Zahn-Wellens test

Figure 10.18 DOC-elimination rate curves for poly(vinyl alcohol) with optimally adapted and non-adapted inoculum according to the Zahn-Wellens test [212]... 

OECD Guideline for testing of chemicals, Inherent biodegradability modified Zahn-Wellens-test 302B cited in Ref [300, 300a]... 

Figure 9.6 Biodegradability of structurally related antineoplastics [113] (CBT— closed bottle test ZWT = Zahn-Wellens test).

DIN EN 29 888 (1993) Verfahren zur Bestimmung der inharenten biologischen Abbaubarkeit von Ab-wasserinhallssloffen und Chemikalien (Zahn-Wellens-Test). 

The results of the wet oxidation of the model substances were transfered to waste water from the pharmaceutical industry. The non-degradable compounds were converted into harmless substances which can be decomposed biologically. This results were confirmed by a Zahn-Wellens-test. The combination of wet-oxidation and following biological treatment allows a TOC reduction of more than 90%. 

The inherent biodegradability tests concerned are the Zahn Wellens test (OECD TG 302 B) and the MITIII test (OECD TG 302 C). The conditions for use in this regard are ... 

EC C.9. Biodegradation Zahn-Wellens test. Directive 67/548/EEC, Annex V. (1988)... 

Furthermore, the inhibition rate of activated sludge samples were determined and a Zahn-Wellens test carried out to assess the potential for removal of the dyes entering the biological stage of a wastewater treatment plant. Dyes were tested up to a concentration of 100 mg r (the EC cut-off limit for classification and labelling). The ecotoxicological profile can be summarized as follows ... 

Fig. 2.7-5 Example of a Zahn-Wellens test ofwastewater containing acetic acid. The plot shows the relative decrease in DOC.

A considerable number of standardized OECD and International Organization for Standardization (ISO) methods for measuring the biodegradability of surfactants are available. Table 22.4 gives an overview of such methods. ISO 7827 and OECD 301 A are used to determine the ultimate biodegradability in the aquatic environment. This is achieved via the measurement of dissolved organic carbon (DOC) at an incubation period of 28 days. The widely used Zahn-Wellens Test (OECD 302 B) is also a static method but works with a substantially higher biomass and substrate concentration (50-400 mg/1). This corresponds more to the situation in a real waste-water treatment plant. 

DOC removal in 28 d OECD 302B, Zahn-Wellens test 16... 

Figure 7.1 Top ifosfamide (left) and p-D-Clc-IPM (INN glufosfamid right). Bottom biodegradability of structurally related cytotoxics (top from left to right 5-fluorouracil (5-FU), gemcitabine and qftarabine) in different OECD tests for the assessment of biodegradability (CBT closed bottle test, OECD 301D ZWT Zahn-Wellens test, OECD 302B).

Zahn-Wellens test OECD 302B [27] and ISO 9888 [28]. Monitoring of decrease of COD or DOC. 

Environmental 40 - 80 % biological degradability (Zahn-Wellens test) EC50 (daph-nia magna) 220-520 mg/l considered to be a weak water pollutant (German law) do not allow to enter soil, watenways or waste water canal. 

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