What is BOD and COD?
BOD and COD are measures of how polluted wastewater is. Biochemical oxygen demand (BOD) is the oxygen microbes use to break down organic matter. Chemical oxygen demand (COD) is the oxygen needed to oxidize it chemically. Dairy and food effluent is high in both, and discharge permits limit them.
What it is
Biochemical oxygen demand measures the oxygen consumed by bacteria as they break down organic material in a water sample over a set incubation period. It indicates how much the waste would deplete oxygen in a river or lake.
Chemical oxygen demand uses a strong chemical oxidant to measure the oxygen needed to break down organic and some inorganic material. COD results come back faster than BOD and are usually higher, because more material is oxidized.
In dairy and food plants, milk solids, fats, whey, sugars and cleaning residues raise both values. Product losses to drain show up directly as higher BOD and COD at the effluent treatment plant.
Who it applies to / where it is used
BOD and COD limits appear in discharge consents and permits set by environmental regulators, such as state pollution control boards in India and permitting authorities elsewhere. Limits differ by country, state and receiving water, so operators should check their own consent.
How it is measured / what evidence it needs
Laboratory tests remain the reference method. Online COD or proxy sensors can show trends between lab samples, and flow metering turns concentration into load.
- Lab BOD and COD results at inlet and outlet
- Effluent flow to convert concentration into daily load
- Online COD or UV proxy readings where fitted
- Production and CIP events that explain spikes
- Outlet values against the consent limits
How Aqueduct helps
Aqueduct puts effluent flow and quality next to production and CIP data, so a strength spike can be traced back to its source.
- aQ WaterGuard meters effluent flow and links it to the plant water balance
- Online quality readings and uploaded lab results sit on the same timeline
- Alerts flag load spikes that may point to product loss or a failed rinse recovery
- Records support the plant's own regulatory reporting, which the plant files