A basic pH control system for multiple fermentation vessels

Several companies are offering fermentation systems that allow for multiple simultaneous fermentation vessels with independent controls (temperature, pH, oxygen, agitation, antifoam, etc.). However, some fermentations may not require all the offered control and may only need basic pH control (e.g., ethanol, anaerobic digestion). In this work, we describe the construction of a pH control system for four fermentation vessels assembled at relative low cost. Control and data collection was implemented via an Excel spreadsheet, interacting with a Data Acquisition (DAQ) module (LabJack, Lakewood, CO) that received pH probe input and controlled a set of relays connected to pinch valves for dispensing base (NaOH). The control system was tested with ANKOM Technology RF Gas Production System (Macedon, NY) vessels used for ethanol fermentation with continuous gas production monitoring.