Automation control system of an equipment for ELF stimulated phototrophic microalgae production

The paper presents an automation system based on a programmable logic controller (PLC) for the optimal exploitation of a phototrophic equipment for microalgae growth stimulated in extremely low frequency (ELF) electric field. Through dedicated software, various transducers (pH, temperature, dissolved oxygen, luminous flux, level, turbidity, gas flow rate, etc.) and execution elements (pumps, solenoid valves, etc.), the system ensures both controlling and keeping constant the operating parameters as well as the technological command sequences, including the in-situ determination of the proper stimulation frequency. The connection via a secure industrial Ethernet network of the PLC to a SCADA computer ensures both the monitoring, storage and analysis of the registered process operating parameters, as well as the remote intervention of the process operator, via the Internet, in order to change some parameters when necessary.