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Abstract: Spent Ni–Cd batteries bring a severe environmental problem that needs to be solved urgently. A novel continuous flow two-step leaching system based on bioleaching was introduced to dissolve heavy metals in batteries. It consists of an acidifying reactor which was used to culture indigenous thiobacilli and a leaching reactor which was used to leach metals from spent batteries. The indigenous acidophilic thiobacilli in sewage sludge was used as the microorganisms and the sludge itself as culture medium. Bioleaching tests at different hydraulic retention time (HRT) and process load in the leaching reactor were performed. The results showed that the longer the HRT (1, 3, 6, 9 and 15 days) was, the more time required to achieve the complete leaching of Ni, Cd and Co. The maximum dissolution of cadmium and cobalt was achieved at higher pH values (3.0–4.5) while the leaching of nickel hydroxide and nickel in metallic form (Ni0) were obtained separately in different acidity (pH 2.5–3.5). It cost about 25, 30 and more than 40 days to remove all of the three heavy metals with the process load of two, four and eight Ni–Cd batteries under the conditions that the ingoing bio-sulphuric acid was 1Ld−1 and HRT was 3 days. [Copyright &y& Elsevier]

The prevalence of various antibiotic resistance genes (ARGs) and resistant bacteria has caused global public health risks. The carrier transport mediated by phages or membrane vesicles is an important way for horizontal transfer of ARGs. Nano metal oxide particles (NMOPs), which can enter cell through the cell membrane, may be used as the carriers of genes. However, whether they can be used as transmembrane delivery vectors for the horizontal ARG transfer remains unknown. Here, we set up a model of MONPs-mediated transfer of ARGs, and demonstrate that NMOPs, especially for nano-Al 2 O 3 , can act as carriers mediating the transduction-like ARG transformation in water. The highest transfer rate mediated by nano-Al 2 O 3 is 4.53 × 104 cfu/mmol, and it is 104 times higher than that of control. Nano-Al 2 O 3 can combine with plasmid coding for ARGs to form high-density package and prevent ARGs from degradation by endonuclease. The results of superresolution fluorescence microscopy and transmission electron microscopy show that nano-Al 2 O 3 can carry ARGs for transmembrane transport. Genome-wide transcription microarray and qPCR indicate that SOS response was closely related to transduction-like ARG transformation mediated by nano-Al 2 O 3. This study is the first to demonstrate that as a new transmembrane carrier, nano-Al 2 O 3 can also cause ARGs diffusion in water. ga1 • Nano-Al 2 O 3 can cause ARGs diffusion through transduction in water. • Nano-Al 2 O 3 prevents ARGs from degradation by endonuclease. • SOS response is closely related to ARG transduction mediated by nano-Al 2 O 3. [ABSTRACT FROM AUTHOR]