A Need to Explain Apparent ‘Hard-to-biodegrade’ Cellulose Remainders in CO2-based Test Results

Abstract

The extent of cellulose fiber biodegradation, according to many published studies, tends to reach a plateau value well below 100%. This editorial proposes that the apparent residue of not-biodegraded cellulose may be due to simplifying assumptions in a commonly used assay to quantify cellulose biodegradation. Some such tests are based on the production of CO₂. The evolved CO₂ is removed from the air by an alkaline trap, which triggers a quantified addition of O₂ gas. However, N₂ and NH₃ gases are evolved during biodegradation. The theoretical amount of nitrogen might explain a shift of up to 0.63% in the extent of biodegradation. Another possibility is that the evolution of nitrogen-based gases starves the biological system of nitrogen, thereby terminating biodegradation in the test container. This editorial asks: “Is biodegradation of cellulose usually more complete in comparison to the results from standard tests?” If yes, that would match the fact that cellulose does not build up endlessly in the environment. These findings have direct implications for natural fibers such as cotton, which might be systematically underdetermined in standard biodegradation comparisons against synthetic fibers.