The technology for producing Minerv-PHATM features successive sub-processes that transform the carbon sources contained in agricultural co-products into polyhydroxyalkanoates (PHA), whose properties enable them to replace many oil-based plastics at commercial level, with the added benefit of being biodegradable.
Polyhydroxyalkanoates (PHA) are biodegradable in compost, like other bioplastics, but also in free water, a unique property thanks to the metabolic activity of microorganisms naturally present in the environment.
The Bio-on technology was designed to respect and enhance the eco and bio character of polyhydroxyalkanoates (PHA).
There are two platform products:
The two platform products have considerably different characteristics, enabling different types of non-biodegradable, conventional plastics to be replaced.
Indeed, PHBVV is a family of molecules the flexible nature of which enables it to be modulated according to the needs of the application.
The sub-processes are as follows:
a) fermentation or up-stream-phase;
b) recovery and purification or down-stream-phase;
The fermentation process is based on the ability of a bacteria microorganism, of the Ralstonia eutropha species, to metabolise carbon sources and convert them to polyhydroxyalkanoates (PHA).
The carbon sources used have variable origins, e.g.:
beet industry by-products
cane industry by-products
glycerol, including crude glycerol such as the biodiesel by-product
oils and fats of various origin.
An initial growth phase encourages the proliferation of the bacterial biomass, i.e. the number of cells present; to this end:
- we provide all the necessary nutritional elements in order for the microorganism to duplicate as quickly as possible;
- we adjust process parameters (pH, temperature and pressure) to create the optimum environment for rapid growth;
- we have several vegetative propagation phases in a series of fermenters, in order to separate productive time from the dead time of biomass growth.
The microorganism used is entirely free from pathogenicity, so there is no danger to operators or those living in the surrounding area.
The essential purposes of the fermentation process are:
-to obtain a high conversion yield from substrate to polyhydroxyalkanoate (PHA);
-to obtain a high yield of polyhydroxyalkanoate (PHA) per unit of time.
As indicated previously, some production phases have no impact from a time point of view on hourly output, because they occur in parallel with the actual fermentation phase; these ancillary phases are:
- growth of the microorganism in the vegetative phases, in conical flask and fermenter;
- sterilising treatment of the co-product containing the carbon source;
- preparation of feed solutions integrating the bacterial metabolism.
At the end of the fermentation process, the resulting broth rich in polyhydroxyalkanoate (PHA) is rapidly removed in order to wash and sterilise the fermenter in preparation for the subsequent inoculum.
b) Recovery and purification.
The purpose of the recovery phase (the term used in the fermentation field) is to extract the molecule in question from the fermented broth mixture, until obtaining a highly pure raw product, which is refined to commercial level in the purification phase.
At the end of the process, the microorganism has a biomass of up to 80% polyhydroxyalkanoate (PHA), contained within the cell wall; therefore the purification phase of Bio-on's technology is part of the family of processes in which extraction involves the destruction of the cell. 20% of the biomass is made up of protein, plasma membranes, cytoplasmic content in general, treatable with standard purification processes.
The merit of Bio-on's technology, designed firstly to maintain its eco credentials and secondly to guarantee the biobased origin of the carbon contained and used in the process, lies in the fact that it does not use organic solvents such as chloroform or acetone, which have a negative impact on the environmental and are a high-cost part of the production process.