Water test reports are a regular part of environmental compliance, but the parameters on them are rarely explained. Here is what the most common ones mean.
pH
pH shows how acidic or alkaline the water is. Dyeing and washing processes can swing it sharply in either direction. Treated effluent needs to stay within a neutral band; a reading outside it usually points to a problem with chemical dosing or equalization.
BOD — Biochemical Oxygen Demand
BOD measures how much oxygen bacteria need to break down the organic matter in the water. A high BOD means the effluent would starve a river of oxygen. In an ETP or STP, the biological stage is responsible for bringing BOD down.
COD — Chemical Oxygen Demand
COD measures the oxygen needed to oxidise everything in the water chemically, including substances bacteria cannot easily digest. COD is always higher than BOD; a large gap between them suggests hard-to-treat chemicals.
TSS — Total Suspended Solids
TSS is the amount of solid particles floating in the water. High TSS usually means the clarifier or filters are not working well, or that sludge is not being removed often enough.
Other parameters you may see
- Dissolved oxygen (DO) in the aeration tank
- Total dissolved solids (TDS) and electrical conductivity
- Colour, oil and grease, and heavy metals for specific industries
Getting reliable results
Samples must be collected correctly, preserved and delivered to the laboratory quickly. We arrange sampling and testing for ETPs and STPs and deliver your report on time for DOE submissions.
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