Abstract

The principle objectives of this research were to design and investigate a novel approach to generate an excellent quality effluent, while minimizing the size of the treatment unit and energy consumption. To achieve these objectives a submerged membrane electro-bioreactor (SMEBR) was designed and its performance was investigated. Membrane processes, electrokinetic phenomena, and biological processes take place simultaneously leading to the control of the problem of membrane fouling which has been considered one of the major challenges to widespread application of membrane bioreactor technology. This design is the first attempt to combine electrokinetic principles, using electro-coagulation (EC) processes and submerged membrane bioreactor in one reactor vessel. Both water quantity and quality were monitored through different experimental phases to verify the feasibility of the SMEBR system for wastewater treatment under various operating conditions. Firstly, a preliminary experimental phase was conducted on a small-scale electro-bioreactor (without the operation of the membrane module) to identify the best electrokinetic conditions in terms of the appropriate current density so as not to impede the biological treatment, and to determine the best exposure time of DC when it should be applied intermittently in the SMEBR system. DC field of 1 V/cm with an operational mode of 15 minutes ON/45 minutes OFF of DC power supply were found to be the adequate electrical conditions to operate the SMEBR system. Two different anode materials--iron and aluminum--were used to validate the SMEBR system for wastewater treatment. At the operating mode of 15 minutes ON/45 minutes OFF, the applied DC field in the SMEBR system enhanced the membrane filterability up to 16.6% and 21.3% using iron and aluminum electrodes respectively. However, the significant improvement in membrane filterability was 52.5% when using an aluminum anode at an operational mode of 15 minutes ON/105 minutes OFF, which indicated that the operational mode of DC supply is a key parameter in the operation of a SMEBR system. In terms of pollutants removal, the overall removal efficiency for COD was greater than 96% and greater than 98% for phosphorus. In conjunction, the removal of NH 3 -N was on average 70%. It should be emphasized that the phosphorous removal efficiency was higher than other studies on MBR without the use of electrokinetics. Furthermore, the effluent of the SMEBR treatment, using synthetic wastewater, had no color and no odor. The designed SMEBR system may find a direct application in the treatment of various wastewaters, including sewage, without an extensive pretreatment. Such a solution is required by several small municipalities, mining areas, agriculture facilities, military bases, and in cold regions. Finally, such a compact hybrid system can easily be adapted to a mobile unit