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Biochemical Oxygen Demand (BOD) is the amount ofoxygen, expressed in mg/L or parts per million (ppm), that bacteria take from water when they oxidize organic matter. The carbohydrates (cellulose, starch, sugars), proteins, petroleum hydrocarbons and other materials that comprise organic matter get into water from natural sources and from pollution. They may be dissolved, like sugar, or suspended as particulate matter, like solids in sewage.Organic matter can be oxidized (combined with oxygen)by burning, by being digested in the bodies of animals and human beings, or by biochemical action of bacteria....

The format of the APHA BOD test (dilution method) as itis ordinarily arranged is complex and carrying out the tests requires a great deal of time. The usual approach also has several inherent weaknesses, which cause numerous operating troubles.To simplify the procedure and save time withoutchanging the standard test, it has been possible to rearrange the format of the system and to package reagents in sterile pillows.Ӕ Stable PAO (phenylarsine oxide) solution or stabilized thiosulfate also can be substituted for unstable thiosulfate used in the dissolved oxygen (DO) determination. These changes...

Seeding Dilution Water Using seeded dilution water is not necessary when measuring the BOD of sewage, sewage plant effluent (unless it has been chlorinated) or river water. However, some samples do not contain sufficient bacteria to oxidize any organic matter that may be present. Many industrial or trade wastes are of this type. Also, many sewage treatment plants chlorinate their final effluent so that it is essentially sterile and thus impossible to test directly for BOD. In order to test such samples, it is necessary to seed theprepared BOD dilution water. This is done by adding a small measured...

Figure 3 Summary Numerous advantages are gained by graphing the amount of DO remaining versus the mL of sample. Bad data points are evident and can be judged as outliers and dropped. In contrast to the APHA method where only one point is used and its validity is not known, the graphical method determines BOD of the sample from all valid points. In addition, because calculating or measuring the initial DO for each dilution is no longer necessary, extra work and possible errors are eliminated. If the dilution water used a demand (from a blank or seeding), it is incorporated into the graph automatically...

MeanStandardfive-day BODDeviationType of Seedmg/Lmg/L Settled fresh sewage21811 Settled stale sewage207ѱ8 River water (four sources)224-2427-13 Activated sludge effluent221ѱ13 Trickling filter effluent2258 7 6 5 4 3 > mg/L DO Remaining 2 > Note: Data taken from Standard Methods , 14th ed., p. 548, 1975. Because the BOD standard prepared by Hach contains300 mg/L each of glucose and glutamic acid, the BOD value determined from the graph must be divided by two to be compared with values in the table. DO RemainingBOD StandardAfter 5 Days 1 Example of a Calculation A series of four BOD bottles was...

Optional Reagents and Apparatus 14865-10BOD Standard, 10-mL Voluette Ampules16 621-00Bottle, glass-stoppered, BOD, 300 mL6 620-11Bottle, poly, wash, 500 mLeach 14868-17Bottle, aspirator, poly, 4 L, with spigoteach 14868-58Bottle, aspirator, poly, 10 L, with spigoteach 431-53Buffer Solution, phosphate, pH 7.2, APHA1 L 681-40Buret, Teflon stopcock, 25 mLeach 428-53Calcium Chloride Solution, APHA1 L 459-01Cap, dispenser, for Nitrification Inhibitoreach 2419-06Cap, for BOD bottle6 968-00Clippers, for opening pillowseach 508-42Cylinder, graduated, 100 mLeach 429-53Ferric Chloride Solution1 L 505-46Flask,...

1. Minimal sample preparation time is required. > A measured sample of sewage or wastewater is placed in one of the amber bottles on the apparatus and the bottle is connected the instrument. Above the sewage or water sample is a quantity of air, which contains 21 percent oxygen. Over a period of time, bacteria in the sewage consume dissolved oxygen to oxidize organic matter present in the sample. The air in the closed sample bottle replenishes the used oxygen, resulting in a drop in air pressure in the sample bottle. The BODTrak Apparatus measures the drop in pressure and displays results directly...

BODCurves Figure 7 shows some examples of BOD curves that might be found. 1. Carefully follow the complete directions for initialsetup that came with your instrument. 2. Heat or cool a sample volume (e.g., 420 mL for 0 to35mg/L range) to within 2 C of its incubation temperature, typically 20 аC (68 F). 3. Using a clean graduated cylinder, pour the requiredsample volume into a clean sample bottle. > KA N 4. Place a 3.8-cm (1-1/2-inch) magnetic stirring bar ineach sample bottle (included with the apparatus). > AHB 5. Add the contents of one BOD Nutrient Buffer Pillowto each bottle for optimum bacterial...

Optional Reagents and Apparatus 14866-10BOD Standard, 10-mL Voluette Ampules16 14868-17Bottle, aspirator, poly, 4 L, with spigoteach 459-01Cap, dispenser, for Nitrification Inhibitoreach 508-40Cylinder, graduated, 25 mLeach 508-46Cylinder, graduated, 250 mLeach 508-49Cylinder, graduated, 500 mLeach 2533-35Nitrification Inhibitor35 g 20934-38Pipet, Mohr, 10.00 mLeach 24712-00Polyseed REAGENTS AND APPARATUS FOR THE MANOMETRIC METHOD Cat. No.DescriptionUnit 14160-66BOD Nutrient Buffer Pillow makes 300 mL of dilution water50 14861-98BOD Nutrient Buffer Pillow makes 3 L of dilution water25 14862-98BOD...

Azide Modification of Winkler Method APHA Standard Methods , 16th edition, 418 (1985)Introduction The dissolved oxygen test is one of the most important analyses in determining the quality of natural waters. The effect of oxidation wastes on streams, the suitability of water for fish and other organisms, and the progress of self-purification can all be measured or estimated from the dissolved oxygen content. In aerobic sewage treatment units, the minimum objectionable odor potential, maximum treatment efficiency, and stabilization of wastewater depend on maintaining adequate dissolved oxygen....