Search

In recent years, the oil pollution problem on the Loess Plateau in western China is becoming increasingly serious, therefore, the use of hydroxyl radical (·OH) advanced oxidation process has increased due to its ability to efficiently degrade total petroleum hydrocarbon (TPH) in soil. However, the ability to produce ·OH of different oxidants varies widely, and the removal effect of specific pollutants has fluctuations and differences. The objective of this study is to screen the best oxidant according to the physico‐chemical properties and pollution situation of polluted soil, and to reveal the degradation mechanism of pollutants. In this study, we employed sodium ferrate (Na2FeO4) to produce ·OH for the degradation of TPHs in aged oil‐polluted soil located in the western part of the Loess Plateau in China. The results showed that the removal rates of TPH in the soil samples by hydrogen peroxide (H2O2), sodium persulfate (Na2SO4) and Na2FeO4 could reach 45.5%, 62.4%, and 65.6% respectively. The ·OH produced during the process played a major role in TPH oxidation with a contribution of more than 80%; H2O2 was intermediate substance that generated ·OH, biochar could induce the production of ·OH, the addition of biochar could activate H2O2 to promote the generation of ·OH and the removal rate is significantly increased by 19.2%. In situ remediation of polluted soil on the Loess Plateau using Na2FeO4, with a TPH degradation rate of 87.5%. The results of this study will provide a new method for the efficient degradation of TPH in loessial soil. [ABSTRACT FROM AUTHOR]

With the widespread use of membrane in advanced treatment of leachate, China produces a large amount of leachate membrane retentate (LMR) (≈23.4 million tons) annually, which is usually treated by incineration or recirculation in engineering, but these technologies have many drawbacks. LMR is suitable for electrochemical treatment due to its high electrical conductivity. This study compared the performances of electrochemical oxidation (EO) and electro-coagulation (EC) technology on LMR treatment under different experimental conditions, including anode material, current density, initial pH and reaction time. We found that EO optimal conditions achieved 70.1%, 83.1%, 78.7%, 98.7%, and 69.7% removal of total organic carbon (TOC), UV absorption (at 254 nm), chromaticity, ammonia nitrogen (NH 3 –N), and total nitrogen (TN), respectively. Compared with EO, EC exhibited a similar removal ability for orgainics and better removals of chroma, but much less performance for removing nitrogen pollutants in the same reaction time, that is, removals of NH 3 –N and TN were only 31.5% and 36.2%, respectively. Meanwhile, EC showed much higher instantaneous current efficiency of COD than EO under its optimal reaction time (120 min). In addition, the UV–Vis spectra and 3D fluorescence spectra indicated that EO exhibited relatively outstanding performance in decomposing dissolved organic matter (DOM) with rather complicated structures than EC. Also, the flow field-flow fractionation technique demonstrated that EO preferentially destroy humic-like, large molecular weight DOM, and converting them to smaller molecules, which resulted in more volatile organic compounds in EO samples than EC samples. While EC had little selectivity in the removal of organics, except humic-like DOM with relative small molecular. These findings can provide a theoretical basis for the electrochemical treatment of LMR. [Display omitted] • Comparison of performance on EO and EC technology in treating LMR. • 70.12% of TOC, 98.75% of NH 3 –N, and 73% of TN were eliminated by EO. • About 66% TOC, 31% NH 3 –N, and 36% of TN were eliminated by EC. • EO preferentially selected in decomposing CDOM and PDOM with large molecular weights. • EC had little selectivity in the removal of DOM. [ABSTRACT FROM AUTHOR]

Catalytic oxidation is widely used in the treatment of refractory wastewater. However, catalytic oxidation has some problems such as high cost and limited production of radicals. To improve these, in this study, a new process of O 3 /H 2 O 2 /Fe-shavings which coupled catalytic ozonation and Fenton-like oxidation with Fe-shaving wastes reused, was used in the treatment of coking wastewater secondary biochemical effluent (CWSBE). The effects of the environmental conditions on the degradation of CWSBE were studied and the response surface method was used to optimise the parameters. The performances in organic pollutant removal from CWSBE were systematically analysed by a couple of methods such as gas chromatography mass spectrometry and three-dimensional fluorescence. The results showed that macromolecular organics were degraded into small molecules pollutants after treatment by the O 3 /H 2 O 2 /Fe-shavings process. At an ozone concentration of 27.5 mg/L, with the hydrogen peroxide concentration being 10.7 mmol/L, the reaction time 60 min, the initial pH value 3.6, and the pump speed 150 rpm, the COD removal degradation efficiency was 77.5%, and the effluent COD met relevant wastewater discharge standards in China (GB 16171-2012). The mechanism research showed that·OH plays an important role in the degradation of organic pollutants. [Display omitted] • The COD removal efficiency when using the O 3 /H 2 O 2 /Fe-shavings process was 77.5%. • Response surface method was suitable for parameter prediction (R2 Adj >0.97). • The molecular weights of the treated pollutants were majorly <1 kDa (86%). • Fe-shavings improve the concentration of·OH in the O 3 /H 2 O 2 /Fe-shavings process. [ABSTRACT FROM AUTHOR]

The antibiotic fermentation residues derived from the production of a cephalosporin precursor, deacetyloxy cephalosporin C (DOCPC), classified as "Hazardous Waste" in China, was treated by ionizing irradiation from lab-scale experiment to full-scale application. From bench-scale experiments, it was observed that gamma irradiation exhibited a little higher effect to decompose DOCPC than electron beam (EB) irradiation. The removal efficiency of DOCPC reached 97.5% by γ-ray irradiation and 92.9% by electron beam (EB) irradiation at the same absorbed dose of 50 kGy. The rate constant of DOCPC degradation was 1.4 fold (in the fermentation residues) and 1.1 fold (in the supernatant) higher by γ-ray irradiation than that by EB treatment. Oxidation by ·OH was mainly responsible for DOCPC decomposition. The beta-lactam resistance gene cph A was found in the raw DOCPC fermentation residues, with the absolute and relative abundance of 5.1 ⅹ 103 copies/mL and 0.15%, respectively. After 50 kGy of ionizing irradiation, the relative abundance of cph A was abated by 57%. The full-scale EB accelerator was constructed to treat the fermentation residues continuously with the capacity of 100–120 m3/d. During 2 months of operation, the removal efficiency of DOCPC was in the range of 61.5 ± 10.3% with EB intensity of 49 mA, roller frequency of 10 Hz and energy of 1.5 MeV, and it increased to 75–84% after the second irradiation. Ionizing radiation is a promising alternative to treat the antibiotic fermentation residues and the development of electron accelerator and irradiation vessel specific for the fermentation residues treatment is critical for improving the efficiency of industrial application. [Display omitted] • The fermentation residue of cephalosporin (CPC) was treated by ionizing radiation. • CPC degradation in fermentation residue by γ-ray and electron beam was compared. • CPC removal efficiency was 97.5% and 92.9% by γ-ray and EB radiation, respectively. • The abundance of cph A beta-lactam resistance gene decreased by 57% at 50 kGy. • Electron beam technology is promising to treat antibiotic fermentation residue. [ABSTRACT FROM AUTHOR]

• Real OCPs contaminated soil cleanup can be achieved by surfactant-enhanced electrokinetic remediation. • TritonX-100 is a reliable co-solvent for mobilizing hardly soluble OCPs and sustaining Fenton reaction in soil. • TritonX-100-advanced oxidation under electrokinetic is reliable for in situ remediation of real contaminated soil. • The use of external nZVI as oxidant activator is not necessary during the treatment of an iron rich soil. Remediation of organochlorine pesticides (OCPs)-contaminated soils is urgently required especially in China. Surfactants have emerged as reliable and efficient co-solvent for the treatment of hardly soluble organic pollutants in contaminated soil. Here, we report the use of TritonX-100 (TX-100) in advanced oxidation under electrokinetic technology (EK) for OCPs removal from a historically contaminated soil from a former pharmaceutical industrial wasteland. Result shows that TX-100 (10%) played a key role in soil remediation. In effect, after a treatment period of 15 days, pollutants washed ranged from 50.68% (4,4'-DDT) to 76.07% (HCB), when TX-100 was used as the electrolyte (EK-TX-100). A simple advanced oxidation of the soil using sodium persulfate (PS) under EK approach (EK-PS) was limited to achieve good removal efficiency of the pollutants; as the result of OCPs' hardly dissolvable nature. The achieved removal efficiency were comprised between 22.62% (2,4-DDT) and 55.78% (1,2,4,5-TCB). With the application of TX-100 as co-solvent (EK-TX-100/PS), the pollutants removal efficiency significantly improved (p < 0.05). The treatment efficiency was shifted and up to 88.05% (1,2,4-TCB) was achieved, while the lowest removal efficiency was 56.36% (4,4'-DDE). We come to the conclusion that the use of TX-100-enhanced advanced oxidation (EK-TX-100/PS) as a reliable treatment for remediating organochlorine contaminated soil. [ABSTRACT FROM AUTHOR]