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Antibiotic resistance genes (ARGs) have been regarded as an emerging pollutant in municipal wastewater treatment plant (WWTP) effluents due to their potential risk to human health and ecological safety when reused for landscape and irrigation. Conventional wastewater treatment processes generally fail to effectively reduce ARGs, especially extracellular ARGs (eARGs), which are persistent in the environment and play an important role in horizontal gene transfer via transformation. Herein, an integrated process of pre-coagulation and microfiltration was developed for removal of ARGs, especially eARGs, from wastewater effluent. Results show that the integrated process could effectively reduce the absolute abundances of total ARGs (tARGs) (>2.9 logs) and eARGs (>5.2 logs) from the effluent. The excellent performance could be mainly attributed to the capture of antibiotic resistant bacteria (ARB) and eARGs by pre-coagulation and co-rejection during subsequent microfiltration. Moreover, the integrated process exhibited a good performance on removing common pollutants (e.g., dissolved organic carbon and phosphate) from the effluent to improve water quality. Besides, the integrated process also greatly reduced membrane fouling compared with microfiltration. These findings suggest that the integrated process of pre-coagulation and microfiltration is a promising advanced wastewater treatment technology for ARGs (especially eARGs) removal from WWTP effluents to ensure water reuse security. Image 1 • Integrated pre-coagulation and microfiltration effectively reduced tARGs and eARGs. • Capture of ARB and eARGs by Fe-coagulated flocs enhanced ARGs removal. • Pre-coagulation effectively mitigated membrane fouling. [ABSTRACT FROM AUTHOR]

Abstract Municipal wastewater treatment plants (WWTPs) are an important reservoir for heavy metal (e.g., Hg and Ag) resistance genes and antibiotic resistance genes (ARGs). However, current knowledge on Hg/Ag resistance genes and their association with ARGs in WWTPs remains largely unknown. In this study, the fates of five Hg/Ag resistance genes (merB, merD, merR, silE, and silR), five ARGs (sulI, sulII, tetO, tetQ, tetW), and class 1 integrase (intI1) in a WWTP were investigated. Results show that the absolute abundances of all target genes were greatly reduced through the treatment systems. The dynamics of merB, merD and silE were significantly correlated with tetW and sulII. Based on network analysis, Hg/Ag resistance genes might share the same microbial hosts with tetQ and tetW, implying the potential importance of Hg/Ag in ARGs evolution and spread. These findings advanced our understanding of the occurrence of Hg/Ag resistance genes and ARGs in WWTPs. Graphical abstract Unlabelled Image Highlights • Hg/Ag resistance genes were correlated significantly with ARGs in WWTP. • Hg/Ag resistance genes and ARGs shared mutual potential host bacteria. • Absolute abundances of target genes were greatly reduced through treatment process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Applied voltage improved performances of AnEMBR in treating high CTC wastewater. • Applied voltage greatly reduced ARGs abundances in effluent of AnEMBR. • HGT and microbial community shift contributed to ARGs proliferation in sludge. • Enriched tetracycline degradation gene at 0.7 V reduced ARGs selection pressure. The spread of antibiotics and antibiotic resistance genes (ARGs) in environments has posed potential threats to public health. Unfortunately, conventional biological wastewater treatment technologies generally show insufficient removal of antibiotics and ARGs. Bioelectrochemical systems, which can effectively degrade refractory organic pollutants via enhancing microbial metabolisms through electrochemical redox reaction, may provide an alternative for the control of antibiotics and ARGs. Herein, an anaerobic electrochemical membrane bioreactor (AnEMBR) was conducted by combining bioelectrochemical system and anaerobic membrane bioreactor to treat antibiotic-containing wastewater. The AnEMBR at open circuit showed stable CH 4 production and high removal of COD and chlortetracycline (CTC) in treating 2.5–15 mg/L CTC. However, increasing CTC to 45 mg/L completely inhibited the methanogenesis of AnEMBR at open circuit. After applying external voltage in AnEMBR, the performances of AnEMBR were significantly improved (e.g. , increased CH 4 production and CTC removal). Moreover, CTC exposure significantly increased the relative abundances of ARGs in sludge, supernatant, and effluent in AnEMBR at open circuit. Applying voltage greatly attenuated the total relative abundances of ARGs in the supernatant and effluent of AnEMBR compared to those at open circuit. This could be attributed to the enrichment of tetracycline degradation gene tetX , which greatly enhanced the removal of CTC by the AnEMBR and thus reduced the selective pressure of CTC on the microorganisms in supernatant and effluent for ARGs proliferation. These results would provide an effective wastewater treatment technology for treating high-level antibiotic-containing wastewater to mitigate the potential risk of ARGs and antibiotics spread in receiving water body. [ABSTRACT FROM AUTHOR]

Abstract: We report the evolution of photoluminescence (PL) of Si nanocrystals (nc-Si) embedded in a matrix of SiO2 during Ar+ ion bombardment. The integrated intensity of nc-Si PL falls down drastically before the Ar+ ion fluence of 1015 ionscm−2, and then decreases slowly with the increasing ion fluence. At the meantime, the PL peak position blueshifts steadily before the fluence of 1015 ionscm−2, and then changes in an oscillatory manner. Also it is found that the nc-Si PL of the Ar+-irradiated sample can be partly recovered after annealing at 800°C in nitrogen, but can be almost totally recovered after annealing in oxygen. The results confirm that the ion irradiation-induced defects are made up of oxygen vacancies, which absorb light strongly. The oscillatory peak shift of nc-Si can be related to a size-distance distribution of nc-Si in SiO2. [Copyright &y& Elsevier]

Fish-associated antibiotic resistance genes (ARGs) have attracted increasing attention due to their potential risks to human beings via the food chain. However, data are scarce regarding the antibiotic resistance in fish themselves. Herein, the antibiotic resistance genes (ARGs) were assessed in the gut of four major Chinese freshwater carp (i.e., silver carp, grass carp, bighead carp, and crucian carp) from food retail markets. Results show that the abundances of target ARGs (e.g., tetA , tetO , tetQ , tetW , sulI , sulII , and bla TEM-1) and class 1 integrase (intI1) were in the range 9.4 × 10−6 - 1.6 × 10−1 and 6.7 × 10−5 - 5.2 × 10−2 gene copies per 16S rRNA gene, respectively. The sulI , sulII , and tetQ strongly correlated with silver and mercury resistance genes (e.g., silE and merR). The microbial taxa of fish gut could be partly separated among retail markets based on the PCA analysis. About 15.0% of the OTUs in fish gut were shared and 74.5% of the shared OTUs were identified as Acidobacteria , Bacteroidetes , Chloroflexi , Cyanobacteria , Firmicutes , and Proteobacteria. These phyla may constitute the core microbiota in the guts of the four Chinese freshwater carp. The possible ARG hosts were revealed based on the network analysis, and the presence of pathogen-associated resistant genera in fish gut highlights the need to fully understand their potential human health risks. Image 1 • The abundances of ARGs were quantified in the gut of Chinese freshwater carp. • SulI , sulII , and tetQ were strongly correlated with silE and merR in fish gut. • Microbial taxa of fish gut were different among retail markets. • Some pathogenic genera were observed in the gut of fish. This study investigated the abundances of ARGs and microbiota in fish gut and provided new insight on ARGs pollution in Chinese four major freshwater carp. [ABSTRACT FROM AUTHOR]

The aerobic granular sludge with larger size and more compact spherical structure generally shows excellent performance in antibiotic removal, yet little is known about the long-term effect of environmentally-relevant concentration (μg/L) of antibiotics on the proliferation of antibiotic resistance genes (ARGs) and microbial community in aerobic granules. Herein, a sequencing batch reactor (SBR) was set up with dosing different concentrations (0–500 μg/L) of tetracycline to investigate its influences on microbial communities and ARG levels in aerobic granular sludge. Results show that the bioreactor could effectively remove chemical oxygen demand (COD), nitrogen, and tetracycline during the long-term operation. The quantitative polymerase chain reaction (qPCR) analysis shows that tetracycline at μg/L level could greatly enhance the absolute and relative abundances of tetA , sulII , and bla TEM - 1 in the effluent and aerobic granules, indicating tetracycline could serve as a selection pressure on the development of ARGs corresponding to different types of antibiotics in aerobic granules. Pearson's correlation analysis also implies that sulII and bla TEM - 1 were correlated strongly with tetA. Moreover, the presence of tetracycline altered the microbial communities and diversity of the effluent and aerobic granules in the bioreactor. These findings would advance our understanding of the proliferation and development of ARGs in aerobic granules under tetracycline pressure and serve as a foundation to guide the application of aerobic granular sludge for treatment of antibiotic-containing wastewater. Unlabelled Image • Tetracycline did not inhibit the performance of bioreactor in pollutant removal. • Tetracycline altered microbial community and diversity of aerobic granular sludge. • Long-term pressure of tetracycline could co-enrich tetA , sulII , and bla TEM - 1. • sulII and bla TEM - 1 were strongly correlated with tetA in aerobic granular sludge. [ABSTRACT FROM AUTHOR]

• Discarded face mask was a vital source of micro(nano)plastics and organic chemicals. • Face mask earloops released more pollutants than their filtering layers at same mass. • Toxicogenomics-based assay was used to evaluate the genotoxicity of emitted pollutants. • Membrane and DNA stress were primary responses upon exposure to emitted pollutants. Micro(nano)plastics widely detected in aquatic environments have caused serious threat to water quality security. However, as a potential important source of micro(nano)plastics in surface water during the COVID-19 pandemic, the ecological risks of face mask waste to aquatic environments remain poorly understood. Herein, we comprehensively characterized the micro(nano)plastics and organic compounds released from four daily used face masks in aqueous environments and further evaluated their potential impacts on aquatic ecosystem safety by quantitative genotoxicity assay. Results from spectroscopy and high-resolution mass spectrum showed that plastic microfibers/particles (∼11%-83%) and leachable organic compounds (∼15%-87%) were dominantly emitted pollutants, which were significantly higher than nanoplastics (< ∼5%) based on mass of carbon. Additionally, a toxicogenomics approach using green fluorescence protein-fused whole-cell array revealed that membrane stress was the primary response upon the exposure to micro(nano)plastics, whereas the emitted organic chemicals were mainly responsible for DNA damage involving most of the DNA repair pathways (e.g., base/nucleotide excision repair, mismatch repair, double-strand break repair), implying their severe threat to membrane structure and DNA replication of microorganisms. Therefore, the persistent release of discarded face masks derived pollutants might exacerbate water quality and even adversely affect aquatic microbial functions. These findings would contribute to unraveling the potential effects of face mask waste on aquatic ecosystem security and highlight the necessity for more developed management regulations in face mask disposal. [Display omitted] [ABSTRACT FROM AUTHOR]

• Thermal/alkaline pretreatment and MFC were used to recover energy from WAS. • High power density was obtained in the MFC operated under alkaline condition. • Methanogens were completely restrained and the electricigens were enriched. • Completely inhibited CH 4 emission and CO 2 release were achieved in the MFC. Energy and resource recovery from waste activated sludge (WAS) is promising for WAS treatment. Microbial fuel cell (MFC) is an environmentally friendly technology for energy recovery from WAS. Low hydrolysis rate and high methanogenic activity of WAS restrained the efficient electricity production in MFC operated at neutral pH. In this study, a combination of thermal/alkaline sludge pretreatment (140 °C, pH 12.5, 40 min) with MFC was developed, aiming to achieve high electricity generation and sludge reduction. Results show that a high power density (1.24 W/m2) was obtained in the MFC operated under alkaline condition. Complete restriction of methane production was achieved using the supernatant of thermal/alkaline pretreated WAS as substrate. 49.0 ± 3.4% of chemical oxygen demand (COD) was removed in the MFC. A low external resistance was favorable for COD removal and the accumulation of electricigens. This work provides a promising strategy for efficient sludge reduction, enhanced energy and resource recovery, as well as reduced greenhouse gas emission. [ABSTRACT FROM AUTHOR]