Phosphate-Solubilizing Capacity of Paecilomyces lilacinus PSF7 and Optimization Using Response Surface Methodology.

Phosphorus-solubilizing microorganisms release organic acids that can chelate mineral ions or reduce the pH to solubilize insoluble phosphates for use by plants; it is important to study potential phosphorus-solubilizing microorganisms for use in agriculture. In this study, PSF7 was isolated from the soil of the Wengfu Phosphorus Tailings Dump in Fuquan City, Guizhou Province, China. PSF7 was identified as Paecilomyces lilacinus, based on morphological characterization and ITS sequencing analysis. The relationship between the phosphorus-solubilizing capacity and pH variation of PSF7 under liquid fermentation was studied. The results showed that there was a significant negative correlation (-0.784) between the soluble phosphorus content of PSF7 and the pH value. When PSF7 was placed under low phosphorus stress, eight organic acids were determined from fermentation broth using HPLC, of which tartaric acid and formic acid were the main organic acids. Different optimization parameters of medium components were analyzed using response surface methodology. The optimized medium components were 23.50 g/L sucrose, 1.64 g/L ammonium sulfate and soybean residue, 1.07 g/L inorganic salts, and 9.16 g/L tricalcium phosphate, with a predicted soluble phosphorus content of 123.89 mg/L. Under the optimum medium composition, the actual phosphorus-solubilizing content of PSF7 reached 122.17 mg/L. Moreover, scanning electron microscopy analysis of the sample was carried out to characterize the phosphate-solubilizing efficiency of PSF7 on mineral phosphate. The results provide useful information for the future application of PSF7 as a biological fertilizer.

Efficient decomposition of perfluorooctane sulfonate by electrochemical activation of peroxymonosulfate in aqueous solution: Efficacy, reaction mechanism, active sites, and application potential.

The electrochemical oxidation method is a promising technology for the degradation of perfluorooctane sulfonate (PFOS). However, the elimination processes of PFOS are still unknown, including the electron transfer pathway, key reactive sites, and degradation mechanism. Here, we fabricated diatomite and cerium (Ce) co-modified Sb2O3 (D-Ce/Sb2O3) anode to realize efficient degradation of PFOS via peroxymonosulfate (PMS) activation. The transferred electron and the generated hydroxyl radical (•OH) can high-effectively decompose PFOS. The electron can be rapidly transferred from the highest occupied molecular orbital of the PFOS to the lowest unoccupied molecular orbital of the PMS via the D-Ce/Sb2O3 driven by a potential energy difference under electrochemical process. The active site of Ce-O in the D-Ce/Sb2O3 can greatly reduce the migration distance of the electron and the •OH, and thus improving the catalytic activity for degrading various organic micropollutants with high stability. In addition, the electrochemical process shows strong resistance and tolerance to the changing pH, inorganic ions, and organic matter. This study offers insights into the electron transfer pathway and PMS activation mechanism in PFOS removal via electrochemical oxidation, paving the way for its potential application in water purification.

Exploration of perfluorooctane sulfonate degradation properties and mechanism via electron-transfer dominated radical process.

Polyfluoroalkyl and perfluoroalkyl chemicals (PFCs) widely used in lubricants, surfactant, textiles, paper coatings, cosmetics, and fire-fighting foams can release a large deal of organics contaminants into wastewater and pose great risks to the health of humans and eco-environments. Although advanced oxidation processes can effectively deconstruct various organic contaminants via reactive radicals, the stable structure of PFCs makes it difficult to be degraded. Here, we confirm that electrochemical oxidation process coupled with peroxymonosulfate (PMS) reaction can efficiently destroy stable structure of PFCs via electron transfer and meanwhile completely degrade PFCs via generated active radicals. We further studies via capturing and scavenging radicals, and DFT calculations find that electron hydroxyl radials play a dominant role in degrading PFCs. Based on the calculations of adsorption energy and molecular orbital energy we further demonstrate that many active sites on the surface of Ti4O7 (1 0 4) plane can rapidly take part in electrochemical reaction for generating radials and removing organic contaminants. These results give a promising insight towards high-effective and deep degradation of PFCs via electrochemical reaction coupled with advanced oxidation processes, as well as providing guidance and technical support for the remove of multiple organic contaminants.

Exploring key reaction sites and deep degradation mechanism of perfluorooctane sulfonate via peroxymonosulfate activation under electrocoagulation process.

Perfluorooctane sulfonate (PFOS), normally present in groundwater and surface water, is an emerging environmental contaminants, but is extremely difficult to be degraded due to high energy of the C-F bond. Here, an electrocoagulation (EC) technique coupled with peroxymonosulfate (PMS) activation was used to deeply degrade PFOS. Results showed that approximately 100% PFOS was removed from the solution in the monopolar serial (MS) mode within 60 min and achieved a high kinetic rate of 0.074 min-1, which was significantly higher than those of reported studies (Table S3). Energy consumption (2.06 kWh/kg) in the MS mode was significantly lower than that of Al (52.30 kWh/kg) and Zn (213.50 kWh/kg) electrodes, which further confirmed the potential application prospects of EC technique. The quenching experiments, electron spin response (ESR) analysis, and DFT calculations can verify that ·OH was the main radical from the reaction of Fe2+-OH reaction site with PMS. In addition, results from fluorine balance and TOC removal also indicated the complete mineralization and degradation of PFOS in the EC process. Quantum chemical calculations can confirm the PFOS degradation mechanism and key active sites for direct electron transfer and radical attack. After five cycle operations of PFOS degradation, the EC process was still effective in degrading PFOS with a removal efficiency above 98%. Thus, this work provided a novel alternative for the high-effective treatment of PFOS from contaminated environmental water bodies.

Spraying carbon powder derived from mango wood biomass as high-performance anode in bio-electrochemical system.

Microbial fuel cell is a green and sustainable bio-electrochemical system that can harvest bioelectricity from organic matter conversion by bacteria in wastewater, but weak electrochemical activity and poor biocompatibility between electro-active bacteria and anode limit its scale-up application. In the present, the biomass carbon derived from mango wood was prepared via one-step carbonization method for anode materials in microbial fuel cell. A desirable anode C/1050 with large electrochemical active surface area (75.3 cm2), low electron transfer resistance (4.36 Ω), and benign biocompatibility were developed, achieving power density up to 589.8 mW·m-2. This study provides a low-cost and high-performance biomass carbon used as anode material in microbial fuel cell for practical application.

Improved cathodic oxygen reduction and bioelectricity generation of electrochemical reactor based on reduced graphene oxide decorated with titanium-based composites.

A kind of reduced graphene oxide decorated with titanium-based (RGO/TiO2) composites are successfully synthesized and employed in this current study as a novel nonprecious metal catalyst for enhancing bioelectricity generation and cathodic oxygen reduction reaction (ORR) in single chamber microbial fuel cells (MFCs). Compared with commercial Pt/C, RGO/TiO2 shows obviously enhanced oxygen reduction reaction activity due to the appropriately-permeated, large electrochemical active area, enough exposure of electrocatalytic active sites of RGO/TiO2. The air-cathode MFC with RGO/TiO2-1 cathode achieves 1786.7 mW m-3 of power density, 86.7% ±â€¯1.2% of COD removal and 31.6% ±â€¯1.1% of CE, which are higher than commercial Pt/C. Moreover, RGO/TiO2-1 cathode exhibits high-effective electrocatalytic activity, and the power density of RGO/TiO2-1 can keep a stable level and only has a minor decline (5.35%) during 30-cycles operation. These results indicate that RGO/TiO2-1 is a potential cathode catalyst, markedly enhancing cathode ORR, wastewater treatment efficiency, and bioelectricity generation of MFC.

[ANAMMOX Reactor with Two Kinds of Inoculated Sludge: Start-up and Kinetics Characteristics].

Two different mixed sludges (aerobic nitrifying sludge and ANAMMOX-denitrification sludge:R1, and anaerobic digestion flocculent sludge and ANAMMOX-denitrification sludge:R2), were used as inocula in two UBF reactors to enrich Anammox bacteria. Both kinds of mixed sludge set up the Anammox process successfully. It took 36 days for R1, while R2 required 53 days. Nitrogen removal rates of R1 and R2 were high during the whole operation. During the stable operation stage, the removal rates of NH4+-N, NO2--N, and TN were about 99.92%, 96.64%, and 81.87% for R1; and 97.54%, 94.91%, and 80.98% for R2. Illumina High-throughput Sequencing revealed Candidatus Kuenenia was in the top six taxa in the two reactors with 3.22% relative abundance in R1 and 2.35% in R2 after the successful start-up. Simulation results indicated that the Modified Stover-Kincannon model and the second-order model were appropriate models. It was deduced that the N-removal potential of R1 was a little greater than that of R2 after comparing the projected maximum substrate removal rate Umax of the two reactors.

[Adsorption Performance and Mechanism of HZO@SGH for the Removal of Fluoride from Aqueous Solution].

Three-dimensional porous composites based on hydrous zirconium oxide and self-assembled graphene hydrogels (HZO@SGH) were successfully synthesized via homogeneous precipitation. HZO@SGH was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) to investigate the morphology and the defluoridation mechanism. The adsorption performance and mechanism of HZO@SGH for fluoride was investigated via batch adsorption experiments. The results revealed that the adsorption capacity of HZO@SGH for fluoride was obviously higher than that of HZO or SGH singly. The adsorption data for fluoride onto HZO@SGH complied with the pseudo-second-order kinetic model, indicating that the adsorption rate was mainly controlled by chemical adsorption. The adsorption process could be described well with the Dubinin-Radushkevich isotherm model, as the maximum adsorption capacity was approximately 31.79 mg·g-1, which is higher than that of some zirconium-containing adsorbents, as previously reported. HZO@SGH showed excellent adsorption properties in the fluoride solution contained NO3-, Cl-, and a low concentration of SO42- (≤ 10 mg·L-1) at low pH (3-6.5). The preparation of HZO@SGH was convenient and environmentally friendly, as it was easily separated from the fluoride solution and did not cause secondary pollution. Hence, the prospect of HZO@SGH in practice was brilliant.

[Preparation of PAAm/HACC Semi-Interpenetrate Network Hydrogel and Its Adsorption Properties for Humic Acid from Aqueous Solution].

New absorbents, polyacrylamide/chitosan quaternary ammonium salt semi-interpenetrate network hydrogels[(PAAm/HACC semi-IPN), (s-IPN 1.5), and (s-IPN 3)], were successfully prepared via in situ polymerization by thermal synthesis for the removal of humic acid (HA) from aqueous solution. The materials were characterized by SEM, FT-IR, and XRD. The adsorption behaviors of adsorbents for HA were investigated as a function of pH, ionic strength, contact time, initial HA concentration, and temperature. The results showed that s-IPN 3 outperformed s-IPN 1.5. The adsorption capacity of the adsorbent for HA decreased with an increase in solution pH and decrease of temperature, and low ionic strength was conducive to the adsorption of HA. The adsorption kinetics fitted to a pseudo-second-order kinetic model and the adsorption isotherms could be described by the Sips isotherm model. The impressive maximum adsorption capacity could reach 238.08 mg·g-1 at the condition of pH=7.0, ionic strength=0.01 mol·L-1, and T=298 K. The adsorbent could remove HA from aqueous solution efficiently.

Antioxidative responses of Pseudomonas fluorescens YZ2 to simultaneous exposure of Zn and Cefradine.

Binary pollution of both heavy metals and antibiotics has received increasing attentions for their joint effects of eco-toxicity and health hazards. To reveal the effects of mixtures of different pollutants on bacterial antioxidant response system, Pseudomonas fluorescens ZY2, a new strain isolated from swine wastewater, was chosen to determinate growth (bacterial density OD600), reactive oxygen species (ROS) concentration, protein concentration and superoxide dismutase (SOD) activity under exposure treatments of Zn, Cefradine or Zn + Cefradine. Bacterial densities of all the treatment groups increased significantly over the incubation time, but those containing pollutant addition were slightly lower than the control at different times of incubation. Both ROS concentration and SOD activity increased first and then decreased (p < 0.01) over time, which was opposite to the protein concentrations (p < 0.01), showing a much significant increase by Cefradine alone. With Zn concentration increasing from 40 to 160 mg/L, the intracellular SOD activity increased as a response to the improvement of ROS (p < 0.05), while the balance between ROS and SOD was broken down due to the disproportionate change of total SOD activity and ROS concentration, the bacterial densities therefore decreased for the weak resistance. With the combined treatment of Zn (200 mg/L) and Cefradine (1 mg/L), though the toxicity of Zn caused a much significant increase of ROS, the bacterial resistance was further improved showing a more significant increase of total SOD activity and the bacterial densities therefore increased bacterial growth. Zn concentration also affected the protein synthesis. Either single or binary stress induced the bacterial resistance by regulating SOD activity to eliminate ROS. All results of the bacterial oxidant stress, SOD response and protein synthesis in the combined treatment groups were more complicated than those in single treatment groups, which depended on the properties of the single treatment as well as the interaction between the two treatments upon bacterial activity. For P. fluorescens ZY2, the mediation of SOD activity to eliminate ROS in response to the combined exposure to Zn and Cefradine was first revealed as one of the co-resistance mechanisms, which is informative to further understanding the risk of antibiotics resistant bacteria to human and environmental health more accurately.

Size distribution and leaching characteristics of poly brominated diphenyl ethers (PBDEs) in the bottom ashes of municipal solid waste incinerators.

The particle size distributions and leaching characteristics of polybrominated diphenyl ethers (PBDEs) in the bottom ashes of two Taiwanese municipal solid waste incinerators (MSWIs A and B) were investigated to evaluate PBDE leaching into the environment through reutilization of bottom ashes. The PBDE contents in the bottom ashes of the MSWIs (29.0-243 ng/g) could be two orders higher than those in rural and urban soils. The PBDE fraction of the bottom ashes was more distributed in larger particles (> 0.25 mm). Similar trends were found for the PBDE contents in the bottom ashes and their PBDE leaching concentrations, revealing that the elevated PBDE contents in the bottom ashes may lead to a higher PBDE leaching mass. The leaching of PBDEs is attributed to diffusion driven by the concentration gradient and effective surface area. The normalized leaching ratios (NLRs) of PBDEs for the bottom ashes of the MSWIs are about four orders greater than those of PBDE-related raw materials and products, and this may be due to their porous structures having much greater effective surface area. The elevated NLRs of PBDEs thus deserve more attention when bottom ashes are recycled and reutilized as construction materials.

[Leaching kinetics of josephinite tailings with sulfuric acid].

Leaching is the most important step of josephinite tailing recycle technology. This step can separate the valuable metal Mg from Si and other impure metal. Effects of sulfuric acid on leaching Mg efficiency from josephinite tailings were investigated. To obtain the leaching behavior, a modified unreacted shrinking core model that based on the experimental data was used to determine the dissolution kinetic parameters. The model was significant and showed that the dissolution of Mg2+ in josephinite tailing was controlled by the produce layer diffusion, apparent activation reaction energy E = 34.04 kJ x mol(-1). The produce layers obstruct the forward reaction of the dissolution of Mg2+.

[Degradation kinetics of activated carbon catalyzed persulfate oxidation orange G].

The oxidation degradation of orange G (OG) in aqueous solutions by the activated carbon catalyzed peroxydisulfate (PDS) has been kinetically investigated. These processes are based on the generation of sulfate radicals, which are powerful oxidizing species found in nature. The results demonstrated that OG could be degraded by GAC/PDS reagent effectively. Moreover, the dosage of PDS and GAC, temperature and initial concentration of OG had an impact on OG oxidation, higher temperature and GAC dosage resulted in higher OG degrading rates. In addition, the empirical kinetic equation for OG oxidation by GAC/PDS combined system under the conditions of 0.050-0.125 mmol x L(-1) of OG, 5.0 of pH, 10/1-160/1 of n(PDS)/n(OG), 0.1-1.6 g x L(-1) of GAC, 298-338 K of temperature, could be reasonably represented by the first order kinetics, which was fitted very well with the experimental data. In addition, the catalytic properties of reused GAC have been investigated.

[Study on kinetics of photoelectrocatalytic degradation of supported TiO2 on malachite green].

La-N co-doped TiO2 photocatalyst was synthesized by a sol-gel method, which used tetrabutyl titanate (TBOT) as the Ti resource, lanthanum nitrate as the La resource and urea as the N resource. The performance in the photocatalytic oxidation degradation of malachite green was investigated. The results showed that the reaction could be reasonably represented by first order kinetics, and a kinetic model was established; the reaction order of voltage (0.935 8) was higher than that of pH (0.6119) and that of initial concentration (0.335), indicating that voltage has the greatest impact on the reaction. The model data fitted well with experimental data (R2 0.910-0.9961), which indicates that the kinetic model can well describe the process of photocatalytic degradation of malachite green.

[Photoelectrocatalytic degradation kinetics of malachite green by Pr-N co-doped TiO2 photocatalyst].

Malachite green oxidation degradation was kinetically investigated in a photoelectrocatalytic reactor, using Pr-N co-doped TiO2 photocatalyst as the electrode which was prepared by a sol-gel method. The result shows that the initial concentration, pH, voltage and temperature had a significant impact on the oxidation rate. The kinetic equation for malachite green oxidation under the conditions of 10-30 mg x L(-1) of initial concentration, 3-8 of pH, 1-5 V of voltage, 298-338 K of temperature could be described using the first order kinetics, which was fitted well with the experimental data. The lower activation energy of 11.99 kJ x mol(-1) shows the reaction can be initiated easily; The reaction order of pH (1.634 7) is higher than that of voltage (0.850 2) and initial concentration (0.123 8), which indicates that the oxidation rate can be controlled efficiently through adjusted pH.

[Degradation kinetics of ozone oxidation on high concentration of humic substances].

Humic substance oxidation (HS) degradation by ozone was kinetically investigated. The effects of O3 dosage, initial pH, temperature and initial concentration of HS were studied. Under the conditions of 3.46 g x h(-1) ozone dosage, 1 000 mg x L(-1) initial HS, 8.0 initial pH and 303 K temperature, the removal efficiencies of HS achieved 89.04% at 30 min. The empirical kinetic equation of ozonation degradation for landfill leachate under the conditions of 1.52-6.10 g x h(-1) ozone dosage, 250-1 000 mg x L(-1) initial HS, 2.0-10.0 initial pH, 283-323 K temperature fitted well with the experimental data (average relative error is 7.62%), with low activation energy E(a) = 1.43 x 10(4)J x mol(-1).

[Utilizing the wastewater treatment plant sludge for the production of eco-cement].

The aim of this paper was to study the effect on cement property by using of municipal sewage as additive in the process of clinker burning. Based on the standard sample P. 042. 5 from cement plant, the properties of eco-cement samples adding municipal sewage to unit raw material by 0%, 0.50%, 1.00%, 1.50%, 2.00%, 2.50% respectively and the standard sample from the cement plant were compared. According to the analysis of X-ray diffraction, microstructure, the particles size determination material change, the setting time, specific surface area, leaching toxicity and strength of cement mortar of the cement, respectively, it showed that the strength of the productions were similar to the P. 042.5 standard sample. The metal ion concentrations of Al, Fe, Ba, Mn and Ti in clinkers and raw material decreased, the initial and setting time increased, as well as the strength of the paste within the curing time of 3 days decreased with the increase of municipal sewage ratio. However, after the curing of 7 days, the strength was similar to non-sludge-mortar or even higher.

[Degradation kinetics of ozone oxidation on landfill leachate rejected by RO treatment].

This study kinetically investigated landfill leachate rejected by reverse osmosis (RO) oxidation degradation by ozonation. Initial pH, ozone dosage, temperature and initial COD had significant impact on the oxidation rate. The results demonstrated that for the removal efficiencies of COD 67.6% under the conditions of 8.0 pH, 5.02 g/h ozone dosage, 303K temperature. The empirical kinetic equation of ozonation degradation for landfill leachate under the conditions of 2.0-8.0 pH, 2.53-6.90 g/h ozone dosage, 934-4 037 mg/L initial COD, 283-323 K temperature fitted well with the experimental data(R2 0.969-0.996), with low activation energy E(a) = 1.43 x1094) J x mol(-1).

[Kinetics of humic substances oxidation degradation by Fenton's reagent].

Humic substances (HS) oxidation degradation by Fenton's reagent was kinetically investigated in this study. HS was removed by both oxidation and coagulation during Fenton treatment. Moreover, initial pH, the dosage of Fenton's reagent and initial concentration of HS had a significant impact on HS oxidation rate and the oxidation mainly occurred at the first 60 min of reaction time. The empirical kinetic equation for HS oxidation by Fenton's reagent under the conditions of 308 K of temperature, 4.0 of pH, 5-40 mmol x L(-1) of Fe2+, 40-120 mmol x L(-1) of H2O2, 250-1 000 mg x L(-1) of HS, could be described using a kinetic model, which was fitted very well with the experimental data. The overall reaction order is 2.34. The lower activation energy of 14.9 kJ x mol(-1) shows that Fenton reaction can be initiated easily. The reaction order of H2O2 (0.86) is higher than that of Fe2+ (0.47), which indicates that the effect of initial H2O2 concentration is greater than that of Fe2+ on the oxidation degradation of HS by Fenton process.

[Removal of humic acids by oxidation and coagulation during Fenton treatment].

Simulated high concentration humic acids (HA) wastewater was treated by Fenton process. The influence of reaction time, initial pH, H2O2 and Fe2+ dosage on the reduction results of COD, TOC, UV254, A400 are presented. The changes of mean oxidation state (eta), A465/A665, the ratio of COD removal by oxidation to that by coagulation (phi) and Zeta potential (zeta) were used to evaluate the roles of oxidation and coagulation in reducing HA during Fenton treatment. The results demonstrate that Fenton's reagent can effectively degrade HA under a wide initial pH range (2.0-5.0), simultaneously the absorbance decrease in 400 nm was higher (from 78.2% to 94.5%) than that in 254 nm (from 75.6% to 88.4%) and the COD removal (from 50.8% to 62.5%) is higher than TOC removal (from 31.2% to 35.1%) in 2 h reaction time. The amount of HA is removed by both oxidation and coagulation. Oxidation played a primary role in removal of HA at the beginning of Fenton reaction. The large molecular weight component of HA appears to be easily degraded and the formations of low molecular persistent organic intermediate compounds are difficult to be mineralized. The COD removal efficiency by oxidation decreases over the ferrous dosage of 0.08 mol/L. Furthermore, the results reveal that HA removal by coagulation was reduced mainly by charge neutralization as well as adsorption bridge building. Results highlight the role of oxidation in controlling the efficiency of COD removal by coagulation, so high COD(oxid) may cause relatively low COD(coag). Meanwhile, ferrous dosage greatly influences COD removal by coagulation at high peroxide dosages over 0.2 mol/L.