What is the difference between bod5 and cbod5

Factors affecting the ammonia-related BOD concentration in Reach 2 include the quantity of organic nitrogen algae contributed from Reach 1, the ammonification rate in Reach 2, the residence time in Reach 2, the efficiency of the Stockton RWCF treatment system in removing ammonia, and the river flows. Increased algal loads into Reach 2 from Reach 1 increase the potential quantity of ammonia-related BOD in Reach 2 that could be derived via ammonification. Another factor affecting ammonia-related BOD concentrations is the ammonification rate in Reach 2, which is slow and prevents a portion of the organic nitrogen inputs from Reach 1 from being converted to dissolved ammonia in Reach 2 Lehman This ammonification rate depends on water temperatures, which could therefore indirectly affect the ammonia-related BOD concentrations.

Average monthly ammonia as nitrogen concentrations in the RWCF effluent ranged from 1. It should be noted that the 5-day NBOD is only a portion of the total nitrification demand for oxygen.

Reach 1 inflows are another source of ammonia to Reach 2. The ammonia concentrations from Reach 1 less than 0. River flows can affect ammonia-related BOD concentrations by affecting the Reach 1 organic nitrogen inputs and the amount of time available for ammonification to occur in Reach 2 and by diluting dissolved ammonia loads from the Stockton RWCF.

These measurements suggest that ammonia may be a less significant contributor to BOD concentrations in Reach 2 than algal inputs. The high ammonia concentration discharged by the RWCF suggests that ammonia concentrations in Reach 2 may be an important contributor to the BOD concentrations in that reach during the winter.

Ambient air temperature, temperature of water entering Reach 2, and residence time are the primary factors affecting water temperature.

Based on the seasonal temperatures, BOD decay processes are highest in summer and lowest in winter in Reach 2 Brown The literature does not describe the importance of water temperature on the BOD concentrations in Reach 2 or compare the importance of temperature to other factors affecting BOD concentrations. Consequently, millions of dollars may have been spent needlessly on new treatment facilities. The total BOD of a wastewater is composed of two components — a carbonaceous oxygen demand and a nitrogenous oxygen demand.

Traditionally, because of the slow growth rates of those organisms that exert the nitrogenous demand, it has been assumed that no nitrogenous demand is exerted during the 5-day BOD5 test. Although, such assumption is valid when the test is performed on untreated municipal wastewaters, it is not valid when performed on secondary effluents, especially those from aerated lagoons. The BOD5 of effluents from the latter are almost always inflated by a nitrogenous component.

Moreover, unlike the carbonaceous demand which is proportional to the concentration of the biodegradable carbon constituents in the effluent, the nitrogenous demand exerted during the 5-day test is proportional to the number of nitrifying organisms that happen to be caught in the sample being tested.

Thus the argument that the test provides insight on the impact that the effluent will have on the receiving water can not be defended. Neither can the practice of making waste-load allocations from models that contain both a BOD5 assumed to be a measure of the carbonaceous demand and a nitrogenous demand. The severity of the problem is illustrated in Figs. Figure 2 compares the two parameters in filtered samples.

Note should taken of the magnitude of the nitrification factor in the 5-day test. Similar magnitudes are observed in effluents from aerated lagoons in warmer climates.

Figure 1 click on graph to enlarge. Taken from Rich Figure 2 click on graph to enlarge. Such nitrification can be eliminated by the use of commercially available nitrification inhibitors, a practice recommended by Standard Methods Since 1 mole of Nitrogen weighs 14 amu and 1 mole of oxygen weighs 2.

So… why is this important? We have to remember that our dilution water contains ammonia!! NH 3 -N in dilution water can contribute up to 1. Thus a mL sample yields 1. Some have stated that, "no scientific tests have shown any evidence of toxicity when TCMP is used properly", yet Standard Methods recommends that all inhibited samples be seeded to reduce the possibility of interference.

Call us non-believers, but the likelihood of a toxin that affects only a SINGLE species of bacteria seems a little "out there". Calling on science, chemists at the State Lab of Hygiene prepared several replicates of GGA to which inhibitor was added. These replicates were prepared with varying seed volumes, up to three times the typical volume of seed used. The results of this experiment are shown below.