The use of Spectroquant Merck BOD photometric test to evaluate the stabilityof organic matters in soil

Abstract

We proposed a new method to determine the rate constant of biochemical oxidation of soil organic ma�ers that makes it possible to evaluate their stability by Spectroquant Merck BOD photometric tests; if smaller samplings are used and individual determinations are performed, it can replace the method of BOD vacuum measuring by an Oxi Top Control Merck system. The time and labour consumption of this vacuum method is sometimes criticised, but it has demonstrable work advantages for a large series of samples and so it is still recommended. The two methods are identical as for the correctness and coincidence of results and they do not differ by either lower or higher results and therefore we recommend the new method with photometric tests for smaller series of samples. For the high time and labour consumption we must warn against the use of traditional BOD dilution method with volumetric determination of oxygen for the determination of rate constants. MATERIAL AND METHODSTwo collection-testing samples of soils were used for the determinations: one sample with a higher content of organic matters, the other with a lower content and higher stability of these matters. These two different samples were analysed by a newly proposed method of photometric tests Spectroquant Merck BOD KT with the range of 0.5-3000 mg O 2 /l (cat. no. 100687) that is based on a modification of the traditional Winkler's method. We employed BOD standard for the preparation of 10 l of standard solution (cat. no. 100718) and BOD nutrient mixture with allylthiourea for 12 l of nutrient solution (cat. no. 100688). For each determination at least 4 oxygen reaction vessels for BOD determination (cat. no. 114663) were necessary. CHOD test with the range of 10-150 or 15-300 mg O 2 /l (cat. nos. 114540 and 114895) was used to determine the total amount of organic matters. These are cuvette, not reagent tests.Measurements were carried out in a Spectroquant NOVA 60 photometer that works with 12 filters by the diode field technique (reference ray technique), is connected to a PC with the software Windows Multi Achat II for data processing and has the memory capacity for 1000 data blocks. It has an Auto Select function for differentiation of tests according to the bar code and AQA (Analytical Quality Assurance) function.The two tested samples of the soils were analysed by the previously described method OXI Top Control WTW Merck .The procedure of sample preparation and the conduct of the cultivation process were the same as described in the cited paper. Because the photometric measurements are not accessible if the sample turns turbid, just before the photometric measurement the sample was drawn with a syringe and before the transfer into the cuvette of the apparatus it was filtered under an N 2 screen using an Anotop MERCK membrane filter of porosity 0.45 µm directly onto the perpendicularly upwards set syringe until air bubbles were removed from the filter. The spectrophotometer has a built-in function of "turbidity correction".The correctness of t...

BOD & COD reduction from textile wastewater using bio-augmented HDPE carriers

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Influence of the degree of soil organic matter lability on the calcium carbonate equilibrium of soil water

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Utilisation of Waste from Digesters for Biogas Production

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