Abstract
Proper assessment of biodegradable materials depends on the wide adoption of standard test methods. Although such methods exist, testing capacity remains limited, constrained by cost and the start-up time to establish new laboratories. This modified screening protocol is based on the ASTM International D6691-24a, Standard Test Method for Determining Aerobic Biodegradation of Plastic Materials in the Marine Environment by a Defined Microbial Consortium or Natural Sea Water Inoculum. It assesses the biodegradation of materials in a marine environment, comparing results to positive and negative controls, and uses a natural seawater inoculum supplemented with ammonium and phosphate to prevent nutrient limitation. Materials are exposed to this nutrient-enriched seawater and incubated at 30 degrees C. A Micro-Oxymax respirometer measures the production of biogas (carbon dioxide, CO2) over time. The degree of mineralization (biodegradation) is determined by calculating the proportion of material-derived carbon converted to biogas-carbon. The percent CO2 production, expressed as a fraction of the measured or theoretical carbon content, is reported as a function of time. The closed-loop respirometry system accommodates a range of reactor vessels, prepared in triplicate for each material, a negative control (seawater inoculum only), and a positive control (thin-layer chromatography cellulose). This method is important for evaluating materials in the marine environment and addresses global pollution prevention.