Biomineralized nanoparticles for the immobilization and degradation of crude oil-contaminated soil

Accidental oil leaks and spills often cause server soil pollution,and in situ remediation is a powerful and economical treatment technology.While during in situ remediation process,unpredicted migration of petroleum hydrocarbon in heterogeneous soil will lead to a long-term source of persistent aquifer contamination.To reduce the migration of petroleum hydrocarbon and effectively improve the in situ remediation efficiency,herein,fungal biomineralization strategy was proposed for the immobilization of petroleum contaminants.A ureolytic fungi strain with crude oil-degradation ability was screened and identified as Chaetomium globosum.When incubated in medium containing Ca2+and crude oil,a mineral corona with spiny nanoparticles was formed at the edge of oil and the interface characters were analyzed using fluorescent pH and dissolved oxygen(DO)sensing films,respectively.Results indicated that biominerals preferred to aggregate around the edge of crude oil,providing favorable microenvironment for fungal growth and then leading to the increase of pH in the microenvironment,eventually accompanied by the formation of mineral corona.The mineral corona with numerous nanoparticles may act as a solid and stable shell,limiting or reducing the mobility of crude oil,and providing enough time for fungal biodegradation.After 28 days incubation,oilcontaminated soil treated with fungal biomineralization showed better immobilization ability for total petroleum hydrocarbon(TPH)under simulated acid-rain condition and higher TPH removal efficiency.This is the first demonstration for the immobilization of oil through fungal biomineralized nanoparticles,thus providing a novel strategy for the in situ remediation of oilcontaminated sites.

Comparison between UV and VUV photolysis for the pre- and post-treatment of coking wastewater

In this study, ultraviolet （UV） and vacuum ultraviolet （VUV） photolysis were investigated for the pre-treatment and post-treatment of coking wastewater. First, B-fold diluted raw coking wastewater was irradiated by UV and VUV. It was found that 15.9%-35.4% total organic carbon （TOC） was removed after 24 hr irradiation. The irradiated effluent could be degraded by the acclimated activated sludge. Even though the VUV photolysis removed more chemical oxygen demand （COD） than UV, the UV-irradiated effluent demonstrated better biodegradability. After 4 hr UV irradiation, the biological oxygen demand BODs/COD ratio of irradiated coking wastewater increased from 0.163 to 0.224, and its toxicity decreased to the greatest extent. Second, the biologically treated coking wastewater was irradiated by UV and VUV. Both of them were able to remove 37%-47% TOC within 8 hr irradiation. Compared to UV, VUV photolysis could significantly improve the transparency of the bio-treated effluent. VUV also reduced 7% more ammonia nitrogen （NH4^＋-N）, 17% more nitrite nitrogen （NO2^--N）, and 18% more total nitrogen （TN） than UV, producing 35% less nitrite nitrogen （NO3^--N） as a result. In conclusion, UV irradiation was better in improving the biodegradability of coking wastewater, while VUV was more effective at photolyzing the residual organic compounds and inorganic N-species in the bio-treated effluent.

Distribution of bacterial communities across plateau freshwater lake and upslope soils

Microorganisms are involved in a variety of biogeochemical processes in natural environments.The differences between bacterial communities in freshwaters and upslope soils remain unclear. The present study investigated the bacterial distribution in a plateau freshwater lake,Erhai Lake（southwestern China）, and its upslope soils. Illumina MiS eq sequencing illustrated high bacterial diversity in lake sediments and soils. Sediment and soil bacterial communities were mainly composed of Proteobacteria, Acidobacteria, Actinobacteria,Bacteroidetes, Chloroflexi and Planctomycetes. However, a distinctive difference in bacterial community structure was found between soil and sediment ecosystems. Water content, nitrogen and p H affected the distribution of the bacterial community across Erhai Lake and its upslope soils. Moreover, the soil bacterial community might also be shaped by plant types. This work could provide some new insights into plateau aquatic and terrestrial microbial ecology.

Tire pyrolysis wastewater treatment by a combined process of coagulation detoxification and biodegradation

Recycling waste tires through pyrolysis technology generates refractory wastewater,which is harmful to the environment if not disposed properly.In this study,a combined process of coagulation detoxification and biodegradation was used to treat tire pyrolysis wastewater.Organics removal characteristics at the molecular level were investigated using electrospray ionization(ESI)coupled with Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS).The results showed that nearly 90%of the organic matter from the wastewater was removed through the process.Preference of the two coagulants for different classes of organics in tire pyrolysis wastewater was observed.The covalently bound inorganicorganic hybrid coagulant(CBHyC)used in this work had a complementary relationship with biodegradation for the organics removal:this coagulant reduced toxicity and enhanced the biodegradation by preferentially removing refractory substances such as lignin with a high degree of oxidation(O/C>0.3).This study provides molecular insight into the organics of tire pyrolysis wastewater removed by a combined treatment process,supporting the advancement and application of waste rubber recycling technology.It also contributes to the possible development of an effective treatment process for refractory wastewater.

Experimental and computational assessment of 1,4-Dioxane degradation in a photo-Fenton reactive ceramic membrane filtration process

The present study evaluated a photo-Fenton reactive membrane that achieved enhanced 1,4-Dioxane removal performance.As a common organic solvent and stabilizer,1,4-Dioxane is widely used in a variety of industrial products and poses negative environmental and health impacts.The membrane was prepared by covalently coating photocatalyst of goethite(α-FeOOH)on a ceramic porous membrane as we reported previously.The effects of UV irradiation,H_(2)O_(2)and catalyst on the removal efficiency of 1,4-Dioxane in batch reactors were first evaluated for optimized reaction conditions,followed by a systematical investigation of 1,4-Dioxane removal in the photo-Fenton membrane filtration mode.Under optimized conditions,the 1,4-Dioxane removal rate reached up to 16%with combination of 2 mmol/L H_(2)O_(2)and UV365 irradiation(2000µW/cm^(2))when the feed water was filtered by the photo-Fenton reactive membrane at a hydraulic retention time of 6 min.The removal efficiency and apparent quantum yield(AQY)were both enhanced in the filtration compared to the batch mode of the same photo-Fenton reaction.Moreover,the proposed degradation pathways were analyzed by density functional theory(DFT)calculations,which provided a new insight into the degradation mechanisms of 1,4-Dioxane in photo-Fenton reactions on the functionalized ceramic membrane.

Multiphase redistribution differences of polycyclic aromatic hydrocarbons （PAHs） between two successive sediment suspensions

Successive sediment suspensions often happen in estuary, yet little research has probed into the difference in the release behaviors of organic compounds among different suspensions. This study took polycyclic aromatic hydrocarbons （PAHs） as typical organic contaminants and investigated the release behaviors between two successive suspensions with a particle entrainment simulator （PES）. Results showed that successive sediment suspensions lowered the concentration of dissolved PAHs in the overlying water via facilitating the re-adsorption of dissolved PAHs onto the suspended particles. Fast-release and slow-release periods of PAHs were successively observed in the both suspensions. The concentration changes of dissolved PAHs in the second suspension were generally similar with but hysteretic to those in the first suspension. More vigorous desorption and re-absorp- tion of PAHs were induced in the second suspension. Successive sediment suspensions obviously decreased the concentrations of mineral composition and organic matters in the overlying water, which significantly affects multi- phase distribution of PAHs.

Distinct community assembly processes underlie significant spatiotemporal dynamics of abundant and rare bacterioplankton in the Yangtze River

The rare microbial biosphere provides broad ecological services and resilience to various ecosystems.Nevertheless,the biogeographical patterns and assembly processes of rare bacterioplankton communities in large rivers remain uncertain.In this study,we investigated the biogeography and community assembly processes of abundant and rare bacterioplankton taxa in the Yangtze River(China)covering a distance of 4300 km.The results revealed similar spatiotemporal patterns of abundant taxa(AT)and rare taxa(RT)at both taxonomic and phylogenetic levels,and analysis of similarities revealed that RT was significantly influenced by season and landform than AT.Furthermore,RT correlated with more environmental factors than AT,whereas environmental and spatial factors explained a lower proportion of community shifts in RT than in AT.The steeper distance–decay slopes in AT indicated higher spatial turnover rates of abundant subcommunities than rare subcommunities.The null model revealed that both AT and RT were mainly governed by stochastic processes.However,dispersal limitation primarily governed the AT,whereas the undominated process accounted for a higher fraction of stochastic processes in RT.River flow and suspended solids mediated the balance between the stochastic and deterministic processes in RT.The spatiotemporal dynamics and assembly processes of total taxa were more similar as AT than RT.This study provides new insights into both significant spatiotemporal dynamics and inconsistent assembly processes of AT and RT in large rivers.

Bioaugmentation with a pyridine-degrading bacterium in a membrane bioreactor treating pharmaceutical wastewater

The bacterial strain Paracoccus denitrificans W12, which could utilize pyridine as its sole source of carbon and nitrogen, was added into a membrane bioreactor （MBR） to enhance the treatment of a pharmaceutical wastewater. The treatment efliciencies investigated showed that the removal of chemical oxygen demand, total nitrogen, and total phosphorus were similar between bioaugmented and non-bioaugmented MBRs, however, significant removal of pyridine was obtained in the bioaugmented reactor. When the hydraulic retention time was 60 hr and the influent concentration of pyridine was 250-500 mg/L, the mean effluent concentration of pyridine without adding W12 was 57.2 mg/L, while the pyridine was degraded to an average of 10.2 mg/L with addition of W12. The bacterial community structure of activated sludge during the bioaugmented treatment was analyzed using polymerase chain reaction-denaturing gradient gel electrophoresis （PCR-DGGE）. The results showed that the W12 inoculum reversed the decline of microbial community diversity, however, the similarity between bacterial community structure of the original sludge and that of the sludge after bioaugmentation decreased steadily during the wastewater treatment. Sequencing of the DNA recovered from DGGE gel indicated that sp., Sphingobium sp., Comamonas sp., and Hyphomicrobium sp. were the dominant organisms in time sequence in the bacterial community in the bioaugmented MBR. This implied that the bioaugmentation was affected by the adjustment of whole bacterial community structure in the inhospitable environment, rather than being due solely to the degradation performance of the bacterium added.

Microbial community changes in aquifer sediment microcosm for anaerobic anthracene biodegradation under methanogenic condition

The widespread distribution of polycyclic aromatic hydrocarbons （PAHs） in groundwater has become an important environmental issue. Knowledge of microbial community changes could aid in identification of particular microorganisms that are capable of degrading PAHs in contaminated aquifers. Therefore, 16S rRNA gene clone library analysis was used to identify the archaeal and bacterial communities in an aquifer sediment microcosm used for anaerobic anthracene degradation under methanogenic conditions. A remarkable shift of the archaeal community structure occurred after anaerobic anthracene degradation, but the types of the abundant bacterial phyla did not change. However, a decrease of both archaeal and bacterial diversity was observed. Bacterial genera Bacillus, Rhodococcus and Herbaspirillum might have links with anaerobic anthracene degradation, suggesting a role of microbial consortia. This work might add some new information for understanding the mechanism of PAH degradation under methanogenic conditions.

Biostability in distribution systems in one city in southern China: Characteristics, modeling and control strategy

This study investigated the bacterial regrowth in drinking water distribution systems receiving finished water from an advanced drinking water treatment plant in one city in southem China. Thirteen nodes in two water supply zones with different aged pipelines were selected to monitor water temperature, dissolved oxygen （DO）, chloramine residual, assimilable organic carbon （AOC）, and heterotrophic plate counts （HPC）. Regression and principal component analyses indicated that HPC had a strong correlation with chloramine residual. Based on Chick-Watson＇s Law and the Monod equation, biostability curves under different conditions were developed to achieve the goal of HPC 100 CFU/mL. The biostability curves could interpret the scenario under various AOC concentrations and predict the required chloramine residual concentration under the condition of high AOC level. The simulation was also carded out to predict the scenario with a stricter HPC goal （≤50 CFU/mL） and determine the required chloramine residual. The biological regrowth control strategy was assessed using biostability curve analysis. The results indicated that maintaining high chloramine residual concentration was the most practical way to achieve the goal of HPC ≤ 100 CFU/mL. Biostability curves could be a very useful tool for biostability control in distribution systems. This work could provide some new insights towards biostability control in real distribution systems.