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Peracetic acid (PAA) is an emerging oxidant and disinfectant for wastewater (WW) treatment due to limited harmful disinfection byproduct (DBP) formation. Nitrite (NO

Microalgae-based antibiotic removal treatment has attracted attention because of its low carbon and sustainable advantages. The microalgal co-metabolism system with a suitable carbon source leads to enhanced performance of pollutant removal. However, currently, limited knowledge is available for the removal of fluoroquinolone using a microalgae-mediated co-metabolism system. In this study, we first investigated that the biotic processes by alga Haematococcus lacustris in the co-metabolism system by adding glycerol would be the main contributors responsible for the removal of 10 mg/L ofloxacin (OFL) with the efficiency of 79.73% and the removal of 10 mg/ L enrofloxacin (ENR) with the efficiency of 54.10%, respectively. Furthermore, we found that pyruvate from glycerol was converted into substrates and precursors, thereby resulting in the significant accumulations of microalgal astaxanthin and lipid. The astaxanthin content of H. lacustris was achieved at 4.81% and 4.69% treated with OFL and ENR in the presence of glycerol, with 16.04% and 14.55% of lipid content, respectively. The proposed metabolites and pathways were identified to plausibly explain the biodegradation of fluoroquinolone by H. lacustris. The molecular analyses demonstrated that cytochrome P450 (CYP450) enzymes are responsible for the biodegradation of fluoroquinolone, and it was further verified that fluoroquinolones might insert into CYP450 to finally form an efficient and tight binding conformation by molecular dynamic simulation. These findings provide a microalgae-based route for feasible and sustainable biodegradation of antibiotics using a co-metabolism strategy comprising glycerol as a carbon source, with the synergistic accumulation of valuable products., peer-reviewed

Nanomaterials are threatening the environment and human health, but there has been little discussion about the stability and mobility of nanoparticles (NPs) in saturated porous media at environmentally relevant concentrations of surfactants, which is a knowledge gap in exploring the fate of engineered NPs in groundwater. Therefore, the influences of the anionic surfactant (sodium dodecylbenzene sulfonate, SDBS), the cationic surfactant (cetyltrimethylammonium bromide, CTAB), and the nonionic surfactant (Tween-80) with environmentally relevant concentrations of 0, 5, 10, and 20 mg/L on nano-TiO2 (nTiO2, negatively charged) and nano-CeO2 (nCeO2, positively charged) transport through saturated porous media were examined by column experiments. On the whole, with increasing SDBS concentration from 0 to 20 mg/L, the concentration peak of nTiO2 and nCeO2 in effluents increased by approximately 0.2 and 0.3 (dimensionless concentration, C/C0), respectively, because of enhanced stability and reduced aggregate size resulting from enhanced electrostatic and steric repulsions. By contrast, the transportability of NPs significantly decreased with increasing CTAB concentration due to the attachment of positive charges, which was opposite to the charge on the medium surface and facilitated the NP deposition. On the other hand, the addition of Tween-80 had no significant influence on the stability and mobility of nTiO2 and nCeO2. The results were also demonstrated by the colloid filtration theory (CFT) modeling and the Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction calculations; it might promote the assessment and remediation of NP pollution in subsurface environments.

Wastewater recycling helps address the challenge of microalgae biomass commercialization by allowing for efficient resource recovery. In this study, three conventional harvesting methods, including centrifugation, microfiltration, and flocculation sedimentation, were investigated to explore the effects of harvesting methods on the characteristics of recycled wastewater and the growth of microalgae to select a suitable harvesting method for the microalgal wastewater recycling system. During the wastewater recycling process, the least amount of accumulated substances was exhibited in the wastewater recycled by microfiltration, followed by centrifugation, and the most by flocculation sedimentation. After 4 batches of cultivation, microalgal biomass harvested from centrifugation wastewater and microfiltration wastewater was 21.26 % and 13.54 % higher than that from flocculation wastewater, respectively. Lipids, carbohydrates and pigments were all increased by varying degrees. Additionally, flocculation sedimentation was not suitable for the microalgal wastewater recycling process since the low residual nutrients, high salinity, and excessive algal organic matter severely inhibited the growth of microalgae. Under the regulation of phytohormones, microalgae increased their energy reserves, enhanced photosynthesis, and improved their defense capability to resist the increasing abiotic stress. This study provides scientific support for the selection of suitable harvesting technology during the microalgal wastewater recycling process.

Thiosulfate (S

Acrylonitrile wastewater is a kind of highly toxic industrial wastewater, but it contains a lot of valuable chemical materials. In this study, by using the most promising hydrothermal technology, we investigated the best reaction conditions and possible reaction pathways for the conversion of the three nitriles (acrylonitrile, acetonitrile, and succinonitrile) to organic acids under alkaline hydrothermal conditions. Then, the reaction conditions for the conversion of actual acrylonitrile wastewater to organic acids were further optimized. The actual wastewater of acrylonitrile was converted into 1.33 × 104 mg/L acrylic acid, 1.98 × 104 mg/L formic acid and 9.40 × 103 mg/L acetic acid at optimal reaction conditions (reaction temperature 300 °C, reaction time 90 s, and initial NaOH concentration 1.0 mol/L). It is the theoretical basis of the application of the hydrothermal alkali-catalyzed method in the acrylonitrile wastewater resource engineering.

Partial hydrogenolysis of erythritol, which can be produced in large scale by fermentation, to 1,4-butanediol (1,4-BuD) was investigated with Ir-ReOx/SiO2 and Ir-ReOx/rutile-TiO2 catalysts (4 wt% Ir). In addition to the higher conversion rate over Ir-ReOx/TiO2 than over Ir-ReOx/SiO2 which has been also reported in glycerol hydrogenolysis, Ir-ReOx/TiO2 catalyst showed higher selectivity to 1,4-BuD than Ir-ReOx/SiO2 especially at low conversion levels, leading to high productivity of 1,4-BuD: 20 mmol1,4-BuD gIr-1 h-1 at 373 K (36% conversion, 33% selectivity). The productivity based on noble metal amount is higher than those reported in the literature, although the maximum yield of 1,4-BuD (23%) is not higher than the highest ones in the literature. The reactions of various triols, diols and mono-ols were tested and the selectivity and the reaction rates were compared between catalysts and between substrates. The Ir-ReOx/TiO2 catalyst showed about two-fold higher activity than Ir-ReOx/SiO2 in hydrogenolysis of C-OH bond at 2- or 3-positions in 1,2- and 1,3-diols, respectively, while the hydrogenolysis of C-OH bond at the 1-position is less promoted by TiO2 support. Lowering the loading amount of Ir on TiO2 (from 4 wt% to 2 or 1 wt%) decreased the Ir-based activity and 1,4-BuD selectivity. Similarly, increasing the loading amount on SiO2 from 4 wt% to 20 wt% increased the Ir-based activity and 1,4-BuD selectivity, although they were still lower than those of TiO2-supported catalyst with 4 wt% Ir. The high concentration of loaded metals on support is important.

Biochar and hydrochar, as valuable and eco-friendly soil remediation materials from greenwaste, have potential to enhance methane oxidation in paddy soil. But the mechanism of biomass carbon on the improvement of methane-oxidizing bacteria communities in paddy soil has not been adequately elucidated. In the present study, the effect of different-temperature rice straw-based biomass carbon (RB400, RB600, RH250 and RH300) on methane oxidation were investigated by analyzing the soil dissolved organic matter (DOM), physicochemical properties and changes in microbial community structure. The results of the 17-day incubation experiment showed that the methane oxidation rate increased under all types of biomass carbon in the first 6 days. The enhancement of methane oxidation rate was more pronounced for biochar compared to hydrochar, with RB600 being the most effective treatment. The result of excitation-emission matrix (EEM) fluorescence spectroscopy showed that less DOM were released from the soil in the biochar treatments compared to the hydrochar treatments and protein-like were detected only in the hydrochar group. Microbial analysis further showed that hydrochar inhibited the growth of Bacillus, Methylobacter, and Methylocystis, while RB600 significantly increased the relative abundance of methanotrophs (responsible for methane oxidation), such as Methylocystis and Methylobacter, which was consistent with their different effects on the methane oxidation rate. Moreover, from the analysis of principal component analysis (PCA) and canonical correspondence analysis (CCA), Methylobacter and Methylocystis were negatively respond to H/C of biomass carbon. The present study provides a deeper understanding of the effect of biomass carbon obtained by different processes on methane oxidation when applied to soil from the perspective of organic matter and microbial communities.

Frequent human activities in estuary areas lead to the release of a large number of antibiotics, which poses a great threat to human health. However, there are very limited studies about the influence of the special natural phenomena on the occurrence and migration of antibiotics in the environment. In this study, we simulated the migration and transformation of six typical antibiotics, including oxytetracycline (OTC), tetracycline (TC), norfloxacin (NOR), ofloxacin (OFX), erythromycin (ETM) and amoxicillin (AMOX), in the environmental media from 2011 to 2019 in the Yangtze River Estuary, by using the level III multi-media fugacity model combined with the factor of tidal. The simulation results show that the most antibiotics mainly existed in soil and sediment while erythromycin were found mainly in water. The concentrations of antibiotics in air, freshwater, seawater, groundwater, sediment and soil were 10-23-10-25, 0.1-12 ng/L, 0.02-7 ng/L, 0.02-16 ng/L, 0.1-13 ng/g and 0.1-15 ng/g respectively. Sensitivity analysis showed that the degradation rate (Km) and the soil-to-water runoff coefficient (Kl) were important model parameters, indicating that hydrodynamic conditions have a significant impact on the migration of antibiotics in various environmental phases in estuarine areas. Tide can enhance the exchange between water bodies and cause the transformation of the antibiotics from freshwater to seawater and groundwater, which improves the accuracy of the model, especially the seawater and soil phase of it. Risk assessments show that amoxicillin, erythromycin, ofloxacin and norfloxacin pose a threat to the estuarine environment, but the current source of drinking water does not affect human health. Our findings suggest that, when one would like to exam the occurrence and migration of antibiotics in environment, more consideration should be given to the natural phenomena, in addition to human activities and the nature of antibiotics.

Graphene oxide quantum dots (GOQDs) can convert the ultraviolet (200- 380 nm) into available wavelength (400- 700 nm) for microalgae cultivation. However, it has not been applied in large-scale microalgae culture due to its high cost and difficulties in recovery. This study proposed a new strategy for the sustainable use of GOQDs, namely, GOQDs solution was added to the outer sandwich of the reactor. Herein, the effects of direct and indirect exposure of different GOQDs concentrations (0, 100, and 1000 mg/L) on the microalgae culture were compared. When microalgae were directly exposed to the GOQDs, 100 mg/L of GOQDs increased the biomass production of microalgae by 24.0 %, while 1000 mg/L of GOQDs decreased biomass production by 31 %. High concentration of GOQDs (direct exposure) could cause extra oxidative stress in the microalgae cells and result in a significant reduction of pigment content. When microalgae were indirectly exposed to the GOQDs, the increased concentration of GOQDs enhanced the growth of microalgae. Compared to the blank group, 1000 mg/L of GOQDs increased the microalgae biomass production and bioenergy by 14.1 % and 40.17 %, respectively. The indirect exposure of GOQDs can effectively avoid photo-oxidation and organelle damage to the microalgae cells. Overall, the indirect exposure of GOQDs is a sustainable way for effectively promoting microalgae growth and reducing the application cost.

Microplastics (MPs) are susceptible to aging in the environment, and aged MPs are highly migratory in soil due to their smaller particle size and more negative surface charge, but the effects of soil environmental factors on the fate and transport of aged MPs are still unclear. In this study, the transport behavior of pristine/aged MPs in unsaturated sandy porous media was examined under different ionic strength (IS), cationic type (Na

Due to the extremely high stability of perfluorooctane sulfonate (PFOS), effective defluorination is difficult. Previous studies indicated that PFOS can be decomposed under the catalysis of vitamin B12 (VB12) with strong artificial reductants such as Ti(III)-citrate and nZn0. In this study, we explored if naturally occurring reductant like sulfide (S2−) could initiate the reaction. In S2−/VB12 system, branched PFOS (br-PFOS) can undergo effective decomposition and defluorination at the temperature of 70 °C and pH greater than 12. The degradation of br-PFOS fits pseudo-first-order kinetic with a rate constant of 0.0984 ± 0.0034 d-1 in the presence of 30 mM Na2S and 300 μM VB12, while linear PFOS (L-PFOS) remained stable during 30 d reaction process. UV–Vis spectral characterization indicates that S2− reduces VB12(CoIII) to CoII, which is able to initiate the reductive defluorination. Based on the product analysis, HF/2F elimination followed by C–C scission is the dominant degradation pathway of br-PFOS instead of stepwise H/F exchange. The primary products include F− and polyfluorinated sulfonates and carboxylates. The degradation of br-PFOS is strongly dependent on temperature due to a relatively high apparent activation energy of 62.86 kJ/mol. Strong alkaline condition can greatly enhance the decomposition efficiency since S2− is the primary reactive form. This study provides new insights into the VB12-catalyzed defluorination of PFOS and a feasible approach for future natural or engineered remediations of br-PFOS.

HighlightsBatch experiment indicated that sorption of Cd on biochar was highly pH-dependant.The main mechanism of Cd-biochar sorption were surface precipitation and ion exchange.Biochar affected the transportation of the attached Cd.At the same ionic strength, the transportation is faster in the presence of Ca2+ than Na+.Abstract. Cadmium (Cd) is toxic to plants and animals, leaching of Cd through soil profiles can affect its accumulation and pollute the ground-water. In this study, we performed batch and column experiments to study the effect of biochar on the retention and transport of Cd in saturated porous media under different solution chemistry. Specific factors were considered including pH, ionic strength, and biochar dosages. The results of batch experiment indicated that sorption of Cd on biochar was highly pH-dependant, but ionic strength had negligible effect on the adsorption of Cd to biochar. The mechanism of the adsorption process of biochar for Cd mainly involves surface precipitation and ion exchange. In the column experiment, the increase in pH and biochar dosages made the Cd more stable, whereas the increase in ionic strength improved the migration of Cd. The increased retention time of Cd was related to the greater retarded coefficient value (R) based on two-site kinetic retention model. The decrease of partitioning coefficient (ß) and fraction of instantaneous sorption sites (f) were in favor of the continuous and dynamic adsorption under column conditions. This study will provide a theoretical and scientific basis for the rational assessment of cadmium-related risks in biochar-modified environments. Keywords: Adsorption, Biochar, Cadmium, Porous media, Transport.

While aqueous free Cu(II) ion is known to be ineffective to activate peroxydisulfate (PDS), here we report for the first time that Cu(II) complexes are potentially effective activators for PDS when the coordination involves suitable ligands. Using cefalexin (CFX) as a representative, studies show that the complex of Cu(II) with CFX can efficiently activate PDS to induce rapid degradation of CFX. Transformation products of CFX by PDS/Cu(II) differ substantially from those generated from the typical radical oxidation process, for example, PDS/Ag(I), but quite resemble the products from oxidation of CFX by Cu(III). Complexation with CFX increases the electron density of Cu(II), favoring electron transfer from Cu(II) to PDS to generate radicals and Cu(III). The produced Cu(III), rather than radicals, plays the primary role in the overall CFX degradation and regenerates Cu(II) in a catalytic cycle. This novel activation process can occur for a wide range of contaminants (cephalosporin, penicillin, and tetracycline antibiotics) and ligands when coordinated with Cu(II), and N-containing functional groups (e.g. amines) were found to form effective Cu(II) complexes for PDS activation. The new findings of this study further broaden the knowledge on PDS activation by aqueous Cu(II), and verify the contribution of Cu(III) to contaminant elimination.

In this study, the removal of Cr (VI) was examined in the presence of bio-produced Fe (II) from hematite, sulfate and dissolved organic matter by Geobacter sulfurreducens. The adaptation results of G. sulfurreducens showed that cells growth was stimulated up to 576 μM of Cr (VI) concentration. The first-order rate and electron transfer rate in each step during Cr (VI) reduction by G. sulfurreducens in the presence of hematite was clearly modeled and calculated. For Cr (VI) reduction rate, both separately dissolved and adsorbed bio-produced Fe (II) were faster than G. sulfurreducens although bio-produced Fe (II) contributed only 20% to total Cr (VI) removal in a combined system containing Cr (VI), hematite and G. sulfurreducens. The electron transfer rate from G. sulfurreducens to hematite (R2) to produce Fe (II) was a limited step and electron transfer rate from acetate to Cr (VI) (1.8 μeq L−1 h−1) by G. sulfurreducens was much higher than that to hematite (0.272 μeq L−1 h−1, producing Fe (II)). Cr (VI) reduction was enhanced in the presence of SO42− due to sulfate boost cells growth. AQDS enhanced Cr (VI) reduction by serving as an electron shuttle thus accelerating the electron transfer rate.

Cu(II) enhanced the oxygen activation by Fe(II) to increase the yield of oxidants. However the factors controlling the catalytic performance and indeed the underlying influencing mechanisms remained unclear. Here, we presented the detailed study of Cu(II)-Fe(II) reactions for a range of pH and Cu(II)/Fe(II) ratios. From the results obtained, we provided insight into the factors controlling the redox reactions of Fe-Cu and the catalytic behaviours of active species. A reaction scheme for the Fe(II)/Cu(II) system was developed in which the in-situ formed Cu(I) mainly contributed to producing H2O2 and Fe(II) dominantly decomposed H2O2 to hydroxyl radical (HO ) [see companion article] (Yufan Chen). Circumneutral conditions facilitated the catalytic processes; under acidic conditions, the reverse reaction between Fe(III) and Cu(I) was strongly favoured; alkaline conditions improved the reducing capacity, which subsequently enhanced the generation of Cu(0) instead of Cu(I). There was a saturated Cu(II)/Fe(II) ratio above which further addition of Cu(II) could not be reduced, and then excessive Cu(I) and Cu(II) consumed HO and O2 –, respectively. Therefore, the highest removal efficiency of organic pollutants was achieved when the stoichiometric Cu(II)/Fe(II) ratio was 60% at circumneutral pH. The new findings have implications for the treatment of mixed wastewater where copper and organic pollutants coexist.

In this study, nanosized ordered magnetic mesoporous Fe-Ce bimetal oxides (Nanosized-MMIC) with highly well-ordered inner-connected mesostructure were successfully synthesized through the KIT-6 template method. This Nanosized-MMIC displayed excellent adsorption capacities for As(V), Cr(VI) and AO7, and the corresponding calculated maximum adsorption capacities of material were 111.17, 125.28 and 156.52 mg/g, respectively. As(V) and Cr(VI) removal by Nanosized-MMIC were slightly dependent on the ionic strength but highly solution pH-dependent, the coexistent silicate and phosphate ions competed remarkably with both As(V) and Cr(VI) for the adsorption active site. Mechanisms indicated As(V) and Cr(VI) formed inner-sphere complexes on Nanosized-MMIC interface via the electrostatic interaction and surface complexation, while the total organic carbon (TOC) change demonstrated that AO7 could be removed completely and no organic intermediates formed through the adsorption process. In addition, Nanosized-MMIC also possessed superior adsorption performance in As(V)/Cr(VI)-AO7 binary systems, and the reusable and regeneration properties indicated that the obtained nanomaterials could maintain at a comparatively high level after several recycling. Finally, fixed-bed experiments suggested the Nanosized-MMIC was expected to have a promising excellent nano-adsorbent with high application potential for co-existed toxic heavy metals and organic dyes removal in practical wastewater treatment.

Polylactic acid (PLA) is biodegraded rapidly under composting or thermophilic temperature but slowly under natural conditions with substantial microplastics generated. In this study, we examined the feasibility of PLA biodegradation and developed a novel approach for PLA waste management using yellow mealworms (Tenebrio molitor larvae) to achieve biodegradation and resource recovery simultaneously. Results confirmed PLA biodegradation in mealworms as sole PLA and PLA-bran mixtures (10%, 20%, 30% and 50% PLA, wt/wt). Feeding PLA-bran mixtures supported the larval development with higher survival rates and lower cannibal rates than feeding PLA only at ambient temperature. The PLA conversion efficiency was 90.9% with 100% PLA diet and was around 81.5–86.9% with PLA-bran mixtures. A peak insect biomass yield was achieved at a PLA ratio of 20%. PLA biodegradation was verified via detection of chemical and thermal modifications. Gut microbial community analysis indicated that intestinal communities shifted with PLA biodegradation, resulting in clusters with OTUs unique to the PLA diet. Based on these findings, we propose a circular approach for PLA waste management via resource recovery of used PLA as the feedstock for insect biomass production, management of mealworm excrement waste as fertilizer, and utilization of agricultural products for PLA production.

The application of phenylurea herbicides (PUHs) may lead to the extensive distribution in soils, while the role of straw biochar as a soil amendment on the transport and sorption of PUHs are still unclear. Thus, the transport and sorption behavior of three typical PUHs with rice straw biochar (RSB) was studied in both adsorption simulation experiments of aqueous solution and packed column experiments. The sorption mechanism of RSB to herbicides was investigated through batch sorption studies with three influencing factors including dosage of RSB, pH, and ionic strength (IS) with orthogonal test. The sorption coefficients were improved significantly by increasing the dosage of RSB, while there was no obvious influence by enhancing the pH and IS value. The optimal sorption conditions (pH value at 3, IS at 0.1 M, and RSB dosage at 60 mg) of three herbicides were set and the maximum removal rates of Monuron, Diuron, and Linuron were 41.9%, 25%, and 56.8%, respectively. The co-transport process of RSB and PUHs were investigated under different RSB dosage, pH value, and IS value. The retention effect increased greatly with enhancing the RSB dosage and pH value. However, IS did not have a significant influence on the retention of RSB, and therefore it had little effect on the adsorption capacity, which was consistent with the results of sorption experiments. The breakthrough curves (BTCs) for co-transport were well simulated by the two-site non-equilibrium convection–dispersion equation (CDE). Most of the regression coefficients (R2) were above 0.99, which uncovered the co-transport in packed column were affected by physical absorption and chemical forces. According to the fitting parameters analysis, the RSB particles and PUHs were subjected to a greater resistance and a stronger stability by reducing pH value in porous media. The presence of RSB increased the amount of dynamic sorption sites in the entire co-transport system, which led to a significant promotion of the PUHs' sorption and interception.

A series of ordered mesoporous Fe Mn bimetal oxides (OMFMs) were fabricated by using a novel inverse micelle method, and the texture, nanostructure and interface chemistry properties of OMFMs were closely correlated to the calcination temperature. Due to the amorphous regular inner-connected nanostructure and bimetallic synergistic effect, the obtained OMFMs exhibited superior arsenic sequestration performance than pure mesoporous Fe oxides (PMF) and Mn oxides (PMM). The optimum ratio of Fe/Mn and calcination temperature for arsenic removal was 3/1 and 350 °C (OMFM-3), and the maximum As(III) and As(V) adsorption capacities of OMFM-3 were 174.59 and 134.58 mg/g, respectively. Solution pH value negligibly affected the uptake of arsenic (ranged from 3.0 to 7.0), while SiO32−/PO43− ions and humic acid (HA) displayed significant inhibitory effect on arsenic removal by OMFM-3. According to the mechanism of arsenic removal, which simultaneously analyzed the arsenic redox transformation in aqueous phase and on solid phase interface, it was concluded that manganese oxides in OMFM-3 mainly played the role as a remarkable As(III) oxidant in water, whereas iron oxides dominantly acted as an excellent arsenic species adsorbent. Finally, the prominent arsenic sequestration behavior and performance in surface water suggested that OMFM-3 could be a promising and hopeful candidate for arsenic-contaminated (especially As(III)) surface water and groundwater remediation and treatment.

There has been a developing technology in algae with pharmaceuticals wastewater. However, the effect and the underlying mechanism of pharmaceuticals on algae are not well understood. To investigate the effect and mechanism of pharmaceuticalson microalgae, four pharmaceuticals of clofibric acid (CLF), ciprofloxacin (CIP), diclofenac (DCF) and carbamazepine (CBZ) on C. pyrenoidosa culture were analyzed. At low concentrations (a accumulation, lipid accumulation) and activities of antioxidant enzymes were stimulated. The algal metabolite differences of various DCF concentrations were investigated and a total of 91 substances were identified, whose samples were clustered and clearly separated. The key metabolomics pathway analysis found that the DCF promoted the carbohydrate and fatty acid metabolic pathway in C. pyrenoidosa under relatively low concentrations (100 mg/L). The study detected the effects of four pharmaceuticals on C. pyrenoidosa and demonstrated that the usage of metabolomics analysis complemented with DCF could be an effective approach to understand the mechanism of molecular evolution in C. pyrenoidosa for microalgal biomass and bioenergy from wastewater in researches of biological resources.

Toxic heavy metals As(V) and Cr(VI) removal from water environment has becoming more and more urgent due to their adverse health effect. In this study, the flowerlike Ce/Fe bimetallic oxides (CFBO), which combined the superiority of three-dimensionally (3D) hierarchical architectures and bimetallic synergistic effect, were innovatively designed and synthesized via one-step facile template-free hydrothermal method. Compared with pure iron oxides (PIO), the obtained CFBO exhibited excellent performance for As(V) and Cr(VI) removal, and the maximum adsorption capacities toward As(V) and Cr(VI) increased from 49.09 mg/g to 164.94 mg/g and 38.07 mg/g to 127.42 mg/g, respectively. Both As(V) and Cr(VI) removal efficiency decreased with an increasing solution pH due to the pHzpc of CFBO, but exhibited slightly change with coexisting anions except for SiO32− and PO43− ions. Combined results of FT-IR and XPS, it was concluded that the abundant hydroxyl groups existed on the surface of CFBO played a key role in the high uptake of As(V) and Cr(VI), and subsequently formed inner-sphere surface complexes. Attractively, the remarkable removal efficiency of As(V)/Cr(VI) in column experiments revealed that the CFBO had great potential for practical application.

The widespread occurrence of penicillin antibiotics (PENs) in natural environment has raised increasing concerns due to their potential to induce antibiotic-genes. In this study, the degradation of PENs by UV/peroxodisulfate (PDS) process was investigated to determine the reaction kinetics, transformation mechanism and energy efficiency. The second-order rate constants for sulfate radical (SO4− ) and hydroxyl radical (HO ) with PENs, including, pencillin G (PG), amoxicillin (AMX) and carbenicillin (CBN), were determined to be (3.90–9.32) × 109 M−1·s−1 and (6.67–9.86) × 109 M−1·s−1, respectively. A pseudo steady-state kinetic model was employed and successfully predicted the degradation of PENs in ultrapure water. The modeling results revealed that both direct and indirect photolysis contributed to PENs degradation, and the contribution of indirect photolysis increased with the increase of PDS dosage. SO4− was the major contributor to PENs indirect photolysis. The effect of pH and water matrices, including HCO3−, Cl− and natural organic matter were evaluated and modeled. Combined with the modeling results, the derived radicals and excited species were likely generated and involved in the overall degradation of PENs. Based on the developed model, we gave a roughly calculation of electrical energy per order (EE/O) to evaluate the energy efficiency of PDS treatment processes. Finally, the transformation product analysis indicated that the thioether sulfur on the five-membered ring and the side chain, e.g., benzene ring on PG and CBN were the reactive sites for SO4− , while the primary amine was another reactive site for SO4− on AMX.

Sulfidation of nanoscale zerovalent iron (nZVI) has shown some fundamental improvements on reactivity and selectivity toward pollutants in dissolved-oxygen (DO)-stimulated Fenton-like reaction systems (DO/S-nZVI system). However, the pristine microstructure of sulfide-modified nanoscale zerovalent iron (S-nZVI) remains uncovered. In addition, the relationship between pollutant removal and the oxidation of the S-nZVI is largely unknown. The present study confirms that sulfidation not only imparts sulfide and sulfate groups onto the surface of the nanoparticle (both on the oxide shell and on flake-like structures) but also introduces sulfur into the Fe(0) core region. Sulfidation greatly inhibits the four-electron transfer pathway between Fe(0) and oxygen but facilitates the electron transfer from Fe(0) to surface-bound Fe(III) and consecutive single-electron transfer for the generation of H2O2 and hydroxyl radical. In the DO/S-nZVI system, slight sulfidation (S/Fe molar ratio = 0.1) is able to nearly doubl...

Microalgae play an important role in carbon sequestration by converting solar energy into biomass as an energy reserve. The conversion efficiency is often limited by light absorbed in the chloroplast. It is of great potential to enhance the photosynthesis capability by improving susceptibility of the light absorption by microalgae. Carbon-based quantum dots (QDs) are promising candidates for spectrum conversion, exhibiting remarkable biocompatibility, excellent water solubility, and customizable flexibility. Herein, we introduced graphene oxide quantum dots (GOQDs) with a blue light (465 nm) emission after ultraviolet (380 nm) excitation into the microalgae growth media. It is demonstrated that the ultraviolet light was effectively absorbed and utilized by the chlorophyll in the GOQDs-Chlorella pyrenoidosa system, resulting in a significantly increased photosynthetic activity. Moreover, a 20% improvement in carbon dioxide fixation and a 34% increase in bioenergy accumulation was found in the system. We further examined the microalgae metabolic pathways to reveal the biological response mechanism with GOQDs. Results verified that the GOQDs facilitated photosystem II (PSII) energy transfer to improve the photosynthesis of microalgae and upregulated the metabolites of lipid biosynthesis, resulting in a higher biomass and lipid content. This work suggested that using GOQDs as a promising approach for to improve the photosynthetic efficiency of microalgae, as well as a great potential for enhancing carbon capture and bioenergy production, especially in the environments with higher solar ultraviolet irradiation.

The occurrence of tetracycline (TTC) in the environment can exacerbate microbial selection pressure and trigger bacterial resistance, raising potential risks to the ecosystem and public health. Here, we report that copper supported polyurethane foam (Cu-NC) can efficiently activate PMS to degrade TTC. Results demonstrated that the degradation rate of TTC was 91.3% and the pseudo first-order kinetic constant of 0.0762 min−1 was achieved after 40 min reaction at pH 5.0. Activation of PMS by Cu-NC was proposed to proceed via two sequential processes, which was different from the conventional mechanism for sulfate radical generation. Cu0 initially reacts with dissolved oxygen to generate H2O2 and Cu(I)(s) in situ in the solid form. Then Cu(I)(s) solves the relative instability of low-valent transition metal ions in aqueous solution, thus improving the activation efficiency of PMS. A novel mechanism for Cu(I)(s) activation of PMS to generate HO• was proposed and elucidated through outer-sphere interaction (electrostatic bonding) and acid-base theory. Superoxide radical and Cu0 accelerate the Cu(II)/Cu(I) redox, overcoming the rate-limiting step in Fenton-like reaction. Cu-NC showed an excellent cycling stability (80.8% removal efficiency after fifth run) in PMS activation with low Cu ion leaching (＜0.2 mg/L). The Cu-NC/PMS system also exhibited satisfactory removal of TTC in the presence of various water matrices. This study can deepen the understanding of the generation of HO• in the PMS activation process and provide a promising strategy for pollutants degradation in wastewater treatment.

Nanozerovalent iron (nZVI) is widely used for its ability to remove or degrade environmental contaminants. However, the effect of nZVI-pollutant complexes on organisms has not been tested. We demonstrate the ability of a sulfidized derivative of nZVI (FeSSi) to sorb cadmium (Cd) from aqueous media and alleviate Cd toxicity to a freshwater alga for 32 days. FeSSi particles removed over 80% of the aqueous Cd in the first hour and nearly the same concentration of free Cd remained unbound at the end of the experiment. We found that FeSSi particles with Cd sorbed onto them are an order of magnitude more toxic than FeSSi alone. Further, algal-produced organic material facilitates safer remediation of Cd by FeSSi by decreasing the toxicity of FeSSi itself. We developed a dynamic model to predict the maximum Cd concentration FeSSi can remediate without replacing Cd toxicity with its own. FeSSi can remediate four times as much Cd to phytoplankton populations when organic material is present compared to the absence of organic material. We demonstrate the effectiveness of FeSSi as an environmental remediator and the strength of our quantitative model of the mitigation of nanoparticle toxicity by algal-produced organic material.

Inorganic arsenic cycling in the natural environment is significantly controlled by manganese/iron oxides, and studying the redox transformation of arsenic in both aqueous and solid phase is therefore essential to understand its environmental toxicity and predict its environmental behavior. Herein, the synthesized magnetic thin-film MnO 2 nanosheet-coated flowerlike Fe 3 O 4 nanocomposites have been used to simultaneously investigate the potential redox transformation of arsenic in aqueous phase and arsenic speciation on the solid phase interface. The results showed the initial Mn/Fe ratio has serious influenced the morphologies, textural properties and uptake of arsenic in aqueous solution. The maximum adsorption capacities of As(III) and As(V) by MF2 were 76.73 mg/g and 120.50 mg/g, respectively. After 10 h reaction, the total arsenic concentration in both As(III)-MF2 system and As(V)-MF2 system far below than that of 10 μg/L, which was setted the maximum guideline concentration value in drinking water by World Health Organization (WHO). HPLC-ICP-MS revealed that in aqueous solution part of As(III) was oxidized into As(V), while As(V) was not reduced into As(III). X-ray absorption near edge structure (XANES) and XPS analysis from solid phase further confirmed that the MnO 2 nanosheet mainly acted as an oxidant, while flowerlike Fe 3 O 4 only played the role as an arsenic species adsorbent. Extended X-ray absorption fine structure (EXAFS) analysis indicated that both As(III) and As(V) formed inner-sphere bidentate binuclear corner-sharing ( 2 C ) complexes with an As-Fe interatomic distance of 3.32–3.34 A on the interface of As-MF2 solid phase.

The widely used carbamazepine (CBZ) is one of the most persistent pharmaceuticals and suffers insufficient removal efficiency by conventional wastewater treatment. A synthesized Co-based perovskite (LaCoO3) was used to activate peroxymonosulfate (PMS) in order to degrade CBZ. Results showed that LaCoO3 exhibited an excellent performance in PMS activation and CBZ degradation at neutral pH, with low cobalt leaching. The results of FT-IR and XPS verified the high structurally and chemically stability of LaCoO3 in PMS activation. Electron spin resonance (ESR) analysis suggested the generation of radical species, such as sulfate radicals (SO4 -) and hydroxyl radicals ( OH). Radical quenching experiments further revealed the responsibility of SO4 - as the dominant oxidant for CBZ oxidation. Ten products were detected via the oxidation of CBZ, with the olefinic double bond attacked by SO4 - as the initial step. Hydroxylation, hydrolysis, cyclization and dehydration were involved along the transformation of CBZ. The toxicity of CBZ solution was significantly reduced after treating by PMS/LaCoO3.

Yellow mealworms (larvae of Tenebrio molitor, Coleoptera: Tenebrionidae) have been proven to be capable of biodegrading polystyrene (PS) products. Using four geographic sources, we found that dark mealworms (larvae of Tenebrio obscurus) ate PS as well. We subsequently tested T. obscurus from Shandong, China for PS degradation capability. Our results demonstrated the ability for PS degradation within the gut of T. obscurus at greater rates than T. molitor. With expanded PS foam as the sole diet, the specific PS consumption rates for T. obscurus and T. molitor at similar sizes (2.0 cm, 62-64 mg per larva) were 32.44 ± 0.51 and 24.30 ± 1.34 mg 100 larvae-1 d-1, respectively. After 31 days, the molecular weight ( Mn) of residual PS in frass (excrement) of T. obscurus decreased by 26.03%, remarkably higher than that of T. molitor (11.67%). Fourier transform infrared spectroscopy (FTIR) indicated formation of functional groups of intermediates and chemical modification. Thermo gravimetric analysis (TGA) suggested that T. obscurus larvae degraded PS effectively based on the proportion of PS residue. Co-fed corn flour to T. obscurus and wheat bran to T. molitor increased total PS consumption by 11.6% and 15.2%, respectively. Antibiotic gentamicin almost completely inhibited PS depolymerization. High-throughput sequencing revealed significant shifts in the gut microbial community in both Tenebrio species that were associated with the PS diet and PS biodegradation, with changes in three predominant families (Enterobacteriaceae, Spiroplasmataceae, and Enterococcaceae). The results indicate that PS biodegradability may be ubiquitous within the Tenebrio genus which could provide a bioresource for plastic waste biodegradation.

Coking wastewater (CWW) is one of the most challenging industrial wastewaters to treat, due to its complex chemical composition, high organic load, and potential toxicity to human and environmental health. A full-scale coking wastewater treatment plant with a two-stage anoxic-oxic-anoxic-oxic (A1/O1/A2/O2) process was investigated systematically. The experimental results showed that the AOAO process exhibited an excellent removal capacity of COD, ammonia, nitrate, and total nitrogen. The GC × GC-TOF MS analysis investigated that the majority of refractory organic compounds, such as phenols, quinolines, polycyclic aromatic hydrocarbons, hydrocarbons, etc., were either fully decomposed or exhibited significant decreases in concentration during the full-scale AOAO process, which offered insights to the biodegradation dynamics of CWW organic components. Microbial community analysis showed that bacterial communities were remarkably altered in the four bioreactors of the AOAO process: Proteobacteria dominated during the whole AOAO process, while Nitrospirae and Bacteroidetes enriched in the primary and secondary AO process, respectively. Moreover, metagenomic sequencing found that the relative abundances of amino acid metabolism and carbohydrate metabolism in the primary AO process were both higher than that in the secondary AO process. It indicated that as the AOAO process progressed, the changes in operational characteristics could remarkably affect the variations of functional microorganisms responsible for organics and nitrogen removal and metabolic functions of microbial community. Through this study, a comprehensive assessment of the AOAO biological processes of coking wastewater treatment was achieved, which provided valuable insights to the operation and evaluation of relevant real treatment plants.

Microalgae residue was efficiently converted into lactic acid with a high yield (33.9%) under mild reaction conditions (210 °C, 2 h) over a Fe-Sn-Beta catalyst. Under the action of homogeneous H3O+ and distinct Lewis acid sites on the catalyst, the production of lactic acid from microalgae residue underwent three main reaction steps: hydrolysis, isomerization, and retro-aldol condensation. Results demonstrated that the lipid component had a strong inhibitory effect on the production of lactic acid due to the formation of aromatics, esters, and complex nitrogenous heterocyclic compounds, which covered or poisoned the Lewis acid sites of the catalyst. The protein component acted as a chemical buffer that enhanced the production of lactic acid by controlling the release of monosaccharides from the carbohydrate fraction of microalgae and maintaining the catalytic activity of the catalyst. Thus, microalgae residue demonstrated great promise for the production of value-added chemicals.

To solve the problem of organic and inorganic arsenic species contamination in drinking water and/or wastewater, porous biochar-supported MnFe2O4 magnetic nanocomposite (BC-MF) was successfully fabricated and used as an excellent adsorbent for simultaneous removal of p-ASA and As(V) from water environment. This obtained BC-MF displayed remarkable adsorption performance for both p-ASA and As(V) removal at acidic and neutral pH (3−7), and di-anionic and mono-anionic species of p-ASA and As(V) facilitated the adsorption process. Specifically, BC-MF exceeded some reported adsorbents, and the adsorption capacities of p-ASA and As(V) were approximately 105 and 90 mg/g at a 10 μg/L equilibrium concentration. Satisfactory adsorption behavior including adsorption isotherms, competitive ions, humic acid (HA), and regeneration/reusability property in single and binary systems demonstrated the BC-MF can improve the potential application for arsenic-containing wastewater remediation. Proposed adsorption mechanism indicated that electrostatic interaction and surface complexation were involved the p-ASA and As(V) immobilization, whereas hydrogen bonding and π-π interactions may also contribute to the p-ASA removal. Additionally, the prominent sequestration p-ASA and As(V) performance in different water matrix and fixed-bed column studies indicated that BC-MF was a promising nanocomposite for simultaneously removal of organic and inorganic arsenic species in practical wastewater treatment.

While peracetic acid (PAA) are known to be susceptible to decomposition by metals for radical generation, herein we report a novel decomposition process of PAA with TiO2 nanoparticle (nTiO2) for the first time. nTiO2 in anatase (A_nTiO2) could significantly enhance the decomposition of PAA, whereas, nTiO2 in rutile phase had no impact on the stability of PAA. Electron paramagnetic resonance (EPR) technique and a radical quenching study indicated lack of involvement of reactive radicals. In-depth investigation revealed that the {0 0 1} facets of A_nTiO2 with high surface free energy were especially reactive for the catalytic decomposition of PAA. Theoretical calculations proved the adsorption of PAA onto A_nTiO2 {0 0 1} surface was much more favorable than the predominated {1 0 1} facets. The unsaturated five coordinated Ti (Ti5c), typical Lewis acid sites on A_nTiO2 {0 0 1} surface, were further confirmed as the dominant active sites for catalyzing PAA decomposition. This novel decomposition process could enhance the stability and migration of A_nTiO2, increasing the potential environmental risk. Meanwhile, the disinfection of PAA was inhibited by introducing A_nTiO2. The new findings of this study broaden the knowledge on PAA decomposition process, and have an important implication for PAA disinfection and environmental behavior of TiO2 nanoparticle.

Degradation of pollution for specific chemicals represents an optimal approach to high-strength wastewater treatment. One-pot selective conversion of acrylonitrile to acrylic acid in a hydrothermal system with NaOH as a catalyst was carried out. The influence factors were evaluated, including initial acrylonitrile concentration, reaction temperature, reaction time and amount of alkali. Experimental results showed that the highest yield of acrylic acid (55%) was obtained at the initial acrylonitrile concentration of 3 × 103 mg/L, 300°C for 90 s with 1.0 M NaOH. To determine the reaction path, intermediates analysis and calculation of carbon and nitrogen balance were carried out by means of HPLC, GC and TOC/TN methods. Two probable reaction pathways were proposed as follows: (1) Acrylonitrile was hydrolyzed into acrylamide, and acrylic acid was obtained via further hydrolysis. (2) Acrylonitrile was converted into 3-hydroxy-propionitrile via additive reaction, and this product was readily converted to 3-hydroxy-propionic acid through two steps of hydrolysis, followed by dehydration reaction to produce acrylic acid. This study offered not only an efficient method to transfer highly toxic pollutants into valuable chemical, but also a better understanding of hydrothermal alkali catalytic reaction.

The potential performance of thermally activated persulfate (TAP) oxidation on the degradation of Triclosan (TCS), a widely used antibacterial agent, was investigated under different conditions. TCS degradation by TAP oxidation was found to fit well with an Arrhenius behavior from 50 to 80 °C, yielding apparent activation energy 121.12 kJ/mol. TCS removal was found to be pH-dependent. Acidic conditions (pH 3–5) were beneficial to TCS removal. The performance of TAP oxidation was still promising under circumneutral pH value (pH ∼7). The presence of alkaline species (with concentrations ranging from 1 to 50 mM) presented inhibitory effects on TCS degradation. When concentration of fulvic acid (FA) in solution increased to 10 mg/L, the effect on TCS degradation became increasingly negative. Different with alkaline species and FA, chloride ions at relatively low ( 10 mM) and high (20–50 mM) concentrations exhibited dual effects on TCS degradation. Both sulfate radicals and hydroxyl radicals were confirmed in the system by Electron Paramagnetic Resonance spectra, and the quenching study indicated that sulfate radicals were the predominant oxidants responsible for the TCS degradation. The major intermediate derived from TCS degradation was identified to be 2,4-dichlorophenol and the reaction scheme was proposed. Additionally, the ecotoxicity of TCS and its degraded samples was assessed by a 4-day zebrafish embryo-larval bioassay, which indicated the capacity of thermally activated persulfate oxidation to decrease ecotoxicity, thus confirmed the sulfate radicals based oxidation a promising alternative of in situ chemical oxidation from the environmental risk standpoint.

The widely used β-lactam antibiotics such as penicillins and cephalosporins are known to be susceptible to CuII-catalyzed hydrolysis at their four-membered β-lactam ring. However, this study elucidates that CuII can in fact play multiple roles in promoting the hydrolysis and/or oxidation of β-lactam antibiotics under environmental aquatic conditions (pH 5.0–9.0 and 22 °C), depending on β-lactams’ structural characteristics and solution pH. Most significantly, the β-lactam antibiotics that contain a phenylglycine primary amine group on the side chain can undergo direct oxidation by CuII via this functional group. On the other hand, the β-lactam ring of penicillins is susceptible to CuII-catalyzed hydrolysis, followed by oxidation of the hydrolysis product by CuII. In contrast, the β-lactam ring of cephalosporins is susceptible to CuII-catalyzed hydrolysis only. Solution pH influences the CuII-promoted transformation by affecting the β-lactam and CuII complexation through protonation/deprotonation of critic...

Inspired by iron fertilization experiments in HNLC (high-nitrate, low-chlorophyll) sea areas, we proposed the use of iron-rich engineered microalgae for microbial contaminant control in iron-free culture media. Based on the genome sequence and natural transformation system of Synechocystis sp. PCC6803, ftnA (encoding ferritin) was selected as our target gene and was cloned into wild-type Synechocystis sp. PCC6803. Tests at the molecular level confirmed the successful construction of the engineered Synechocystis sp. PCC6803-ftnA. After Fe(3+)-EDTA pulsing, the intracellular iron content of Synechocystis sp. PCC6803-ftnA was significantly enhanced, and the algae was used in the microbial contamination control system. In the coupled Synechocystis sp. PCC6803-ftnA production and municipal wastewater (MW, including Scenedesmus obliquus and Bacillus) treatment, Synechocystis sp. PCC6803-ftnA accounted for all of the microbial activity and significantly increased from 70% of the microbial community to 95%. These results revealed that while the stored iron in the Synechocystis sp. PCC6803-ftnA cells was used for growth and reproduction of this microalga in the MW, the growth of other microbes was inhibited because of the iron limitation, and these results provide a new method for microbial contamination control during a coupling process.

The influence of a biodegradable agent, N,N-bis(carboxymethyl)glutamic acid (GLDA), on chloramphenicol (CAP) degradation in pyrite/H2O2 system was investigated. The results indicated that the presence of GLDA could extend the working pH range and provided favorable performance at alkaline conditions. The addition of 100 μmol/L GLDA increased the CAP removal rate to 83.3% at pH 8 due to the reinforced formation of OH. The beneficial effect was found to be indifferent of possible reduction of redox potential (Fe(III)/Fe(II)), probable decrease of reaction pH and complex of structured iron on pyrite surface. However, it was correlated well with the facilitated autocatalytic oxidation reaction by Fe(III)-GLDA that promoted cycle of iron, which was confirmed by the determination of ESR and sulfate ion leaching. Based on GC–MS results, the presence of GLDA led to further oxidation of product with reinforced oxidation efficiency, and the potential degradation routine remains similar. All these provide some fundamental insights into the characteristics of environment friendly GLDA-enhanced pyrite/H2O2 system for bio-refractory contaminants removal under neutral or alkaline conditions, and enrich the theoretical knowledge of heterogeneous Fenton-like processes.