BIODEG, Lab device for assessing the ultimate aerobic biodegradability of plastic polymers, according to the EN ISO 14855-1 standard

An experimental Lab device compliant with the standard UNI EN 13432 and ISO 14855-1 has been designed and set-up at ISAFOM-CNR, Perugia.Developed within the framework of ECO-POT project, the equipment is used to study the ultimate biodegradability of different bio-polymers exploited for making biodegradable pots used for plant nursery.Designed to estimate the degree and rate of aerobic biodegradation of polymers on exposure to a controlled-composting environment under laboratory conditions, the machinery automatically measures the evolved carbon dioxide emission by IRGA over a period up to 6 months. Test specimens are exposed to an inoculum that is derived from compost from olive mill waste. The multiunit performs sequential analysis on exhausted air coming from different samples run in triplicates (up to 12 bio-reactors) by selecting the mass flow escaping from each bioreactor (vessel) and switching the air-manifold. The apparatus keeps under automatic control pressure of the inlet air, temperatures, CO2 concentration and flow rate of the exhausted air, by a custom LabVIEWTM program, interfaced with a data acquisition system. To ensure optimal and homogeneous microbial activity all along the test, vessels are weekly shaken while the humidity of the inoculum is maintained around 50%. Acquisition of signals, control of actuators, remote software supervision, data elaboration and monitoring are performed by means of fit-for-purpose integration of hardware and software. Parameters under control are recorded, plotted and promptly displayed in tables, graphs and spreadsheets, clearly showing in real time the degree and rate of biodegradation of each sample under analyses. Findings (biodegradation curves) showed that some of the tested samples reached a degree of biodegradation > 80% in a very short time (less than 20 days). CO2 emissions (mass balance), recorded and calculated by the multiunit here described, has been validated simultaneously to the IRGA analyses by using the titration method carried out on the exhausted air trapped in BaOH solution and outgoing from vessels randomly chosen.