Nickel foam as a new material for chlortetracycline electrochemical oxidation: Biodegradability improvement and biological treatment

A combination of microbial electrolysis cells and bioaugmentation can effectively treat synthetic wastewater containing polycyclic aromatic hydrocarbon

The anaerobic biodegradation of polycyclic aromatic hydrocarbons (PAHs) is challenging due to its toxic effect on the microbes. Microbial electrolysis cells (MECs), with their excellent characteristics of anodic and cathodic biofilms, can be a viable way to enhance the biodegradation of PAHs. This work assessed different cathode materials (carbon brush and nickel foam) combined with bioaugmentation on typical PAHs-naphthalene biodegradation and analyzed the inhibition amendment mechanism of microbial biofilms in MECs. Compared with the control, the degradation efficiency of naphthalene with the nickel foam cathode supplied with bioaugmentation dosage realized a maximum removal rate of 94.5 ± 3.2%. The highest daily recovered methane yield (227 ± 2 mL/gCOD) was also found in the nickel foam cathode supplied with bioaugmentation. Moreover, the microbial analysis demonstrated the significant switch of predominant PAH-degrading microorganisms from Pseudomonas in control to norank_f_Prolixibacteraceae in MECs. Furthermore, hydrogentrophic methanogenesis prevailed in MEC reactors, which is responsible for methane production. This study proved that MEC combined with bioaugmentation could effectively alleviate the inhibition of PAH, with the nickel foam cathode obtaining the fastest recovery rate in terms of methane yield.

Integration of electrochemical processes in a treatment system for landfill leachates based on a membrane bioreactor

The use of electrocoagulation (EC) and anodic oxidation (AO) processes was studied for improving a treatment system for landfill leachates based on a membrane bioreactor (MBR) and a nanofiltration step. The main limitation of the current full-scale system is related to the partial removal of organic compounds that leads to operation of the nanofiltration unit with a highly concentrated feed solution. Application of the EC before the MBR participated in partial removal of the organic load (40 %) with limited energy consumption (2.8 kWh m-3) but with additional production of iron hydroxide sludge. Only AO allowed for non-selective removal of organic compounds. As a standalone process, AO would require a sharp increase of the energy consumption (116 kWh for 81 % removal of total organic carbon). But using lower electric charge and combining AO with EC and MBR processes would allow for achieving high overall removal yields with limited energy consumption. For example, the overall removal yield of total organic carbon was 65 % by application of AO after EC, with an energy consumption of 21 kWh m-3. Results also showed that such treatment strategy might allow for a significant increase of the biodegradability of the effluent before treatment by the MBR. The MBR might then be dedicated to the removal of the residual organic load as well as to the removal of the nitrogen load. The data obtained in this study also showed that the lower electric charge required for integrating AO in a coupled process would allow for strongly decreasing the formation of undesired by-products such as ClO3- and ClO4-.

A Review of Stand-Alone and Hybrid Microbial Electrochemical Systems for Antibiotics Removal from Wastewater

The growing concern about residual antibiotics in the water environment pushes for innovative and cost-effective technologies for antibiotics removal from wastewater. In this context, various microbial electrochemical systems have been investigated as an alternative to conventional wastewater technologies that are usually ineffective for the adequate removal of antibiotics. This review article details the development of stand-alone and hybrid or integrated microbial electrochemical systems for antibiotics removal from wastewater. First, technical features, antibiotics removal efficiencies, process optimization, and technological bottlenecks of these systems are discussed. Second, a comparative summary based on the existing reports was established to provide insights into the selection between stand-alone and hybrid systems. Finally, research gaps, the relevance of recent progress in complementary areas, and future research needs have been discussed.