Conference paper
Improvement of the method for the determination of bod in highly polluted waters
N. Šoštarić
; Hidrometeorološki zavod SR Hrvatske, Zagreb
Abstract
The experience with the determination of the biochemical oxygen demand (BOD) has shown the following: 1. In a prepared sample of water put into several flasks an appreciable deviation in the BOD5 values was found. 2. If the ratio of dissolved oxygen to BOD5 in the flask is changed, the BOD5 value also changes. 3. The BOD5 of the water used for dilution, changes the BOD5 value of the sample. A deviation of ± 10% from the average BOD5 value can be considered satisfactory. The deviation is due to the roughness of the inside surface of the flask and to the possible presence of microelements on the surface which inhibit or stimulate microbiological processes. It is therefore necessary to maintain the same ratio of 02 to BOD5 in order to obtain the best possible interpretation. The indicator of the relatively exact dilution is the amount of KMnO4 used and the ratio of KMnO4 to BOD5. From experience the ratio 02 to BOD5 should be 1.5 ± 12%, i. e. 1.34 to 1.68. The greater the dilution of the original sample, the stronger the influence of the BOD value of the water used for dilution. This must be taken into consideration when making calculations.
Keywords
Hrčak ID:
167786
URI
Publication date:
5.9.1974.
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