(487g) Hollow-Fiber Membrane Bioelectrochemical Reactor for Wastewater Treatment

Microbial fuel cells (MFCs) have been widely studied as a potential approach for simultaneous wastewater treatment and bioenergy production. The primary function of an MFC is wastewater treatment; however, the issues about the MFC effluent quality are not sufficiently addressed, possibly because most studies fed the MFCs using synthetic solutions that are “cleaner” than actual wastewater. A few studies that adopted actual wastewater have demonstrated an effective organic removal by MFCs, but whether the treated effluent meets the discharge standards needs further clarification. MFCs are designed to replace the secondary treatment, which usually requires a tertiary treatment such as filtration and/or disinfection for further purifying the treated effluent. To produce a high-quality effluent for either direct discharge or water reuse will make MFCs more competitive as a wastewater treatment technology.

The existing wastewater treatment accomplishes high-quality effluents using membrane bioreactors (MBR), which integrate membrane filtration using microfiltration (MF) or ultrafiltration (UF) membranes with suspended growth bioreactors. The MBR technology has been commercialized for municipal or industrial wastewater treatment. The filtration elements can be either submerged (internal) in a bioreactor such as an activated sludge tank, or installed as a sidestream (external). To recover energy from wastewater, anaerobic MBR is developed with the production of methane gas.  More details about the MBR technology can refer to several in-depth review publications.

A possible strategy to involve filtration membranes in MFCs is to use MF/UF membranes as filtration media, installed either inside or outside the anode compartment similarly to that in MBRs. Ion exchange membranes are still required to separate the electrodes, unless a membrane-less MFC is employed. In this study, we developed a membrane bioelectrochemical reactor (MBER) by installing hollow-fiber membranes inside a tubular MFC. The MBER is expected to produce high-quality water while generate electric energy from organic oxidation. A recent study reported a bioelectrochemical membrane reactor using biofilm formed on stainless steel mesh as the filtration material in an MFC, which is very different from our MBER that uses actual MF membrane as the filtration material. We have investigated the performance of the developed MBER with both synthetic solution and actual wastewater for over 150 days. Electricity generation was recorded, trans-membrane pressure was monitored and the quality of the effluent was characterized.