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A Simplified Headspace Biochemical Oxygen Demand Test Protocol Based on Oxygen Measurements Using a Fiber Optic Probe
Author(s) -
Min Booki,
Kohler David,
Logan Bruce
Publication year - 2004
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143004x141555
Subject(s) - biochemical oxygen demand , chemical oxygen demand , oxygen , clarifier , wastewater , effluent , chemistry , limiting oxygen concentration , environmental science , environmental engineering , organic chemistry
Batch respirometric tests have many advantages over the conventional biochemical oxygen demand (BOD) method for analysis of wastewaters, including the use of nondiluted samples, a more rapid exertion of oxygen demand, and reduced sample preparation time. The headspace biochemical oxygen demand (HBOD) test can be used to obtain oxygen demands in 2 or 3 days that can predict 5–day biochemical oxygen demand (BOD 5 ) results. The main disadvantage of the HBOD and other respirometric tests has been the lack of a simple and direct method to measure oxygen concentrations in the gas phase. The recent commercial production of a new type of fiber optic oxygen probe, however, provides a method to eliminate this disadvantage. This fiber optic probe, referred to here as the HBOD probe , was tested to see if it could be used in HBOD tests. Gas–phase oxygen measurements made with the HBOD probe took only a few seconds and were not significantly different from those made using a gas chromatograph ( t test; n 5 15, R 2 5 0.9995, p , 0.001). In field tests using the HBOD probe procedure, the probe greatly reduced sample analysis time compared with previous HBOD and BOD protocols and produced more precise results than the BOD test for wastewater samples from two treatment plants (University Area Joint Authority [UAJA] Wastewater Treatment Plant in University Park, Pennsylvania, and The Pennsylvania State University [PSU] Wastewater Treatment Plant in University Park). Headspace biochemical oxygen demand measurements on UAJA primary clarifier effluent were 59.9 ± 2.4% after 2 days (HBOD 2 ) and 73.0 ± 3.1% after 3 days (HBOD 3 ) of BOD 5 values, indicating that BOD 5 values could be predicted by multiplying HBOD 2 values by 1.67 ± 0.07 or HBOD 3 by 1.37 ± 0.06. Similarly, tests using PSU wastewater samples could be used to provide BOD 5 estimates by multiplying the HBOD 2 by 1.24 ± 0.04 or by multiplying the HBOD 3 by 0.97 ± 0.03. These results indicate that the HBOD fiber optic probe can be used to obtain reliable oxygen demands in batch respirometric tests such as the HBOD test.