Accelerating polymer biodegradation through the use of pre-adapted sludge in an OECD 302B inherent biodegradability...

There has been an increased focus on the environmental fate of polymers in recent years. However, existing test methods and guidelines for biodegradation, which is a critical element defining the environmental fate of substances, may not be suitable for polymers due to the complex and challenging nature of assessing polymer biodegradation. Specifically, accelerated biodegradation test methods are needed considering that polymers generally require longer durations for biodegradation to occur. The use of a pre-adapted inoculum derived from activated sludge is one approach that has been examined to shorten study duration and provide more realistic information on polymer fate behavior in the environment. This paper evaluates the impact of pre-adaptation on the biodegradation of six polymeric materials covering four different polymer chemistries in an OECD 302B test. No difference in biodegradation results was observed between the pre-adapted and non-adapted treatments for five of the materials (a low substitution methyl hydroxyethyl cellulose, a high substitution methyl hydroxyethyl cellulose, a cationic dextran, a high molecular weight poly(ethylene oxide), and a low substitution hydroxypropyl methylcellulose). For the remaining material (high substitution hydroxypropyl methylcellulose), the use of pre-adapted sludge resulted in faster degradation kinetics. The results presented here demonstrate that the use of pre-adapted inocula in an OECD 302B study has the potential to shorten study durations while not significantly changing the ultimate assessment of biodegradability of the material.