On the basis of the process stabilised at laboratory scale and optimised at medium-size scale, a demonstration plant for the recovery of non-tanned hide wastes has been designed, constructed and set up. The demonstration plant is located at INESCOP facilities, next to a microencapsulation pilot plant.
The selected design consists in a main reactor where both pre-treatment and extraction stages take place. Gelatine concentration can also be made in the own reactor with the help of a vacuum system.
The reactor is equipped with a thermal and a pH probe (EC meter) for the continuous control of operating conditions. Furthermore, several load cells allow the control of reagents dosage.
Alkalis and acid dosing pumps are also included, in order to maintain the required pH at each stage of the process.
A filtration system is also included, which is connected to a pumping system in order to facilitate filtering and minimize any loss of gelatine during this process.
The overall process is controlled by means of an automated control system.
A new design of experiments (DOE) for the pre-treatment phase has been performed at the demonstration plant, taking as a basis the conclusions achieved in the medium-size scale. It consisted in a 2-level full design for 3 factors (temperature, time and protease concentration), with a central point. Results obtained are in line with those achieved in the medium size-scale, obtaining the same effects tendency for both yield and Bloom properties.
Gelatines produced at the demonstration plant have also been characterised by their isoelectric point (pI), a property that affects the microencapsulation process.
By selecting the appropriate conditions, LIFE microTAN process is able to produce different grade gelatines, suitable for different applications. The table below compares properties of gelatines produced at the demonstration plant with those of commercial gelatines obtained by the conventional alkaline process (B-type gelatines).
|Properties||microTAN gelatine||Commercial B-type gelatine|
|Isoelectric point (pI)||4.9 - 5.2||4.7 - 5.2|
|Bloom value (g)||10 - 260||50 - 300|
In the case of gelatines with high Bloom values (suitable for microencapsulation), the demonstration plant key performance data can be summarised en the following table:
|Amount of by-product processed
|Yield of valorisation (depending on the hide by-product batch)||65-90%|
|Amount of valorised product||2-4 Kg gelatine|
|Whole process duration||8 h/batch|
|Water consumption||0.2 m3|
When compared with the conventional alkaline pre-treatment, the proposed process has a series of advantages, both from the environmental and the economic point of view. Significant savings in both time and water consumption are achieved with the enzymatic process. A comparison among both processes is schematised in the picture below.
This plant is available for any company interested in a demonstration test.