A novel simultaneous short-course nitrification, denitrification and fermentation process: bio-enhanced phenol degradation and denitrification in a single reactor.

The feasibility of a simultaneous nitrification, denitrification and fermentation process (SNDF) under electric stirrer agitation conditions was verified in a single reactor. Enhanced activated sludge for phenol degradation and denitrification in pharmaceutical phenol-containing wastewater under low dissolved oxygen conditions, additional inoculation with Comamonas sp. BGH and optimisation of co-metabolites were investigated. At a hydraulic residence time (HRT) of 28 h, 15 mg/L of substrate as strain BGH co-metabolised substrate degraded 650 ± 50 mg/L phenol almost completely and was accompanied by an incremental increase in the quantity of strain BGH. Strain BGH showed enhanced phenol degradation. Under trisodium citrate co-metabolism, strain BGH combined with activated sludge treated phenol wastewater and degraded NO2--N from 50 ± 5 to 0 mg/L in only 7 h. The removal efficiency of this group for phenol, chemical oxygen demand (COD) and TN was 99.67%, 90.25% and 98.71%, respectively, at an HRT of 32 h. The bioaugmentation effect not only promotes the degradation of pollutants, but also increases the abundance of dominant bacteria in activated sludge. Illumina MiSeq sequencing research showed that strain BGH promoted the growth of dominant genera (Acidaminobacter, Raineyella, Pseudarcobacter) and increased their relative abundance in the activated sludge system. These genera are resistant to toxicity and organic matter degradation. This paper provides some reference for the activated sludge to degrade high phenol pharmaceutical wastewater under the action of biological enhancement.

Higher Toxicity of Gaseous Organics Relative to Particulate Matters Emitted from Typical Cooking Processes.

Cooking emission is known to be a significant anthropogenic source of air pollution in urban areas, but its toxicities are still unclear. This study addressed the toxicities of fine particulate matter (PM2.5) and gaseous organics by combining chemical fingerprinting analysis with cellular assessments. The cytotoxicity and reactive oxygen species activity of gaseous organics were ∼1.9 and ∼8.3 times higher than those of PM2.5, respectively. Moreover, these values of per unit mass PM2.5 were ∼7.1 and ∼15.7 times higher than those collected from ambient air in Shanghai. The total oleic acid equivalent quantities for carcinogenic and toxic respiratory effects of gaseous organics, as estimated using predictive models based on quantitative structure-property relationships, were 1686 ± 803 and 430 ± 176 µg/mg PM2.5, respectively. Both predicted toxicities were higher than those of particulate organics, consistent with cellular assessment. These health risks are primarily attributed to the high relative content and toxic equivalency factor of the organic compounds present in the gas phase, including 7,9-di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione, 2-ethylhexanoic acid, and 2-phenoxyethoxybenzene. Furthermore, these compounds and fatty acids were identified as prominent chemical markers of cooking-related emissions. The obtained results highlight the importance of control measures for cooking-emitted gaseous organics to reduce the personal exposure risks.

Chemical Fingerprinting of HULIS in Particulate Matters Emitted from Residential Coal and Biomass Combustion.

Identification of humic-like substances (HULIS) structures and components is still a major challenge owing to their chemical complexity. This study first employed a complementary method with the combination of two-dimensional gas chromatography-time-of-flight mass spectrometry and liquid chromatography-quadrupole-time-of-flight mass spectrometry to address low-polarity and polar components of HULIS in PM2.5 (particulate matter with an aerodynamic diameter less than 2.5 µm), respectively. The combination method showed a significant correlation in identifying overlapping species and performed well in uncovering the chemical complexity of HULIS. A total of 1246 compound species in HULIS (65.6-81.0% for each sample), approximately 1 order of magnitude more compounds than that reported in previous studies, were addressed in PM2.5 collected in real-world household biomass and coal combustion. Aromatics were the most abundant compounds (37.4-64.1% in biomass and 34.5-70.0% in coal samples) of the total mass in all HULIS samples according to carbon skeleton determination, while the major components included phenols (2.6-21.1%), ketones (6.0-17.1%), aldehydes (1.1-6.8%), esters (2.9-20.0%), amines/amides (3.2-8.5%), alcohols (3.8-17.0%), and acids (4.7-15.1%). Among the identified HULIS species, 11-36% mass in biomass and 11-41% in coal were chromophores, while another 22-35 and 23-29% mass were chromophore precursors, respectively. The combination method shows promise for uncovering HULIS fingerprinting.

Characterization of phosphate solubilizing bacteria isolated from heavy metal contaminated soils and their potential for lead immobilization.

Phosphate solubilizing bacteria (PSB) were isolated from heavy metal contaminated soils and their potentials for lead (Pb) immobilization in soil were studied in this paper. 53 PSB strains were isolated and their minimum inhibitory concentrations (MICs) for lead were determined. The results showed that strains B3, B4, B10, F2-1 and L1-5 had relatively high lead resistant capabilities with MICs ranged from 0.5 to 8 mM, and were identified as species of Leclercia adecarboxylata and Pseudomonas putida by 16S rRNA. The most efficient PSB strains could solubilize 200 mg L-1 of P, and phosphate solubilizing capacity of those PSBs was related to the concentrations of organic acids, acid phosphatase activity and pH. Furthermore, the growth pattern of L1-5 strain with the presence of Pb(NO3)2 was observed and a mechanism of biomineralization of lead ions in bacteria biomass was determined by FT-IR and XRD analyses. Results showed that high concentration of lead can inhibit the growth of PSBs, and L1-5 isolate can transform lead ions into lead hydroxyapatite and pyromorphite. The PSBs, which possessing the properties of immobilizing lead through phosphate solubilization and biomineralization could be exploited for bioremediation of Pb polluted soils in future.

Condensable and filterable particulate matter emitted from typical diesel vehicles in steady and transient driving conditions.

Condensable particulate matter (CPM) and filterable particulate matter (FPM) emitted from industrial sources have been well studied, but their emissions from vehicles have not yet been covered. This study explores the emission characteristics of CPM and FPM from typical diesel vehicles under various driving conditions. The emission factors (EFs) of CPMs under driving conditions were 5.4-10.4 times higher than those of FPMs, while CPMs EFs under transient driving conditions were about 2.5 times higher than those under steady driving conditions. CPM and FPM are mainly composed of organic matter accounting for 53.3 %-92.9 %, while the intermediate and semi-volatile organic compounds dominate the organic matter accounting for 86.3 %-98.6 %. Similar to industrial sources, alkanes are the predominant organic species emitted by diesel vehicles, comprising 42.0 %-64.0 % of the detected organic components. Inorganic CPM is primarily composed of NH4+ , representing 84.9 %-87.6 % of the total, in contrast to industrial sources where SO42- and Cl- dominate. Interestingly, the air pollution control devices installed on diesel vehicles under steady driving conditions perform better in removing organic CPM and producing higher inorganic CPM emissions than those under transient driving conditions. These findings will enhance the comprehensive understanding of particulate matter emitted from diesel vehicles and provide a scientific foundation for the development of related control technologies.

An online technology for effectively monitoring inorganic condensable particulate matter emitted from industrial plants.

The concentration of condensable particulate matter (CPM) has gradually exceeded that of filterable particulate matter emitted from industrial plants equipped with advanced air pollution control systems. However, there is still no available online technology to measure CPM emissions. Based on the significant linear correlations (R2 > 0.87, p < 3 × 10-3) between the electrical conductivity (EC) values and ionic mass concentrations of the CPM solutions when the interference of H+ was excluded. We developed an online inorganic CPM monitoring system, including a cooling and condensation unit, pH and EC meters, a self-cleaning unit, and an automatic control unit. The CPM mass concentrations obtained by the developed online monitoring system agree well (mean bias 3.8-20.7%) with those obtained by the offline system according to USEPA Method 202 when used in parallel during real-world studies. Furthermore, individual ion mass concentrations of CPMs can even be retrieved separately with a time resolution of one hour when industrial plants are under steady operating conditions. The newly developed system makes the online monitoring of CPM emissions available and lays a foundation for the control of CPM emitted from industrial sources to further improve air quality.

Enhanced passivation of lead with immobilized phosphate solubilizing bacteria beads loaded with biochar/ nanoscale zero valent iron composite.

Phosphate solubilizing bacteria (PSBs) can effectively enhance the stability of lead via the formation of insoluble Pb-phosphate compounds. This research presents a bio-beads, which was implemented with the help of a self-designed porous spheres carrier, by immobilized PSBs strains Leclercia adecarboxylata (hereafter referred as L1-5). In addition, the passivation efficiency of lead via bio-beads under different conditions and its mechanism were also investigated in this study. The results indicated that phosphate solubilized by bio-beads could reach 30 mg/L in Ca3(PO4)2 medium containing 1 mM Pb2+, and the highest removal rate of Pb2+ in beef peptone liquid medium could reach 93%, which is better than that of free bacteria. Furthermore, it was also concluded that the lead could be transformed into stable crystal texture, such as Pb5(PO4)3Cl and Pb5(PO4)3OH. Both hydrophobic and hydrophilic groups in the bio-beads could capture Pb2+, which indicated that electrostatic attraction and ion-exchange were also the mechanism of Pb2+ adsorption. All the experimental findings demonstrated that this bio-bead could be consider as an efficient way for the lead immobilization in contaminated soil in the future.

Way forward for straw burning pollution research: a bibliometric analysis during 1972-2016.

Straw burning has become a hot topic in recent years as it poses a great risk not only to the lung health of residents in exposed areas but also to large-scale haze events. In order to have a more comprehensive understanding of straw burning research, based on the bibliometric analysis of Science Citation Index Expanded from Web of Science, the research progress of straw burning pollution from 1972 to 2016 and the future research trends were carried out in this paper. The research focuses on the document type, language, publication year, times cited and its output characteristics, subject category, journal, national and institutional distribution, author, etc. The results show that the study of straw burning pollution has shown a significant increase over the past 45 years. A total of 813 publications were found, and English was the most commonly used language. Articles were the most frequently appeared document types, and the researches were strongly embracing with the top 3 popular subject categories of "environmental sciences and ecology," "agriculture," and "meteorology and atmospheric sciences." We identified that the major journals publishing straw burning pollution research were Atmospheric Environment, followed by Atmospheric Chemistry and Physics. China as a leader in paper quantity played an important role in the research field of straw burning pollution, while the USA and India were located in the second and third positions. The most productive institution was Chinese Academy of Sciences, followed by Peking University and University Arkansas. Based on our analysis and the consideration of current environmental problems, more studies should focus on the following three aspects in the future: driving mechanism of emission characteristics, construction of high-resolution emission inventories, and the influencing mechanism of straw burning pollutants on climate change and human health. Our analysis and prospects can be served as a useful reference for future studies.

Effects of Pb(II) and Cr(VI) Stress on Phosphate-Solubilizing Bacteria (Bacillus sp. Strain MRP-3): Oxidative Stress and Bioaccumulation Potential.

The aim of this work was to ascertain the effects of Pb(II) and Cr(VI) on bacterial growth, generation of reactive oxygen species (ROS), activities of superoxide dismutase (SOD), and catalase (CAT), as well as the localization of bioaccumulated heavy metals in a phosphate-solubilizing bacterium. The results showed that the ROS increased from 1.4-fold to 1.8-fold of control under Pb(II) stress and decreased from 1.6-fold to 1.1-fold of control under Cr(VI) stress corresponding to metal concentrations (0.5-5 mmol·L-1). The SOD activities were ROS dependent; however, the CAT activities increased under both Pb(II) and Cr(VI) stress, from 11.4 to 21.8 U·mg-1 and 11.4 to 32.9 U·mg-1, respectively. Intra/extracellular accumulation were investigated by scanning transmission electron microscopy with energy dispersive X-ray spectroscopy (STEM-EDS) and it was calculated that extracellular accumulated Pb accounted for 61.7-95.9% of the total accumulation, while extracellular accumulated Cr only accounted for up to 3.6% of the total accumulation. Attenuated total reflection/Fourier-transform infrared spectroscopy (ATR-FTIR) analysis confirmed that the functional groups involved in those extracellular accumulation were not located in the loosely bound extracellular polysaccharides substances.