During the long and cold winter season in northern area of China, wastewater treatment is often inefficient which causes the substandard discharge. In this study, a lead-resistant psychrotrophilic ...bacterium was isolated and used as an adsorbent to remove Pb(II) from aqueous solution at 15°C. The strain was identified and designated as Bacillus sp. PZ-1 based on the morphology, physiological–biochemical experiments and 16S rDNA sequence analysis. The minimal inhibitory concentration and antibiotic experiments revealed that PZ-1 had high resistance to 1500mgL−1 of Zn(II), 800mgL−1 of Cu(II), 400mgL−1 of Ni(II), 15µgmL−1 of chloramphenicol and 50µgmL−1 of streptomycin, but susceptibility to 200mgL−1 of Co(II). Scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy analyses showed that biosorption of Bacillus sp. PZ-1 to Pb(II) involved surface adsorption, ion exchange and micro-precipitate. Fourier transform infrared spectroscopy analyses indicated that hydroxyl, carbonyl and carboxyl on cells may play vital roles in Pb(II) adsorption. Besides, siderophore secreted by PZ-1 had beneficial impacts on the Pb(II) removal. Biosorption experiments were carried out as a function of initial Pb(II) concentration (50–500mgL−1), pH (3.0–7.0), biomass concentration (5–50gL−1) and contact time (5–40min). Biosorption rate of 93.01% with adsorption capacity of 9.30mgg−1 was obtained under the initial Pb(II) concentration of 400mgL−1, pH of 5.0, contact time of 20min, biomass concentration of 40gL−1 and the temperature of 15°C. The equilibrium data were well fitted with Langmuir model, which indicated the adsorption process of Pb(II) is monolayer adsorption. Bacillus sp. PZ-1 appeared to be an efficient biosorbent for removing Pb(II) from wastewater at low temperature.
•Psychrotrophilic Bacillus sp. PZ-1 effectively removes Pb(II) from wastewater at 15°C.•Bacillus sp. PZ-1 expressed strong resistance to Pb(II), Zn(II), Cu(II), and Ni(II).•Biosorption of Pb(II) involved surface adsorption, ion exchange and micro-precipitate.•The equilibrium data was fitted well with Langmuir and Freundlich models.
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•Biofilm unstable adhesion phase was quantitatively characterized via RTCA on-line.•High concentrations of bacteria shorten the reversible adhesion process.•Shear stress increases the ...reversibility of bacterial adhesion.•Bacterial motility regulates the unstable adhesion process.•Proteins in EPS may substantially impact the initial adhesion process.
The initial bacterial adhesion phase is a pivotal and unstable step in the formation of biofilms. The initiation of biofilm formation is an unstable process caused by the reversible adhesion of bacteria, which is always time-consuming and yet to be elucidated. In this study, impedance-based real time cell analysis (RTCA) was employed to comprehensively investigate the initial bacterial adhesion process. Results showed that the time required for the unstable adhesion process was significantly (p < 0.05) reduced by increasing the initial concentration of bacteria, which is mainly attributed to the large deposition rate of bacteria at high concentrations. In addition, the unstable adhesion process is also regulated by shear stress, derived in this work from orbital shaking. Shear stress improves the reversibility of unstable bacterial attachment. Furthermore, attachment characteristics during the unstable phase vary between different species of bacteria (Sphingomonas rubra, Nakamurella multipartita and mixed bacteria). The S. rubra strain and mixed culture were more prone to adhere to the substratum surface during the unstable process, which was attributed to the smaller xDLVO energy barrier and motility of species in comparison with N. multipartita. Meanwhile, the molecular composition of extracellular polymeric substances (EPS) in the initial attachment phase presented a significant difference in expressed proteins, indicating the important role of proteins in EPS that strengthen bacterial adhesion. Overall, these findings suggest that during the biofilm reactor start-up process, seed sludge conditions, including the bacterial concentration, composition and hydraulics, need to be carefully considered.
This study covers three widely detected non-steroidal anti-inflammatory pharmaceuticals (NSAIDs), diclofenac (DCF), ibuprofen (IBP) and naproxen (NPX), as NSAIDs pollutants. The objective is to ...evaluate the impact of NSAIDs at their environmental concentrations on microbial community assembly and activity. The exposure experiments were conducted under three conditions (5 μg L-1 DCF, 5 μg L-1 DCF+5 μg L-1 IBP and 5 μg L-1 DCF+5 μg L-1 IBP+ 5 μg L-1 NPX) in sequencing batch reactors (SBRs) for 130 days. Removals of COD and NH4+-N were not affected but total nitrogen (TN) removal decreased. IBP and NPX had the high removal efficiencies (79.96% to 85.64%), whereas DCF was more persistent (57.24% to 64.12%). In addition, the decreased removals of TN remained the same under the three conditions (p > 0.05). The results of oxidizing enzyme activities, live cell percentages and extracellular polymeric substances (EPS) indicated that NSAIDs damaged the cell walls or microorganisms and the mixtures of the three NSAIDs increased the toxicity. The increased Shannon-Wiener diversity index suggested that bacterial diversity was increased with the addition of selected NSAIDs. Bacterial ribosomal RNA small subunit (16S) gene sequencing results indicated that Actinobacteria and Bacteroidetes were enriched, while Micropruina and Nakamurella decreased with the addition of NSAIDs. The enrichment of Actinobacteria and Bacteroidetes indicated that both of them might have the ability to degrade NSAIDs and thereby could adapt well with the presence of NSAIDs.
The platform consists of three modules, which are pre‐configured bioinformatic pipelines, cloud toolsets, and online omics' courses. The pre‐configured bioinformatic pipelines not only combine ...analytic tools for metagenomics, genomes, transcriptome, proteomics and metabolomics, but also provide users with powerful and convenient interactive analysis reports, which allow them to analyze and mine data independently. As a useful supplement to the bioinformatics pipelines, a wide range of cloud toolsets can further meet the needs of users for daily biological data processing, statistics, and visualization. The rich online courses of multi‐omics also provide a state‐of‐art platform to researchers in interactive communication and knowledge sharing.
Irrespective of which side is taken in the densification-sprawl debate, insights into the relationship between urban green space coverage and urbanization have been recognized as essential for ...guiding sustainable urban development. However, knowledge of the relationships between socio-economic variables of urbanization and long-term green space change is still limited. In this paper, using simple regression, hierarchical partitioning and multi-regression, the temporal trend in green space coverage and its relationship with urbanization were investigated using data from 286 cities between 1989 and 2009, covering all provinces in mainland China with the exception of Tibet. We found that: 1 average green space coverage of cities investigated increased steadily from 17.0% in 1989 to 37.3% in 2009; 2 cities with higher recent green space coverage also had relatively higher green space coverage historically; 3 cities in the same region exhibited similar long-term trends in green space coverage; 4 eight of the nine variables characterizing urbanization showed a significant positive linear relationship with green space coverage, with ‘per capita GDP’ having the highest independent contribution (24.2%); 5 among the climatic and geographic factors investigated, only mean elevation showed a significant effect; and 6 using the seven largest contributing individual factors, a linear model to predict variance in green space coverage was constructed. Here, we demonstrated that green space coverage in built-up areas tended to reflect the effects of urbanization rather than those of climatic or geographic factors. Quantification of the urbanization effects and the characteristics of green space development in China may provide a valuable reference for research into the processes of urban sprawl and its relationship with green space change.
► The green space coverage in Chinese cities increased steadily from 1991 to 2009. ► Cities in the same region exhibited long-term similar trends of development. ► Population, land area and GDP significantly affected green space coverage. ► Per capita GDP had the highest independent contribution to green space coverage. ► A linear model to predict variance in green space was constructed.
Regulation of process parameters is a cost-effective approach to control microorganism-derived dissolved organic nitrogen (mDON) formation in low-temperature biological wastewater conditions. ...However, the integrated influence of multiple parameters in this process is poorly defined. In this study, mathematical methodology was used to evaluate the combined effects of hydraulic retention time (HRT), solids retention time (SRT), and mixed liquor suspended solids (MLSS) on mDON formation at 8 °C. This study also systematically explored how multiple combinations of those three parameters affected mDON chemodiversity (fluorescent properties and molecular compositions), microbial compositions, and specific relationships between mDON molecules and microbial species in activated sludge systems. Results showed that combined effects significantly controlled the mDON formation at 8 °C (P < .05). The systematic analysis suggested that the multi-parameter effects modulated the distribution of different mDON compositions and shaped the microbial communities. Most bacterial phyla as the generalist and a few as the specialist were displayed in 2487 pairs of strong microbe-mDON connections (|r| ≥ 0.6, P < .05). Moreover, network analysis on microbe-mDON relationships identified the network centers as crucial media in terms of combined effects of process parameters on mDON formation. Our results provide comprehensive insight on the roles of multi-parameter covariation influences in regulating the high complexity of mDON traits and microbe-mDON linkages, thereby highlighting the necessity to focus on the combined effects of process parameters for effective and correct controlling strategies on mDON concentrations.
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•Parameter covariations significantly control mDON formation at 8 °C (P < .05).•Multi-parameter combined effects include linear and interactive functions.•mDON molecular traits exhibit different responses to different parameter combinations.•Most phyla show high connectivity with mDON molecules as network centers.•Multi-parameter covariations enable various microbe-mDON relationships.
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•Initial biofilm attachment was studied on-line and non-destructively.•Reversible biofilm adhesion was identified in the initial attachment process.•High concentration of AHLs shorten ...biofilm reversible adhesion process.•The composition of QS-related bacteria was regulated by exogenous AHLs.
Initial attachment plays an important role in biofilm formation in wastewater treatment processes. However, the initial attachment process mediated by N-acyl-homoserine lactones (AHLs) is difficult to be fully understood due to the lack of non-invasive and on-line investigation techniques. In this study, the AHL-regulated wastewater biofilm attachment was quantified using ultrasonic time-domain reflectometry (UTDR) as an in-situ and non-invasive monitoring technique. Results demonstrated that the reversible adhesion time in municipal and industrial wastewaters was significantly decreased in the presence of exogenous AHLs. Biofilm thickness in municipal and industrial wastewaters increased significantly with the addition of exogenous AHLs. Also, the addition of acylase delayed the initial biofilm formation (lengthened reversible adhesion time and decreased biofilm thickness and density). Compared with biofilm behavior in the presence of low concentrations of AHLs (4.92 ± 0.17 μg/L), both reversible adhesion time and biofilm thickness were not significantly increased (p > 0.05) with an increase in AHL concentration (9.75 ± 0.41 μg/L). Furthermore, the addition of exogenous AHLs resulted in significant changes in the attached bacterial community structures, in which both QS and quorum-quenching (QQ) bacteria were stimulated. The current work presents an effective approach to in-situ monitoring of the regulation of AHL-mediated QS in the initial attachment of biofilms, especially in the reversible adhesion process, which may provide a potential strategy to facilitate biofilm establishment in wastewater treatment processes.
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•The concentration and ecological risk of PFASs in developed districts were higher.•Four application sources of PFASs were quantitatively identified by receptor model.•PFASs were ...mainly from consumption and transportation equipment related productions.•No effective scavenging was observed and effluent PFAS levels depended on influent.
Municipal wastewater treatment plants (WWTPs) are sinks of per- and polyfluoroalkyl substances (PFASs) generated by human activities and are also sources of PFASs in aquatic environment. This study analyzed distribution, source and ecological risk of 14 PFASs in influent and effluent samples from 148 Chinese municipal WWTPs. Composition and concentrations of PFASs in the influents and effluents had obvious spatial differences. Fluoropolymer processing aids/wrappers and textile treatments/coatings were found to be the dominant sources in WWTP influents, which accounted for 78.34% of all sources. Consumption structure and metal and transportation equipment manufacturing affected the spatial differences of PFASs in WWTPs. Further, mean removal rate of total PFASs in all WWTPs was −5.45%. The conventional treatment processes can not effectively remove PFASs and no significant difference was found among different treatment processes. However, risk quotient values of PFASs in effluents were all below 0.1, indicating low risk or no risk to aquatic organisms. It should be noted that the composition, source and ecological risk of PFASs in east China were different from the other regions, which need more attentions. This study sheds insights into occurrencesof PFASs in municipal WWTPs, which should be helpful for their control strategy development.
Although N-acyl-L-homoserine lactone (AHL) based quorum sensing (QS) phenomenon has been observed in mature anaerobic granules, the biological role of AHL-based QS system in anaerobic granulation ...process remains unexplored. For the first time, a long-term anaerobic bioreactor was operated for 168 days to investigate the biological role of AHL in the granulation process which was divided into three phases (phase I: floccular, phase II: granulation, phase III: maturation). Two different AHLs including C8-HSL and C10-HSL were characterized at nanogram levels. The AHL level was elevated over 20-fold and strongly positively correlated with extracellular polymeric substances (EPS) production and sludge particle size during phase I-II. Exogenous addition of AHL to the floccular sludge also resulted in significantly increased EPS production. Metadata analysis suggested that the granulation process was accompanied by an increase in the abundance of QS-relevant microorganisms. The strong relationships (R > 0.9233, p < 0.01) among AHL concentrations, EPS (except loosely bound EPS), granulation and community variation indicated that AHL-mediated QS played an important role in coordinating community level behaviors associated with granulation, potentially through the regulation of EPS production and composition. This study gives a deep insight into the underlying QS-relevant mechanism of anaerobic granulation process.
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•The effect of carbon-to-nitrogen ratios in mDON generation dynamics was considered.•The simulation of mDON generation in four-denitrification was accurate (R2 = 0.909–0.986).•mDON ...formed in real wastewater was provided a reasonable prediction (1.16–1.63 mg/L).•Production of new nitrogenous molecules confirmed the model applicability.•High carbon-to-nitrogen ratios are of benefit to reduce effluent-associated ecological risk.
Quantifying microorganism-derived dissolved organic nitrogen (mDON) formed from microbial activities is a prerequisite for reducing effluent nitrogen. In this work, a new model based on activated sludge model for nitrogen (ASMN) is proposed for determining mDON formation together with its dynamics in post-denitrification under different carbon-to-nitrogen (C/N) ratios of 3, 4, 5, and 6. This model incorporates mDON as a separate component among four-step denitrification and introduces three new mDON-related parameters (i.e., fH,mDON, KH,mDON, and KI4SS) to develop mDON production and utilization equations. The model was calibrated and established with data from an experiment using synthetic wastewater, demonstrating its capability of accurately simulating mDON generation (R2 = 0.909–0.986). Accordingly, the simulated results successfully captured the experimental trends, suggesting that higher C/N ratios were preferred for mitigating mDON generation. The model applicability was further tested by predicting mDON generation in real wastewater, producing reasonable predicted results of formed mDON (1.16–1.63 mg/L). These predicted results were also indirectly confirmed by newly produced nitrogenous molecules (i.e., lipid-, carbohydrates-, and protein/amino sugars-like molecules). Overall, this work offers a tool to quantify mDON which benefits controlling mDON toward minimizing the adverse impacts of effluent organic nitrogen on receiving waters.
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