CARLOS JAVIERRE, JUDITH SARASA, ISABEL CLAVERIA, ANGEL FERNANDEZ STUDY OF THE BIODISINTEGRATION ON A PAINTED BIOPLASTIC MATERIAL WASTE The influence of the painting process on a biocompostable waste is studied. Disintegration degree (D %) of a 100% biocompostable plastic made from potato almidon is calculated for both painted and non -painted samples. Solid matrix is also characterized by means of a laboratory scaled composting process following UNE-EN norms <2, 3>. It can be concluded that painting has a negative influence on biocomposting process decreasing 4.48% disintegration degree. Average D% for painted samples is 84.56 %, and 89.04 for non- painted ones. Regarding to solid matrix, dry mass after composting is double (91.12 %) as before process (43.63 %) for painted samples and 91 % and 45.41 % after and before composting for non-painted samples. Volatile solids are reduced 5.17 % after composting for painted samples, and 8.78 % for non-painted. Organic nitrogen is reduced 0.34 % and 0.16% for painted and non-painted samples respectively. The negative effect of painting is mainly due to the barrier effect of the paint that prevents microorganisms from converting organic components of the biopolymer into water, CO2 and compost.