Biodegradable and home compostable materials

Microbial bio-polyesters produced from agricultural and agro-food residues

Polyhydroxy(butyrate-co-valerate), P(HB-co-HV) produced from (non-food) feedstocks, using eco-efficient up-scaled conversion process, would permit to endow the packaging industry with “bio-benign” (no risk of microplastics pollution) biodegradable and home compostable materials.

These biopolymers are completely biodegredable to water and carbon dioxide at room temperature and therefore considered amongt the most promising alternatives of oil-based synthetic polymers to tackle current negative externalities of our plastic packaging.

Polyhydroxy(butyrate-co-valerate), P(HB-co-HV) production

Two different agro-food residues were chosen, used in the two different pilot plants of the project.

• The pilot scale biorefinery, located in Isola della Scala in Italy investigated the PHA production by the biological conversion of VFAs obtained by the acidogenic fermentation of corncob products as valuable raw material. This pilot plant can produce around 500 g of PHA every day, but the recovery capacity is still the bottleneck when operating in real environment. The actual quantity of PHA recovered and extracted after production was around 1 kg any two weeks.

• The pilot scale Plant located in iBET, Lisbon (Portugal) investigated PHA production by the conversion of fruit waste to VFAs through acidogenic fermentation and in a Upflow Anaerobic Sludge Blanket (UASB) reactor. Under optimal conditions, this pilot plant is able to produce around 3Kg of PHA per month under the optimum conditions

Strategies were developed for bioplastic production to enable a new biobased market soon in the future by replacing conventional plastic production coming from fossil-based raw materials.

Polyhydroxy(butyrate-co-valerate), P(HB-co-HV) processing

Production strategies were established for flexible films, one thermoformed tray, and one injection-molded cup, tailored to fulfil the requirements of the targeted foods.

Thermoplastic processing of PHA raw materials started with with compounding the PHBV powder into pellets followed by injection-moulding into cups or extrusion into flexible films followed by thermorforming into trays. After each processing step characterization of different properties was carried out like thermal or mechanical properties.

Cups of PHBV were successfully produced by injection molding with automatic cycling using different commercial grades of PHBV. More than 1500 cups were injection moulded and used during the shelf-life tests of fresh cheese provided by Soredab. Flat film extrusions were successful for thick films followed by thermoforming process into trays. More than 150 thermoformed trays were produced for further shelf-life testing.

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