TOC) and dissolved organic carbon (DOC) do not quantify reactive organic species. They do not represent the electron-donating capacity of a compound, and can be difficult to implement. Furthermore, UV254 and SUVA rely on aromaticity, which is not a chemical feature of all organic compounds. These surrogates also require matrix-specific calibration, and can be difficult to compare results between locations.
Chemical oxygen demand (COD) is used as a measurement of the oxygen-depletion capacity of a sample contaminated with organic waste. COD measures the reactivity, or oxidisability, of organic contamination (i.e. NOM that is a potential precursor for DBPs). The photoelectrochemical oxygen demand (peCOD) method provides fast and accurate results in less than 10 minutes.
Learn more about how peCOD provides increased sensitivity versus traditional parameters in the full presentation here.