Methodology
The aim of this task was to assess the applicability of chosen thermo-plastic materials as a construction materials for BES reactors under specified (defined) process conditions. 5 different filaments identified in preliminary studies as the most suitable for such systems were tested in terms of their resistance to various factors, such as temperature, pressure, stress (push) and pH. Also their biocompatibility with biofilm microorganisms was investigated, together with the leaching tests that could confirm/neglect the toxicity of applied thermo-plastic materials against biota. The measurements of Young’s Modulus were taken prior and after the biological process and then compared, to determine the influence of process conditions on mechanical properties of the reactor and provide any necessary data for further reactor designing.
Different structures printed as well as different process conditions are applied for investigation of the influence of process conditions on the material properties. The lists of measured parameters together with the selected type of printed structure are collected in Tab. 1.
| Printed structure | Tested parameters | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
plates |
|
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|
sculls |
Young’s Modulus (mechanical strength) | ||||||||||||
|
trapezoidal MEBR |
Tightness tests, helium gas, exposition to an increasing pressure of max. 5,0 bar. |
For the tests with the use of plates, 3 pieces of each material was suspended in sealable bottles. The bottles were filled with required solutions. The tested materials were outlined on a previously prepared paper sheet and a 3d photos of the fresh pieces (3d microscope) were taken. The bottles were opened and the materials inspected every 2 to 3 days. Any changes observed were recorded (pictures with 3d microscope/measurements on previously used paper sheet) and noted in the dedicated table/file.
For the tests with the use of sculls, 6 sculls of each filaments were placed in the printed reactor filled with the microorganisms and all liquid media required to conduct biosynthesis. The reactor was connected to potentiostat and the voltage was set on 1V. After 21 days of operation the sculls were taken out and sent for analysis (Young’s Modulus) together with untreated sculls of tested materials.
The detailed methodology of each experiment is given below.