Water pollution has grown increasingly severe in recent years, demanding widespread attention. If this issue is ignored, limited freshwater resources will fail to meet water supply demands across the globe. For this reason, regulatory authorities attach great importance to water pollution control and have established emission standards for wastewater discharge. Chemical Oxygen Demand (COD) stands out as one of the core indicators in wastewater monitoring.
Given its vital role in Wastewater Monitoring, it is essential to understand COD. COD refers to the oxygen quantity required for potassium dichromate to oxidize organic matter in one liter of wastewater under strongly acidic conditions. Simply put, it reflects the total concentration of organic substances in water. As a key monitoring parameter, COD quantifies the amount of reducing substances present and mirrors the overall pollution level of a water body. Operators rely on Online COD Analyzers to conduct real-time water quality monitoring and measure organic pollutant concentrations. A higher COD reading indicates more severe organic contamination in the water sample.
Organic pollutants stem from a wide range of industrial sectors, including chemical plants and organic fertilizer manufacturers. Hazardous organic compounds generated via any discharge route must undergo proper treatment. Wastewater can only be released after passing water quality inspections. Untreated organic pollutants tend to adsorb onto sediment at the bottom of water bodies and accumulate over time. This accumulation harms aquatic organisms, and in severe cases, leads to mass die-offs of aquatic life, disrupting aquatic ecosystems in rivers, seas and other water areas.
It should be noted that high COD values do not always result in the aforementioned ecological damage. The actual harm level requires further data analysis, covering factors such as the type of organic matter, its impact on the ecological environment and potential hazards to human health. When detailed component analysis is not feasible, technicians may collect water samples for COD testing at regular intervals. A declining COD reading suggests the majority of reducing substances in the water are readily biodegradable, posing relatively low risks to humans, terrestrial plants and aquatic organisms.
