An original Arduino-controlled anaerobic bioreactor packed with biochar as a porous filter media

Bioreactors are commonly used apparatuses generally equipped with several built-in specifications for the investigation of biological treatment studies. Each bioreactor test may require different types of specialty such as heating, agitation, re-circulation and some further technologies like online sensoring. Even thought, there are many ready-to-use fabricated bioreactors available in the market with a cost usually over than 1000 €, it is often not possible to access those advanced (but inflexible) systems for many students, young-researchers or small-scale private R&D companies. In this work, a new low cost (≈100€) packed-bed anaerobic bioreactor was developed, and all methodological details including open-source coding and 3D design files are shared with informative descriptions. Some preliminary tests were conducted to verify the developed bioreactor system's credibility in terms of leak-tightness, accurate gas monitoring, temperature controlling, and mass balance (COD-eq) coverage, which all have shown a very promising performance. • A consistent model bioreactor that will be called as “tetrapod” was developed for anaerobic treatment of challenging substrates such as pyrolytic liquids. • Coarse biochar grains were used as an organic packing material to stimulate the microbial bioconversion by increasing the active surface area for the attached-growth anaerobic mixed microbial culture (MMC). • An open-source Arduino based digital gasometer was developed for online monitoring of biogas change in the lab-scale system. Arduino was also used as a digital controller for maintaining pulse-mode liquid recirculation of the bioreactor.