In-Situ Stability Control of Energy-Producing Anaerobic Biological Reactors through Novel Use of Ion Exchange Fibers

Anaerobic biological treatment of high-strength organic industrial wastes is preferred over aerobic treatment as it produces a methane-rich biogas, has much lower energy requirements, and produces significantly less biosolids. Process stability and reactor failure are of concern, however, for waste streams that exhibit large variations in organic loading, which can cause detrimental pH fluctuations, and that have the potential for accidental input of toxic metals. Here, we demonstrate for the first time that the use of ion exchange fibers (IXFs) can provide passive resilience to these failure modes, without requiring operator oversight or reactive process control via chemical addition. IXFs have the advantage of rapid kinetics due to their small size, and they can be readily inserted and withdrawn as woven mats or porous pillows. This approach is demonstrated here using the weak-acid IXF FIBAN X-1 and the strong-base FIBAN A-1. FIBAN X-1 passively stabilized anaerobic reactors by (i) buffering pH fluctuations resulting from organic overloading due to both an increase in organic concentration and a decrease in hydraulic residence time and (ii) moderating shock-loads of copper and nickel. FIBAN X-1 also retained ∼95% of its exchange capacity after one year of operation in anaerobic reactors, demonstrating its long-term performance. In addition, FIBAN A-1 stabilized anaerobic reactors to input of chromate. These results demonstrate that IXFs can be used to passively stabilize anaerobic biological reactors from upset and failure and that this technology can be used to enhance energy recovery from high-strength organic waste streams