Search

The distribution of antibiotic resistance genes (ARGs) derived from compost in soil–plant systems is a serious issue. One possible remedy is the application of biochar-containing compost. In this study, cucumber quality and the abundance of ARGs in soil–cucumber systems under different compost treatments, namely, traditional pig manure and corn straw compost (PC); pig manure, corn straw, and large particle size biochar (5–10 mm) compost (PCLB); and pig manure, corn straw, and small particle size biochar (

The impact of biochars with large particle sizes (LPB, 5-10 mm) and small particle sizes (SPB,0.074 mm) on fates of antibiotics and antibiotic resistance genes (ARGs) during composting of swine manure with maize straw was explored. The results showed that antibiotics removal efficiencies were 40 %, 50 %, and 76 % for control treatment, control with LPB treatment, and control with SPB treatment after composting, respectively. The introduction of SPB reduced the total ARGs and mobile genetic elements (MGEs) levels by 28 % and 19 % after composting, respectively. The Mantel test results showed that organic matter, moisture content, and NH

The efficient degradation of ciprofloxacin in tap and river water was investigated using the FeS2/PS system and the mechanism was studied. In addition, the tailwater after the reaction could be recycled to further reduce disposal costs.

The effect of pH regulation on schwertmannite bio-synthesis and its As removal ability were investigated in this study. The total Fe precipitation efficiency in a conventional schwertmannite bio-synthesis system (CK) reached 26.5%, with a mineral weight of 5.21 g/L and a mineral specific surface area of 3.18 m2/g. The total Fe precipitation efficiency increased to 88.4%-95.8%, the mineral weight increased to 17.10-18.62 g/L, and the specific surface area increased to 3.61-90.67 m2/g of five different treatments in which the system pH was continually adjusted to 2.50, 2.70, 2.90, 3.10, and 3.30 every 3 h, respectively. The very small amounts of schwertmannite were transformed to goethite when the system pH was periodically adjusted to 2.90, 3.10 and 3.30. The increased specific surface area of bio-schwertmannite was due to the contribution of mesopores, with most pores having a diameter of 2-20 nm. For actual As-containing groundwater (27.4 μg/L), the As removal rate was 52.9% for bio-schwertmannite collected from the CK system. However, the removal rate of As increased to 92.7%-97.8% for minerals which were collected after five adjusted pH treatments. The outcomes of this study provide a fresh insight into the bio-synthesis regulation of schwertmannite, and have great significance for the treatment of As-containing groundwater.

This paper took methyl orange (MO), a typical azo dye, as the target substance to explore the degradation mechanism of pyrite (FeS2)-activated persulfate (PS) by advanced oxidation technology, and response surface methodology was used to determine the optimal dosage of FeS2 and PS. The related experiments were conducted focused on different factors and degradation mechanisms. The results showed that when the initial concentration of MO was 0.1 mM, the pyrite was 1.6 g/L and PS was 1.0 mM, the degradation rate of MO could reach 92.94% in 150 min. In the FeS2/PS system, the main free radical was sulfate radical, which contributed about 22.43% to the degradation of MO, but the hydroxyl radical contributed little. Both pH ≤ 2 and pH ≥ 10 would have an inhibitory effect on the system, and the removal effect of MO was the best at initial pH of 4. The Cl−, HCO3− and H2PO4− might play an important role in the treatment of actual wastewater. This study had shown that HCO3− in a low concentration and Cl− had little effect on the system; H2PO4− and high concentration of HCO3− could inhibit the reaction of the system. By exploring the influence of different water matrices such as tap water, river water, and distilled water, it was found that HCO3− would have a negative impact on the experiment, and the degradation effect was obviously observed when the pH was adjusted to 4. The results can provide technical support for the degradation of pyrite-activated persulfate system in printing and dyeing wastewater.

A magnetic BiOCl/Fe3O4 catalyst with simulated solar light response was successfully prepared through a precipitation process and characterized by X-ray diffraction, scanning electron microscopy, UV–vis diffuse reflectance spectroscopy, VSM, Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy. The photocatalytic activity of BiOCl/Fe3O4 nanocomposites was further investigated through the photodegradation efficiency of carbamazepine (CBZ). In this study, 90.3% of CBZ was removed after 60 min irradiation in the presence of the BiOCl/Fe3O4 catalyst. Three reactive species were identified; the contribution of h+, HO , and O 2 - to CBZ degradation was approximately 94.98%, 3.25%, and 1.06%, respectively. The pH value had a significant effect on the CBZ degradation, and the best performance was achieved at pH 2.68. The presence of common anions (NO3−, Cl−, CO32−, and SO42−) also affected the CBZ degradation. The inhibiting effect followed the order of CO32− > SO42− > Cl−. However, NO3− weakly favored the photodegradation of CBZ. Moreover, the BiOCl/Fe3O4 photocatalyst could be easily recollected from the solution by applying an external magnetic field. This type of magnetic photocatalyst, which is characterized by ease of separation, may have application potential in wastewater treatment. The disappearance of CBZ as well as the formation of its products were determined by liquid chromatography mass spectroscopy and the possible photocatalytic degradation pathways were proposed.

Experiment and theoretical chemistry calculations were conducted to elucidate the mechanism of the reaction between 4-chlorobiphenyl (4-CB) and the NO3 radical. The degradation of PCBs was investigated mechanistically through transient absorption spectroscopy technology and high-accuracy theoretical calculation by using 4-CB as the model. Laser flash photolysis (LFP) experiments were performed at 355 nm. The main intermediate was analyzed through transient absorption spectroscopy and identified to be a charge transfer complex (CTC). The final products were identified through GC–MS analysis. The ground states and excited states of the reactants were calculated through density functional theory (DFT) method. The absorption bands at 400 and 700 nm show good agreement with the experimental results. The ratio of absorbance at 400 and 700 nm is 1.6, and the experimental value is 1.8. Analysis of the charge population indicated that one unit charge transfer from 4-CB to NO3. The entire reaction process was divid...

Degradation of OTC under different light with Fe2+/C2O42− was investigated, and the reaction mechanism was also discussed. Although Fe(II/III)-C2O42− complex could weaken the inhibitory effect of Fe(II/III)-OTC complex on the detection of OTC by HPLC, the acidification could make inhibition become minimal. Response surface methodology was used to optimize the Fe2+/C2O42− dosage at low concentrations of Fe2+ and H2C2O4. When the OTC concentration was 0.04 mM, the optimal dosage was OTC:Fe2+:H2C2O4 = 1:1.25:2 to attain a removal rate of 80% after 60 min under simulated solar light, and HO• for degradation of OTC with Fe2+/C2O42+ could be 53%, furthermore, removal rate of OTC just increased 3 percentage points at 60 min when the simulated solar light changed into UV-254 nm, however, OTC could also be degraded for 48.89% removal rate after 3 h illumination of simulated visible light. The influence of Cl−, CO32−, HCO3−, NO3−, NO2−, or H2PO4− on the degradation of OTC with Fe2+/C2O42− under simulated solar light was studied. NO2− could inhibit degradation for NO2− could react with free radicals, but the reason of inhibition of degradation by HCO3−, or CO32− was its influence on pH, whereas Cl−, NO3− and H2PO4− had no influence on degradation. In addition, when the concentration of CO32− was higher than 4 mM, CO32− could promote the degradation for the direct photolysis of OTC at alkaline (pH > 10). Four products were detected by LC-MS, and the OTC degradation pathway was discussed.

Acid mine drainage (AMD) is a serious environmental problem resulting from extensive sulfide mining activities. There is a lack of more comprehensive and detailed studies on the effect of AMD on calcareous soil characteristics and seed germination. In this study, five calcareous soil samples, collected from Xiaoyi, Taigu, Xiangning, Hejin, and Xixian counties in Shanxi Province, China, were used to investigate the effects of acid AMD on soil characteristics and Lolium perenne L. germination through laboratory culture experiments. The results showed that the increase in the total soil calcium oxide and magnesium oxide (CaO + MgO) contents led to a rise in the amount of Fe2+ in AMD converted into Fe3+, and that major ions (H+, Fe, SO42&minus, ) in AMD were trapped in the soil. The total Cao + MgO contents in the soil collected from Hejin and Taigu counties were 14.23% and 6.42%, the pH of AMD-polluted soil decreased to 7.24 and 3.10, and 98.7% and 54.0% of the Fe2+, 99.9% and 58.6% of the total Fe, and 76.0% and 26.4% of the SO42&minus, respectively, were trapped in the soil when the AMD volume to soil mass ratio was 10 mL/g. The results for the soil from Taigu County showed that when the soil had an AMD volume to soil mass ratio of 10 mL/g, the organic matter, available phosphorus (available P), available potassium (available K), Cr, and Cd contents in soil decreased by 16.2%, 63.0%, 97.1%, 7.8%, and 73.2%, respectively, the total phosphorus (total P) and total potassium (total K) did not significantly change, whereas the available nitrogen (available N) and total nitrogen (total N) increased to 16.1 times and 1.76 times, respectively. Compared to the initial soil collected from Taigu County, the Lolium perenne L. germination rate decreased by 81.1%, and the cumulative amount of Cr in the Lolium perenne L. increased by 7.24 times in the AMD-polluted soil when the AMD volume to soil mass ratio was 6 mL/g. The soil conditions could not support Lolium perenne L. germination when the AMD volume to soil mass ratio was 10 mL/g. The outcomes of this study could have important implication in understanding the hydrological/geochemical-behaviour of major ions of AMD in calcareous soil. The findings also have great significance in predicting plant growth behavior in AMD-polluted calcareous soil.

Degradation of OTC under simulated solar light with Fe2+/PS was investigated. Results showed the OTC–Fe(II or III) complex could disturb the detection of OTC by HPLC. However, acidification (pH

Degradation of OTC with Cu2+/PS under simulated solar light was investigated. Under simulated solar light or UV-254 light, metal ions could increase the degradation of OTC ( Mn2+ > Zn2+ > Cr3+ > Mg2+ ≈ Ca2+. When PS was used, the degradation of OTC under simulated solar light improved only with Cu2+. The optimum condition of OTC/Cu2+/PS under simulated solar light was OTC:Cu2+:PS = 1:1.5:1.75 and the removal rate of OTC could reach 93.5% after 1 h irradiation. In addition, the improvement of degradation of OTC with Cu2+/PS could also be found under UV-254 light or visible light, and the results showed that the energy of light could play an important role in the degradation of OTC. The mechanism of OTC/Cu2+/PS under light was discussed, and it could be that, under light irradiation, Cu2+ could change into Cu+ which could motive PS to produce SO4 −. The degradation of OTC with Cu2+/H2O2 under simulated light was studied to verify the mechanism. Moreover, The mineralization of OTC with Cu2+/PS under simulated solar light was analyzed. Furthermore, seven products were detected by LC-MS (EI+) and the OTC degradation pathway was discussed.

Research on coal desulfurization is very important for economic, social, and environmentally sustainable development. In this study, three batches of shake flask experiments were conducted for coal bio-desulfurization using Acidithiobacillus ferrooxidans to explore the relationship between microbial nutrients (iron-free M9 K medium) supply and coal bio-desulfurization efficiency. The results showed that the removal rates of pyritic sulfur and total sulfur from coal effectively increased following reintroduction of coal into the filtrate from previous batch. The removal rates of pyritic sulfur and total sulfur were 55.6% and 10.0%, 77.1% and 16.1%, and 86.5% and 28.2%, respectively, in the three batch experiments without iron-free M9 K medium addition. In contrast, the removal rates of pyritic sulfur and total sulfur reached 87.5% and 28.2%, 89.1% and 31.6%, and 92.0% and 29.1%, respectively, in the three batch experiments with 6.7% iron-free M9 K medium addition. However, addition of excessive iron-free M9 K medium was detrimental to coal bio-desulfurization because of the synthesis of jarosite (MFe3(SO4)2(OH)6, M = K+, NH4+) and gypsum (CaSO4·2H2O), which further declined the pyritic sulfur bio-oxidation efficiency and total sulfur removal efficiency.

Acid mine drainage (AMD) is a serious environmental problem resulting from extensive sulfide mining activities. There is a lack of more comprehensive and detailed studies on the effect of AMD on calcareous soil characteristics and seed germination. In this study, five calcareous soil samples, collected from Xiaoyi, Taigu, Xiangning, Hejin, and Xixian counties in Shanxi Province, China, were used to investigate the effects of acid AMD on soil characteristics and Lolium perenne L. germination through laboratory culture experiments. The results showed that the increase in the total soil calcium oxide and magnesium oxide (CaO + MgO) contents led to a rise in the amount of Fe2+ in AMD converted into Fe3+, and that major ions (H+, Fe, SO42−) in AMD were trapped in the soil. The total Cao + MgO contents in the soil collected from Hejin and Taigu counties were 14.23% and 6.42%, the pH of AMD-polluted soil decreased to 7.24 and 3.10, and 98.7% and 54.0% of the Fe2+, 99.9% and 58.6% of the total Fe, and 76.0% and 26.4% of the SO42−, respectively, were trapped in the soil when the AMD volume to soil mass ratio was 10 mL/g. The results for the soil from Taigu County showed that when the soil had an AMD volume to soil mass ratio of 10 mL/g, the organic matter, available phosphorus (available P), available potassium (available K), Cr, and Cd contents in soil decreased by 16.2%, 63.0%, 97.1%, 7.8%, and 73.2%, respectively; the total phosphorus (total P) and total potassium (total K) did not significantly change; whereas the available nitrogen (available N) and total nitrogen (total N) increased to 16.1 times and 1.76 times, respectively. Compared to the initial soil collected from Taigu County, the Lolium perenne L. germination rate decreased by 81.1%, and the cumulative amount of Cr in the Lolium perenne L. increased by 7.24 times in the AMD-polluted soil when the AMD volume to soil mass ratio was 6 mL/g. The soil conditions could not support Lolium perenne L. germination when the AMD volume to soil mass ratio was 10 mL/g. The outcomes of this study could have important implication in understanding the hydrological/geochemical-behaviour of major ions of AMD in calcareous soil. The findings also have great significance in predicting plant growth behavior in AMD-polluted calcareous soil.

This study evaluated the removal of chloramphenicol (CAP) by persulfate (PS) activated by Fe2+ and zerovalent iron (ZVI). Results showed that the Fe2+-PS system ineffectively degraded CAP. However, CAP oxidation accelerated as the number of Fe2+ portions added increased. Comparing with Fe2+, up to 96.1% of CAP was degraded when ZVI was employed as an alternative source of Fe2+. The ZVI-PS system was effective in a broader initial pH range from 3 to 10, and low pH promoted CAP degradation. In addition, the results of scavenging tests suggested that HO center dot, SO4- and O-2(center dot-) contributed to the overall degradation performance, but HO center dot predominated at all pH levels used. The rate of CAP removal slightly increased upon the addition of 1 mM Cl-, but adding Cl- at concentrations higher than 1 mM apparently inhibited CAP degradation. HCO3-, NO3-, NO2-, H2PO4-, HPO42-, and HA significantly inhibited CAP decomposition. Up to 92.8%, 94.7%, and 75.7% of CAP were removed from the filtrate, permeate, and retentate phases of wastewater, respectively. This result indicated that the ZVI-PS system can significantly remove CAP from wastewater and even concentrated wastewater. The intermediate products during oxidation were identified, and the degradation pathways of CAP were tentatively proposed. (C) 2015 Elsevier B.V. All rights reserved.

A magnetic BiOCl/Fe

BiOCl x I y nanospheres have been synthesised via precipitation method in ethylene glycol (EG)-water (H 2 O) mixed solvent at 80 °C and ambient pressure. Results of BiOCl x I y characterisation showed that these composite materials well combined BiOCl with BiOI crystals, which displayed flower-like hierarchical nanospheres consisted of numerous nanosheets and possessed smaller particle size, higher surface area than those in previous papers. The great surface area resulted in its high adsorption abilities of hydroxyphenylacetic acid (p-HPA) in the dark, the adsorption process could be suitably described by a pseudo-second-order kinetics model and the adsorption isotherms could be well fitted with Freundlich and Langmuir equations. The photocatalytic degradation of p-HPA and acetaminophen (ACTP) were investigated under simulated solar and visible irradiation using BiOCl x I y catalyst for the first time. The combination of BiOCl and BiOI to a certain extent has largely improved the remove efficiency, and BiOCl 0.75 I 0.25 was the optimal catalyst with almost 100% removal of p-HPA and 80% removal of ACTP under solar light for 3 h. Experimental results demonstrated that the photocatalytic degradation of p-HPA and ACTP followed pseudo-first-order kinetics and O 2 − and dissolved oxygen play predominant roles in photocatalytic process efficiency. This research will supply an environment-friendly photocatalyst for pharmaceutical wastewater treatment under sunlight.

Increased usage and discharge of sunscreens have led to ecological safety crisis, and people are developing the advanced oxidation processes (AOPs) to treat them. The present study aimed to determine the degradation efficiency and mechanism of the sunscreen agent p-aminobenzoic acid (PABA) using the UV/Fe(2+)/persulphate (PS) method. A series of irradiation experiments were conducted to optimise the system conditions and to study the impacts of the natural anion. Free radicals and degradation products were identified in order to clarify the degradation mechanism. Initial PS and Fe(2+) concentrations showed significant impacts on PABA degradation. Natural anions, such as Cl(-), NO3 (-), H2PO4 (-) and HCO3 (-), impeded PABA degradation because of ion (Fe(2+)) capture, radical scavenging or pH effects. Hydroxyl (HO·) and sulphate (SO4 (·-)) radicals were two main radicals observed in the UV/Fe(2+)/PS system; of these, SO4 (·-) showed greater effects on PABA degradation. Over 99 % of the available PABA was completely degraded into carbon dioxide (CO2) and water (H2O) by the UV/Fe(2+)/PS system, and the remaining PABA participated in complex radical reactions. By-products were identified by total ion chromatography and mass spectrometry. Our research provides a treatment process for PABA with high degradation efficiency and environmental safety and introduces a new strategy for sunscreen degradation.