In a microbial bioelectrochemical system (BES) living microorganisms catalyze the anodic oxidation of organic matter at a low anode potential. We used a BES with a biological anode to power the cathodic recovery of Cu, Pb, Cd, and Zn from a simulated municipal solid waste incineration ash leachate. By varying the control of the BES, the four metals could sequentially be recovered from a mixed solution by reduction on a titanium cathode. First, the cell voltage was controlled at zero, which allowed recovery of Cu from the solution without an electrical energy input. Second, the cathode potential was controlled at -0.51 V to recover Pb, which required an applied voltage of about 0.34 V. Third, the cathode potential was controlled at -0.66 V to recover Cd, which required an applied voltage of 0.51 V. Finally, Zn was the only metal remaining in solution and was recovered by controlling the anode at +0.2 V to maximize the generated current. The study is the first to demonstrate that a BES can be used for cathodic recovery of metals from a mixed solution, which potentially could be used not only for ash leachates but also for e.g. metallurgical wastewaters and landfill leachates.

Summary The molecular mechanism of leaf senescence in apple (Malus domestica) is still not fully understood. We used gene expression analysis and protein–protein interactions to decipher the relationships of abscisic acid (ABA) and two proteins, MdbHLH93 and MdBT2, in the senescence process. We found that MdbHLH93 promoted leaf senescence and the expression of senescence‐related genes, which exhibited similar effects to ABA on leaf senescence. MdbHLH93 activated directly the transcription of MdSAG18. We also found that an ABA‐responsive protein, MdBT2, interacted directly with MdbHLH93, and induced the ubiquitination and degradation of the MdbHLH93 protein, and thus delayed leaf senescence. Our findings provide new insights into the regulatory network of leaf senescence through the functional interactions among ABA, MdbHLH93 and MdBT2.

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High energy input and chemical additions are typically needed to deal with persistent pollutants, organic and inorganic, and organometallic complexes in wastewater. Particularly, organometallic complexes decrease the removal efficiency for other pollutants being treated with conventional technologies, which can lead to high operational costs and residues formation. The improperly treated wastewater contains nutrients (nitrogen and phosphorus), heavy metals, and persistent organics, which should be removed or recovered before discharging. Electrochemical technologies can achieve concomitant removal of persistent pollutants and resource recovery from wastewater, with the benefits of low chemical input, cost-effectiveness and reduced water consumption. Here, we provide an overview of electrochemical technologies for the separation of organics and inorganics and their subsequent recovery. The focus is placed into electrodeposition, electrodialysis, membrane electrolysis, electrochemical oxidation, capacitive deionization, and bioelectrochemical systems. The main challenges considered at present are i) the cost and longevity of the materials, ii) the process efficiency and selectivity and iii) the complexity of the wastewater matrices. In this review it is projected that in the near future, the electrochemical separation and recovery of organics and inorganics will be preferred, as electrochemical cells powered by renewable energy can serve for decentralized and off-grid treatment approaches.

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