Wet chemistry test results provide needed insight into water quality. Many of the analyses performed in the “wet lab” are basic chemistry methods. Some are as simple as measuring pH. All the methods involve gravimetric, titrimetric or electrochemical techniques. Although basic in nature, most of the equipment utilizes computer systems to accurately and efficiently analyze samples. These measurements provide important environmental data; measurements that are fundamental in decision making for wastewater, effluents, and polluted waters.
The Wet Laboratory Section is equipped with pH and conductivity meters, balances, spectrophotometers, and Lachat colormetric analyzer.
- Lachat Colormetric Analyzer
- Uses color changes in the sample to determine the concentration of each nutrient.
- Each sample is mixed with a combination of reagents that form a specific colored compound for each nutrient.
- The color's intensity correlates to the amount of nutrient present.
- Ion Chromatograph
- The ion chromatograph separates by chromatography each analyte so they can be detected individually.
- The detector identies each analyte based on retention time.
- BOD (Biological Oxygen Demand)
- The initial dissolved oxygen of the water sample is measured and recorded.
- The sample is kept warm at a controlled temperature for five days.
- The final dissolved oxygen is measured and then interpreted as a representation of biological activity due to the loss of oxygen.
- COD (Chemical Oxygen Demand)
- The sample is digested and refluxed in a strong acidic solution with potassium dichromate.
- The oxygen consumed is measured against standards at with a spectrophotometer.
- The resultant measures indicates the amount of oxidizable organic mattter.
- TSS/NFR (Total Suspended Solids/Non-filterable Residue)
- Samples are filtered through a previously weighed 0.45 micron filter.
- After drying, the filter is weighed again. The test result is the weight of the filtered material.
- VSS (Volatile Suspended Solids)
- The filter and reisdue from a TSS/NFR is further dried at 500 degrees centigrade.
- The resultant volatile residue driven off is the VSS test result.
- TDS (Total Dissolved Solids)
- Similiar to TSS/NFR except a 2 micron filter is used