Within the frame of examinations with BAK 1095 (small-scale test according to DIN V 54900 part 3 and ”con-trolled composting test ” DIN V 54900-Part 2, No. 3), the following working hypothesis as postulated by J. Fritz (1999) in his PhD-Thesis was tested: the ”negative ecotoxicological impact ” of the biodegradable material BAK 1095, produced by Bayer AG, mainly bases on the emission of heavily toxic NH3. Fritz used the ”controlled composting test” for the production of his compost and reached reproducibly negative results in bioassays (inter alia Daphnia, algae (Scenedesmus sp., Chlorella sp.) and cress) with compost containing 15 to 17 weight % of BAK - polymers.
As a result of the applied method ”controlled composting test”, especially when using base materials with high nitrogen contents, NH3 and immature compost develop. According to Fritz, the compost with BAK showed considerably higher contents of total N, strongly increased pH-values and a higher elutable proportion of organic matter when compared to the control, as well as extremely high NH4-N-contents (55 to 78 times higher than the control without BAK). The working hypothesis could be backed up by our examinations, in pilot-scale tests (PlanCoTec) as well as under the conditions of the controlled composting test (OWS). In both tests, extremely high NH4-N contents were recorded in early stages of the composting of BAK 1095 as com-pared to the control without BAK addition. During the pilot scale composting NH4-N values were reduced by 99 %. In the controlled composting test, however, the NH4-values did not decrease. Thus, toxic impacts measures in bioassays with sensitive testing organisms (cress test for gaseous phytotoxic substances, daphnia ) took a paral-lel course to the ammonium contents. However, these impacts occurred independent from the addition of BAK 1095, when NH4-N levels were artificially raised to the same level as in treatments with BAKs by the addition of ammonium to the control treatments. Tests with test plant barley which is less sensitive against NH4-N/ NH3 showed no negative effects with the same compost. Therefore, it has to be assumed that the results as found by Fritz are mainly, if most probably not entirely caused by a pure NH3-effect. An additional cause is the chosen testing method.
KEYWORDS: BAK 1095, DIN V 54900, controlled composting test, ecotoxicity, Ammonia toxicity
Copyright: | © European Compost Network ECN e.V. |
Quelle: | Wolfsburg 2000 (September 2000) |
Seiten: | 13 |
Preis: | € 6,50 |
Autor: | Dipl.-Ing. Ralf Gottschall Dr. Christian Bruns B. De Wilde |
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© Lexxion Verlagsgesellschaft mbH (8/2024)
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