Abstract
Long-term incubations of biochemical oxygen demand (BOD) were performed to determine the aeration coefficient derived from oxygen uptake experiments. The BOD bottles were prepared with distilled water and the incubation occurred in the dark, under controlled temperature (19.4ºC). The bottles were submitted to two different treatments based on the initial dissolved oxygen (DO) concentrations (Treatment 1: 1.43mg L-1 and Treatment 2: 7.67mg L-1). The DO concentrations were measured with an OD meter during 52 days. The results were fitted to a first-order kinetics model. The BOD bottles showed an increase in DO concentration for both treatments and the mean aeration coefficient (ka) was 0.065 a day-1. The fittings pointed to some dispersion in the ka values, and the initial concentration of DO in the BOD bottles does not interfere in the aeration process, being a random process
Highlights
Biodegradation is an important mechanism in the organic matter removal in natural systems
The aeration process is intrinsic to the method of measuring dissolved oxygen concentrations in long-term aerobic mineralization experiments; with this respect, this study aims at determining ka and discussing the effect of DO initial concentration in the samples
The caution in asepsis of the oxygen electrode was warranted. This kind of interference is inherent in long-term Biochemical oxygen demand (BOD) experiments; they usually last an average of 45 days, and the samples are submitted to a large number of measurements
Summary
Biodegradation is an important mechanism in the organic matter removal in natural systems. Biochemical oxygen demand (BOD) is a widely used parameter for the determination of biodegradable organic compounds in aquatic systems, effluents and wastewater (Matos and Sousa, 1996; Hu et al, 1999; Orupõld et al, 1999). During aerobic degradation microorganisms oxidize organic matter in the presence of oxygen; as a result, dissolved oxygen (DO) is consumed by this oxidation. In 1925 Streeter and Phelps formulated a model that evaluated the BOD budget in aquatic systems. The biological oxygen depletion was directly related with oxidation of the organic substrate by microbial communities under aerobic conditions (Henze et al, 1997; Gotvajn and Zagorc-Koncan, 1999). The development of easy-to-use methods for practical applications is important for the mathematical modeling of ecological processes, which have
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