Biodegradation curves

CO2, a blank compost inoculum without an additional carbon source (polymer sample) is simultaneously tested under the same conditions. The CO2 content of the exhaust air of both vessels is compared. After subtracting the CO2 evolution of the blank inoculum, the CO2 evolution related to the test polymer is monitored and plotted as a biodegradation curve (see Fig. 1). Finally, the activity of the compost inoculum in the controlled composting test is validated using a cellulose reference instead of the polymer. In Fig. 1, the biodegradation curve of Ecoflex is depicted. After 80 days, 90% of the theoretical CO2 evolution is reached. Thus, Ecoflex is ultimately biodegradable according to the ISO standard for compostable polymers (ISO 17088), which requires 90% of the theoretical CO2 evolution within 180 days. 

Figure 14.9. Example of typical biodegradation curve (the first part of the curve resembles the Hill sigmoid)...

Figure 4. Biodegradation curves of C and D hot pressed PVA based films under simulated soil burial conditions, compared with the mineralization profile of D blend diminished of the PVAc-derived organic carbon.

Figure 5. Biodegradation curves of atactic PHB and PVA samples and their graft copolymers and blends in an aqueous medium in the presence of PVA-degrading microorganisms.

Albertsson AC. The shape of the biodegradation curve for low and high density polyethenes in prolonged series of experiments. Eur Polym J 1980 16 623-630. 

The level of biodegradation is determined by comparing the BOD with the theoretical amount (ThOD) and expressed in per cent. The influence of possible nitrification processes on the BOD has to be considered. The test result is the maximum level of biodegradation determined from the plateau phase of the biodegradation curve. There is the possibility of improving the evaluation of biodegradability by calculating a carbon balance. 

Figure 6-11 Biodegradation curves of a PVA-based film and filter paper recorded in simulated soil burial respirometric tests. Reprinted with permission from [116],...

Figure 5.4 shows an example of a CO2 biodegradation curve of the blank compost inoculum and the cellulose positive reference, each of 3 replicates. From the difference in CO2, the net biodegradation can be calculated and graphically represented as in Figure 5.5. 

Adamo AM, Giovannotti M, Magaudda G, Plossi Zappala M, Rocchetti F, Rossi G (1998) Effect of gamma rays on pure cellulose paper. Restaurator 19 41-59 Albertsson A-C (1980) The shape of the biodegradation curve for low and high density polyethylenes in prolonged series of experiments. Eur Polym... 

Kinetics of Pesticide Biodegradation. Rates of pesticide biodegradation are important because they dictate the potential for carryover between growing seasons, contamination of surface and groundwaters, bio accumulation in macrobiota, and losses of efficacy. Pesticides are typically considered to be biodegraded via first-order kinetics, where the rate is proportional to the concentration. Figure 2 shows a typical first-order dissipation curve. 

Reaction rate limited (zero-order kinetics). In this case, the biofilm concentration has no effect on reaction rate, and the biodegradation breakthrough curve is linear. 

Figure 10.17 Biodegradation rate curves for poly(vinyl alcohol) with adapted and non-adapted inoculum according to the Sapromat test [212]...

The determination of the COD components depends on the fact that the substrate uptake can be experimentally related to the OUR curve. The heterotrophic yield constant, YHw, that is experimentally determined from procedure number 1, Section 7.2.1, relates the oxygen uptake to the readily biodegradable substrate that is consumed irrespective of its origin, being either directly available or continuously produced from hydrolyzable COD fractions. 

An ROC curve plots the true positives against the false positives for different classifications of the same set of objects this corresponds to plotting a against n - a using the notation of Table 1, and thus the shape of an ROC curve tends to the shape of a cumulative recall plot when n a. An example of the use of ROC plots in chemoinformatics is provided by the work of Cuissart et al. on similarity-based methods for the prediction of biodegradability (24). 

For example, Schmidt et al. (1985) developed 12 kinetic models for the metabolism of organic chemicals that are not supporting bacterial growth. Assignment of the appropriate kinetic model requires measurement of sufficient experimental points on the disappearance curve. Often insufficient data points are collected to assign a kinetic model, especially with screening studies. Temperature definitely has an impact on the biodegradation kinet- 2000 CRC Press LLC... 

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