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Chitosan-pectin gel beads (CPBs) were synthesized via a facile and green method and applied to remove heavy metals from aqueous solution. The structural characteristics of CPBs were investigated by SEM and FTIR, the mechanical strength of CPBs was measured by Texture Analyzer and the stability of CPBs was evaluated in acidic solution. To study the adsorption characteristics, the effect of pH, contact time, initial heavy metals concentration, temperature, adsorption mechanism and regeneration were systematically investigated. The adsorption kinetics fitted well pseudo-second-order model, and the adsorption isotherms were well described by Langmuir model. The maximum adsorption capacities of Cu(II), Cd(II), Hg(II) and Pb(II) were 169.4, 177.6, 208.5 and 266.5 mg/g, respectively. The adsorption-desorption experiments revealed that the CPBs exhibited a great reusability. Thus, the synthesized CPBs in this study had the potential to be utilized as an environment-friendly and green adsorbent for the removal of heavy metals. [Display omitted] • Synthesis of novel green chitosan-pectin gel beads (CPBs) for removing heavy metals • Addition of pectin greatly increased the stability, porosity and adsorption capacities of CPBs. • Adsorption of heavy metals was due to chemisorption, followed the pseudo-second-order model. • Adsorption-desorption studies emphasized the reusability performance of CPBs. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the UV and algal contribution in an intimate coupling UV irradiation and algal treatment to remove two commonly used antibiotics, cefradine and amoxicillin (AMX), including the compatibility of UV wavelength and the algal species, the removal efficiency evaluation and the microbic impact assessment. The green algae Chlorella pyrenoidosa , Selenastrum capricornutum and Scenedesmus obliquus achieved a satisfactory growth capacity and played a dominant role during the treatment. The optimal application involved the UV-irradiation at 365 nm combined the green algae S. obliquus . After 24 h, the excellent removal efficiency (99.84%) was obtained after the treatment. Our results indicated that the green algae performed a satisfactory growth capacity under the UV irradiation and played a dominant role for the biodegradation of the target antibiotics and the UV irradiation has been viewed as trigger for the algal treatment. Compared with the traditional biotechnology, the advantages of the intimate coupling treatment included high removal efficiency, energy conservation during the treatment, and low environmental impact after the treatment. [ABSTRACT FROM AUTHOR]

The goal of this research was to investigate the performance of constructed wetlands (CWs) for the removal of dissolved organic carbon (DOC) and access the possible, formation of disinfection by-products (DBP S ) after CWs treatment. A mixture of raw water from Yangtze River was spiked directly into pilot-scale CWs to assess impacts on various factors, including the removal of DOC, ultraviolet absorbance at 254 nm (UV 254 ), specific ultraviolet Absorbance (SUVA), disinfection by-products formation potential (DBPFP), trihalomethane formation potential (THMFP), and haloacetic formation potential (HAAFP). The average removal of COD Mn , NH 4 + -N, TN, DOC, UV 254 , THMs, and HAAs were 38.40%, 41.70%, 25.90%, 30.96%, 47.58%, −20.52%, and 25.22% respectively. CWs could degrade complicated organic matter into those with lower molecular weight, but could not further change to carbon dioxide and water. The average molecular weight of THMs in effluent flow declined to the level below, and high molecular weight organic compounds were more likely to form HAAs. The SUVA had no obvious relationships with the removal of specific trihalomethane formation potential (STHMFP), but had apparent relationship with the removal of specific haloacetic formation potential (SHAAFP) in CWs (p < 0.5), suggesting that aromatic moieties had a higher apparent propensity to form HAAs than THMs. [ABSTRACT FROM AUTHOR]

In this work, the novel pulse “electrosorption-electrooxidation-electrosorption” (PESO) mode is developed in the superimposed pulse current system for benzoic acid oxidation. Due to the synergistic effect of electrosorption and electrooxidation at TiO 2 -NTs/3D-SnO 2 -Sb electrode in PESO mode, the enhancement of removal efficiency, improvement in mass transport and decrease of energy consumption were significantly obvious. The mechanism for the great enhancement of the mode is analyzed in details. The strengthened interaction between electrode and organics, increased instantaneous currents and lower intermediate accumulation contributed to the significant enhancement of electrochemical performance of the superimposed pulse system. The pulse PESO mode was an efficient and promising method for treating organic pollutants. [ABSTRACT FROM AUTHOR]

Persistence of antibiotics in aquatic environment may pose a risk to the non-target aquatic organisms. This study provided an integrated evaluation to analyze the toxic stress of sulfamethazine (SMZ) on zebrafish in two lifespan stages (embryo-larval and adult) and three exposure periods (exposure, post-exposure and re-exposure). Zebrafish embryos and adult zebrafish were exposed to SMZ at 0.2, 20 and 2000 μg/L, respectively. The results showed that SMZ at any given concentration inhibited the hatching of embryos at 58–96 hpf (hours post-fertilization). Our result also indicated that two major kinds of the malformation, which was induced by the antibiotic, were edema and spinal curvature. Additionally, the antibiotic stimulated the heartbeat while reduced the body length of the embryo at 72 hpf. Superoxide dismutase (SOD) activities and malondialdehyde (MDA) contents significantly increased at 120 hpf when the embryos were exposed to the lowest concentration (0.2 μg/L) of the antibiotic. On the other hand, the antibiotic induced SOD activities and MDA contents in adult zebrafish in the exposure and re-exposure periods. The MDA contents could recover while SOD activities still increased in 2 d after the exposure. Both SOD activities and MDA contents could recover in 7 d after the exposure. Levels of SOD and MDA in the re-exposure were higher than those in the first exposure. Our results suggested that SMZ had toxic effects on both embryos and adult zebrafish, and provided an integrated evaluation of the toxic effects of SMZ on zebrafish at a new perspective. [ABSTRACT FROM AUTHOR]

In Hevea brasiliensis , the laticifers, a green factory of natural rubber, are specialised vessels in which rubber biosynthesis is the main metabolism, and fresh rubber occupies 35–45% volume of latex (the cytoplasm of laticifers). Intriguingly, Latex can be reproduced, drawing on three essential components (i.e., ATP, Acetyl-CoA and NADPH) from glycolysis in laticifers during tapping (a simple collection method). Some related key genes of sucrose loading and cleavage have been identified, such as HbSUT3/HbSUT1a , HbNIN2 , and surely more genes in TCA cycle will be exploited. Besides the aerobic respiration, the anaerobic fermentation is found highly active in laticifers, however, the role of anaerobic metabolism in laticifers remains unclear. In view of the essential role of anaerobic respiration in helping plant survive adverse conditions by supplementing ATP and intermediate metabolites, we hypothesised that it would be involved in rubber biosynthesis in similar way. To assess the role of anaerobic metabolism in laticifers, two main fermentation genes, lactate dehydrogenase (LDH) and pyruvate decarboxylase (PDC) were analysed and characterised on their gene transcription, protein expression, enzyme activities, and the corresponding metabolites flux in response to tapping treatments. Our comprehensive results revealed that the available ATP decreased rapidly with tapping, accompanying by the increasement of dry rubber yield. Moreover, HbLDH1 and HbPDC4 were identified as the key genes in anaerobic metabolism of laticifers, and they were activated by tapping，indicated by a 3.4 - fold decrease in lactate content and a 4.6 - fold increase of acetaldehyde. In addition, the levels of both acetate and acetyl-CoA decreased rapidly. These results suggested that anaerobic metabolism is indispensable to laticifers, and furthermore the synergistic regulation between ethanol and lactate fermentation has been predicted to be involved in rubber biosynthesis by providing ATP or possible intermediate material acetate. A schematic diagram of anaerobic fermentation that contributes to rubber synthesis after tapping was hereby established. • Anaerobic fermentation in laticifers is largely involved in rubber synthesis. • HbLDH1 and HbPDC4 are key genes in anaerobic metabolism of the laticifers. • The transition from lactate to ethanol fermentation occurs with tappings. [ABSTRACT FROM AUTHOR]

• Microrespirometry was applied to examine organic carbon effect on N 2 O biokinetics. • Organic carbon type noticeably affects the performances of N 2 O-reducing bacteria. • Acetate and succinate result in high oxygen and N 2 O consumption rates. • Resilience of N 2 O reductase depends on bacterial species and organic carbon type. • Genotypes of organic carbon metabolisms explain N 2 O consumption biokinetics. Harnessing nitrous oxide (N 2 O)-reducing bacteria is a promising strategy to reduce the N 2 O footprint of engineered systems. Applying a preferred organic carbon source as an electron donor accelerates N 2 O consumption by these bacteria. However, their N 2 O consumption potential and activity when fed different organic carbon species remain unclear. Here, we systematically compared the effects of various organic carbon sources on the activity of N 2 O-reducing bacteria via investigation of their biokinetic properties and genomic potentials. Five organic carbon sources—acetate, succinate, glycerol, ethanol, and methanol—were fed to four N 2 O-reducing bacteria harboring either clade I or clade II nosZ gene. Respirometric analyses were performed with four N 2 O-reducing bacterial strains, identifying distinct shifts in DO- and N 2 O-consumption biokinetics in response to the different feeding schemes. Regardless of the N 2 O-reducing bacteria, higher N 2 O consumption rates, accompanied by higher biomass yields, were obtained with acetate and succinate. The biomass yield (15.45 ± 1.07 mg-biomass mmol-N 2 O−1) of Azospira sp. strain I13 (clade II nosZ) observed under acetate-fed condition was significantly higher than those of Paracoccus denitrificans and Pseudomonas stutzeri , exhibiting greater metabolic efficiency. However, the spectrum of the organic carbon species utilizable to Azospira sp. strain I13 was limited, as demonstrated by the highly variable N 2 O consumption rates observed with different substrates. The potential to metabolize the supplemented carbon sources was investigated by genomic analysis, the results of which corroborated the N 2 O consumption biokinetics results. Moreover, electron donor selection had a substantial impact on how N 2 O consumption activities were recovered after oxygen exposure. Collectively, our findings highlight the importance of choosing appropriate electron donor additives for increasing the N 2 O sink capability of biological nitrogen removal systems. [Display omitted] [ABSTRACT FROM AUTHOR]