New open-source, self-assembly tools to study microbial activity and water treatment applications

The ability to record high-resolution data for extended periods using affordable systems can improve the study of hydrological and environmental processes. Unlike commercial alternatives, publicly available open-source sensors can be implemented at a significantly lower cost, allowing higher spatiotemporal resolution and continuous, real-time monitoring. In this presentation, I will outline the fundamental principles, advantages, and challenges of using open-source, self-assembly hardware for hydrological related monitoring using two novel systems. The first system is an incubation chamber system composed of O₂, CO₂, CH₄ low-cost sensors for monitoring gas fluxes from sludge samples, specifically tested on wetland samples under different temperature, oxygen, and light conditions. The second system consists of a portable photoreactor/spectrophotometer driven by Raspberry Pi and Arduino UNO microcontrollers. Validation tests of the photoreactor system were performed in one preliminary design for Rhodamine B dye photodegradation, in which the spectral module was constituted by seven arrays of high-power LED of different wavelengths (UVC and VIS), bismuth ferrite (BiFeO₃) catalyst, and hydrogen peroxide. Results showed significant dye degradation (39.7%) at high chamber temperature (45 °C). The performance of this system is improved in a new design, which includes an exchangeable light module, sampling system, and a spectrophotometer for real-time monitoring of the photocatalytic process in water. Complete technical guides on design, assembly, and installation are provided for both systems, aiming to promote their reproducibility and application for new microbial activity studies and laboratory water treatment applications.