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Instructions
Calculate Effluent BOD
Read the test procedure or protocol for BOD effluent test used in your laboratory before conducting the test. Adjust the samples as needed following the standard methods for effluent samples that are alkaline, acidic, chlorine concentrated, toxic containing or supersaturated with dissolved oxygen.
Determine the initial (Di) and final (Df) dissolved oxygen measurements using a dissolved oxygen meter. The initial dissolved oxygen should be measured on the sample after the dilution water is prepared from the sample source and any temperature adjustments are made and seed control and nitrification inhibitors are added. In addition, conduct a glucose-glutamic acid check to determine the presence of toxicants, which can alter results. Place the sample in an incubator as indicated and measure the final dissolved oxygen.
Determine the BOD of the seeding material. Divide the dissolved oxygen depletion by the volume of seed in milliliters for each seed control bottle exhibiting 2.0 milligrams per Liter depletion and greater than 1.0 mg/L minimum residual dissolved oxygen. Average the results. This calculation will be represented as an S, oxygen uptake of seed.
Calculate the BOD for each test bottle exhibiting 2.0 mg/L minimum dissolved oxygen depletion and at least 1.0 mg/L residual dissolved oxygen. BOD equals the final dissolved oxygen (Df) subtracted by the initial dissolved oxygen (Di) subtracted by the oxygen uptake of seed (S) multiplied by the volume of seed suspension in the test bottle (Vs) and divided by the dilution factor (P). P is the decimal volumetric fraction of sample used (1/P). The written formula for the BOD calculation is BOD=(Di-Df) - (S)(Vs)/P.
Average the BOD results for all test bottles. Compare results with standard effluent BOD concentrations. Conduct statistical analyses, such as Student t-test, to find any significant difference between your results and the standard.