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This study aimed to develop a multistage treatment system for highly toxic wastewater named reverse osmosis concentrates (ROC) of landfill leachate (LL). Therefore, a combination of the ammonia stripping process (ASP), catalytic ozone oxidation process (COP) and Heterotrophic Nitrification Aerobic Denitrification process (HNADP) was proposed and the quality of effluent was evaluated for the concentration of Chemical Oxygen Demand (COD), ammonia nitrogen (NH4+-N) and total nitrogen (TN). ASP had moderate removal efficiency of NH4+-N, and TN in the effluent. COP was catalyzed by cerium supported activated carbon (Ce-AC) achieved good performance in disposal of COD. The effluent of HNADP had the most significant removal efficiency of COD, NH4+-N, and TN. As a result, the effluent of combined process successfully met the discharge standards for NH4+-N and TN according to Table 2 of GB 16889-2008 in China. To investigate the microbial mechanism of pollutant removal in HNADP, 16S rRNA high-throughput sequencing was performed and the results suggested that the relative abundance and diversity of microorganisms fluctuated with the changes of COD/TN ratio(C/N) in HNADP. Truepera and Halomonas were identified as the key genera involved in the simultaneous degradation of COD and nitrogen-containing pollutants, the functional genes (hao, amoA, nirS and nirK) were predicted in nitrification and denitrification process. Overall, this study demonstrates a feasible multistage system for treatment of ROC and propose that further explorations of combined techniques may lead to even more satisfactory removal efficiencies.

Low-molecular-weight dissolved organic nitrogen (LMW-DON) is an emerging issue in concentrated leachate (CL). Ozonation is crucial to remove LMW-DON, but selectivity mechanisms of different reactive oxygen species were unknown. Here, reactions of O

Forced aeration is one of the promising ways to accelerate landfill reclamation, and understanding the relation between aeration rates and waste properties is the prerequisite to implementing forced aeration under the target of energy saving and carbon reduction. In this work, landfill reclamation processes with forced aeration were simulated using aged refuses (ARs) of 1, 4, 7, 10, and 13 disposal years, and the potential of field application was also investigated based on a field project, to identify the degradation rate of organic components, the O2 consumption efficiency and their correlations to microbes. It was found that the removal rate of organic matters declined from 20.3% (AR1) to 12.6% (AR13), and that biodegradable matter (BDM) decreased from 5.2–2.4% at the set aeration rate of 0.12 L O2/kg DM/day, respectively. A linear relationship between degradation rate constant (K) of BDM and disposal ages (x) was established: K=-0.0002193x + 0.0091 (R2 = 0.854), suggesting that BDM might be a suitable indicator to reflect the stabilization of ARs. The cellulose/ lignin ratio decrease rate for AR1 (18.3%) was much higher than AR13 (3.1%), while the corresponding humic-acid/ fulvic-acid ratio increased from 1.44 to 2.16. The dominant bacteria shift from Corynebacterium (9.2%), Acinetobacter (6.6%), and Fermentimonas (6.5%), genes related to the decompose of biodegradable organics, to Stenotrophomonas (10.2%) and Clostridiales (3.7%), which were associated with the humification. The aeration efficiencies of lab-scale tests were at the range of 5.4–11.8 g BDM/ L O2 for ARs with disposal ages of 1–13 years, and in situ landfill reclamation, ARs with disposal age of 10–18 years were around 1.9–8.8 g BDM/ L O2, as the disposal age decreased. The increased discrepancy was observed in ARs of lab-scale and field scale, indicating that the forced aeration rate should be adjusted based on aged refuses and the unit compartment combined, to reduce the operation cost.

A novel nanocomposite, named as nZVI@LH, was prepared by nanoscale zero-valent iron (nZVI) supported on lignin hydrogel and was used in the remediation of Cr(VI)-contaminated soil collected from an industrial site. Meanwhile, scanning electron microscopy with energy dispersive X-ray (SEM-EDX) and X-ray diffractometry (XRD) results determined that nZVI nanoparticles disperse uniformly on hydrogel. After the 14 days remediation, the immobilization efficiency of Cr(VI) could reach over 87% in the treatment of 3% (w/w%) nZVI@LH and 26% in the treatment of bare-nZVI. Leaching experiment results showed that the treatment group with 3% (w/w%) nZVI@LH was up to the national leaching toxicity identification standard, and there was no threat in simulation of acid rain over the long term. The water-soluble (WS) fraction in 3

Anaerobic digestion (AD) is a promising technology to treat waste-activated sludge, previous study proved that methane production could be enhanced with the addition of choline, this work aimed to solve the problem of rapid biodegradability of choline in the AD process by changing its dosing method. With 0.75 g/L as the optimal choline dosing concentration, experimental results showed that successive choline dosing during the first 3-6 days of AD (experimental groups, EGs) performed better than the single dosing. The accumulative biogas production in EGs was increased by 35.55-36.73%, which could be caused by the simultaneous promotion of hydrolysis-acidification and methanogenesis processes. Especially, the electron exchange capacity of digested sludge in EGs was increased by 16.71-34.58%. In addition, the surface Gibbs free energy (△G

As an important Energy Internet technology, energy router (ER) can implement energy routing and information interconnection for the electrical grid within a certain geography range. However, multi-energy supply allocation between multi-energy routers (MERs) has to be resolved, which can connect isolated area networks and expand the scale of the energy Internet. In this paper, equipment capacity and network routing are planned for multi-area multi-energy system (MAMES), which integrates multiple MERs with a virtual multi-energy router (VMER). Firstly, based on the VMER, the concept of MAMES is proposed. Then, the correlation model of multi-energy networks in VMER is constructed, based on MER energy transmission conversion extension model and hybrid power flow model. And the novel routing algorithm is proposed to determine the energy candidate set of the integrated energy networks. During planning, the random scenario generation based on Latin hypercube sampling (LHS) and scenario reduction based on k-means clustering are applied. Finally, the simulation shows that the planning method based on the routing algorithm can effectively obtain the capacity of energy equipment inside MERs and the routing layout between MERs in the MAMES. Proposed routing algorithm and operation scenarios reduction greatly improve the efficiency of planning. Correlated planning helps improve energy efficiency, environment protection, and economic benefits of MAMES.

Centralized biological treatments, i.e., anaerobic digestion (AD) and in-vessel composting (IVC), were supposed to be the promising processes for the disposal of food waste (FW) after source separation, while the systematic benefits were unclear for FW with high water content, salt and oil and thus influenced the selection by the local decision-makers. In this study, two large-scale working AD and IVC plants were compared for environmental impacts, nutrient recovery and economic benefits. For unit amount of FW, 89.26 kg CO

The sequestration of carbon from the sewage sludge to prepare a useful sludge-based carbon (SBC) could be one of the sustainable alternative methods for the solution of sludge in cities. In this work, a novel method of ‘site-occupied firstly and decomposed subsequently’ was developed to increase the sludge-based carbon (SBC) quality. The urea was designed to generate CO2 and NH3 firstly during the decomposition process around 150–250 °C, and to form HCNO and g-C3N4 at 360 and 550 °C in series. Three times higher BET surface area was observed after 30% urea treated SBC (wurea/wsludge = 3/10, SBC30%u), from 97 ± 4.1 m2/g to 300 ± 7.4 m2/g. The point of zero charge (PZC) of SBC30%u decreased to 3.8 ± 0.23 from 5.4 ± 0.20 (PZC of the untreated SBC) due to the generation of acidic groups. The acidic functional groups generated, such as –C O, –OH, were also confirmed by the FTIR analysis. The SBC obtained was used for the further treatment of leachate effluent, and the corresponding COD removal ratio increased from 21.6% to 50.2% in SBC30%u. It can be concluded that the site-occupied and decomposed process could be a potential process to pyrolysis for the sludge-like complex raw material.

Ammonia leaching has recently been applied to leach metals from cathode scrap of the spent lithium-ion batteries (LIBs), and the performance of the manganese-based catalysts recovered from the reclamation of the residues produced in the leaching process was investigated in this study. The results showed that the origin residue from ammonia leaching was converted into mangano-manganic oxide (Mn3O4) and nickel manganese (NiMn2O4) after calcination. The catalytic activity of the recovered manganese-based catalysts could be efficiently enhanced after ball grinding for 15 min, with the degradation of methylene blue (MB) from 11% to 40%. Characterizations were carried out by X-ray diffraction (XRD), BET, particle size analysis, scanning electron microscope (SEM) as well as Fourier Transform infrared spectroscopy (FT-IR). It was found that the increase of the surface area and the reduction of particle size after grinding would be a benefit to improve the catalytic activity. It was indicated that the catalytic performance of the manganese-based catalysts recovered from ammonia leaching residues by calcination could be improved by mechanical methods.

Concentrated leachate is collected from two-stage anaerobic/aerobic-membrane bioreactor (MBR) and nanofiltration (NF) unit in landfill leachate treatment process and featured with non-biodegradation compounds and high salts content. E+-ozonation process was developed and introduced to deal with concentrated leachate, to make good use of chlorine ions (Cl−) and the associated O2 during ozonation process. 74.5% and 69.7% of COD and TOC were removed in E+-ozonation under the optimum conditions with initial pH of 9 and current density of 30 mA∙cm−2, and the corresponding enhancement factors were 1.36 and 1.13, compared to the sum of the electrolysis and ozonation individual. The co-generation of reactive oxygen species (ROS) and reactive chlorine species (RCS) made a complementary effect on the degradation of refractory substances presented in concentrated leachate. 10.1% of total COD removal was improved by non-radical RCS generated in situ and 6.5% of total COD removal was achieved by ●OH-enhanced and Cl /ClO -emerged. With the help of electrolysis, the OH quencher of Cl− was converted into non-radical RCS (such as Cl−, ClO− and Cl2) at anode, and the un-reacted O2/O3 was reduced into OH at the cathode simultaneously. E+-ozonation offers a synergetic degradation potential for special wastewater with refractory matters and high Cl− content.

Using microalgae to remove pharmaceuticals and personal care products (PPCPs) micropollutants (MPs) have attracted considerable interest. However, high concentrations of persistent PPCPs can reduce the performance of microalgae in remediating PPCPs. Three persistent PPCPs, namely, carbamazepine (CBZ), sulfamethazine (SMT) and tramadol (TRA), were treated with a combination of Chaetoceros muelleri and biochar in a photobioreactor during this study. Two reactors were run. The first reactor comprised Chaetoceros muelleri, as the control, and the second reactor comprised Chaetoceros muelleri and biochar. The second reactor showed a better performance in removing PPCPs. Through the response surface methodology, 68.9% (0.330 mg L&minus, 1) of CBZ, 64.8% (0.311 mg L&minus, 1) of SMT and 69.3% (0.332 mg L&minus, 1) of TRA were removed at the initial concentrations of MPs (0.48 mg L&minus, 1) and contact time of 8.1 days. An artificial neural network was used in optimising elimination efficiency for each MP. The rational mean squared errors and high R2 values showed that the removal of PPCPs was optimised. Moreover, the effects of PPCPs concentration (0&ndash, 100 mg L&minus, 1) on Chaetoceros muelleri were studied. Low PPCP concentrations (&lt, 40 mg L&minus, 1) increased the amounts of chlorophyll and proteins in the microalgae. However, cell viability, chlorophyll and protein contents dramatically decreased with increasing PPCPs concentrations (&gt, 1).

Concentrated leachate (CL), characterized with high content salts and compositional complexity of dissolved organic matter (DOM), is difficult to degrade. Understanding the CL from molecular insight level is the requirement for further disposal based on their components. Here, typical CL samples were collected from the multi-stage membrane separation process in a large-scale leachate plant, including nanofiltration (NF), primary ultrafiltration (PUF), secondary nanofiltration (SNF), and reverse osmosis (RO). More than 95% of DOM was removed from raw CL, of which about 3/4 flowed into PUFCL and 1/5 flowed into SNFCL. DOM with macro-molecular weight (500 Da, 30.46%) and highly unsaturated compounds (double-bond equivalents15) were detected in PUFCL. Nearly half of DOM was CHO-only compounds (42.04%) in SNFCL. PUFCL was abundant in heteroatom species with higher-order oxygen (O ≥ 10), which was coincident with the trend of humic substance distribution (humic substance1/2). Based on these properties results, advanced oxidation processes, such as ozonation, might be the right process for SNFCL rich in heteroatom species with low-order oxygen (O 10). Abundant disulfides (S

Development of anaerobic digestion (AD) technology in China for WWTP sludge treatment is hindered by low biomethane yield and costly biogas upgrading. This study investigated the feasibility of using a byproduct waste, sludge incineration bottom ash, as additive to promote AD performance. The effectiveness of ashes addition was investigated with varied dosages (0.6–1.5 g/g dry matter (DM) of sludge) to enhance thermophilic AD of sludge in batch experiments in terms of methane production and CO2 sequestration. The optimal dosage was 0.9 g/g DM, which increased the methane production by 26.6%, shortened the methanization lag phase by 32.4% and increased the maximum methane production rate by 36.0%. Kinetics modelling results show that ashes additive accelerated hydrolysis, acidogenesis and degradation of volatile fatty acids (VFAs) by up to 139.6%, 87.1% and 100.9%, respectively. High dosage at 1.5 g/g DM output the greatest sludge hydrolysis and VFAs production but inhibited methanogenesis. Moreover, the amount of sequestered CO2 resulting from basic cations (primarily Ca2+) leaching in ashes-amended digesters was linearly correlated (R2 > 0.99) with the dosage of ashes additive. This indicates that ashes addition facilitated in-situ carbonation in AD system and that Ca2+ leaching remains rate-limiting. The results demonstrated that sludge incineration bottom ash could be used as an effective additive material to improve AD of sludge, thus enhancing the technical and economic feasibility of AD technology for sludge treatment.

Fluorine in etching wastewater is an important F resource, and the development of a high value-added fluorine based compounds could benefit for the fluoride resource saving and the reduction of fluoride effluent. In this work, F from etching wastewater was recovered by composites of CaF 2 and CaSO 4 , which was used to prepare as the near infrared photocatalyst of Tm 3+ /Yb 3+ co-doped ((CaF 2 /CaWO 4 )@Bi 2 WO 6 ) (TY-CCB). It was found that CaWO 4 was fabricated by the slow release of Ca 2+ ions from CaSO 4 particles according to XRD and XPS results, and the heterostructure between CaWO 4 and Bi 2 WO 6 were formed in the TY-CCB composite with flat-shape morphology, which could improve the photocatalytic activity. The upconverted UV (364 nm) and blue (484 nm) light were observed upon 980 nm NIR irradiation, combined with the extended absorption band of 519 nm in TY-CCB. For the degradation of methyl orange (MO) and salicylic acid (SA), the corresponding degradation rate of 0.44 and 0.42 mg L −1 ·h −1 were obtained after 3 h under NIR light irradiations, and both of them increased to 2.78 and 1.74 mg L −1 ·h −1 under UV–vis–NIR light irradiations, respectively. Fluorine recovery through the preparation of TY-CCB upconversion photocatalyst was a mutually beneficial approach.

Co-pyrolysis can enhance the sewage sludge sequestrated carbon quantity through the introduction of other carbon containing precursors. In this work, wind turbine blade waste (WTBW) was used to perform a co-pyrolysis system of sludge at 600 °C, in presence of activating agent KOH. The optimum mass proportion of WTBW was 40% for carbon material preparation in terms of surface area, and the apparent activation energy. The apparent activation energy was observed to decrease from 53.5 kJ/mol to 33.1 kJ/mol as the WTBW mass proportion increased from 0 to 40%. The maximum BET surface area was found to be 498.3 m2/g, whereas, 36% more micro-pores were generated in the carbon mateirals. The major functional groups in the co-pyrolysis carbon material were found to be hydroxyl and aldehydes. The co-pyrolysis of WTBW and sewage sludge will be a promising way to improve the carbon sequestration from sewage sludge.

Plastic recycling is critical for dematerializing of plastics. It has a profound implication on decoupling economic growth from environmental pressure and advancing waste plastic governance domestically and internationally while identifying drivers that might improve decoupling. In this study, plastic consumption and recycling patterns are presented, and the factors influencing the acceleration of dematerialization subsequent to the ban were investigated in the G7 countries and China. The results show that plastic consumption increases from 7.60 million metric tons (mt) to 12.60 mt between 2017 and 2019, and subsequently rapidly decreases to 6.84 mt in 2020. The plastic recycling rate drastically decreased by 21.3% in 2017, and decreased slightly from 2017 to 2020, at an annual rate of 2.9% on average. China's ban shocked the decoupling trends, which showed resilience and motivated the development of robust plastic recycling, and the global recycling transformation pattern accelerated the dematerialization of plastics. Decoupling performances of the G7 and China gradually stabilized in 2019, and all the countries were strongly decoupled in 2020, although decoupling index (DI) fluctuates from 2017 to 2020. Among the recycling-trading drivers, the improvement of waste plastic quality in recycling contributes more to decoupling, the recycling rate shows a more negative decoupling effect on China before the ban, and the population effect is weak relative to other influencing factors. The factors revealed the mechanism of decoupling of plastic consumption in the recycling-trading process, and the recyclability improvement in terms of plastic quality is important for dematerialization.

As an important anthropogenic greenhouse gas (GHG) emission source, GHG emission pattern from municipal solid waste (MSW) sector is unclear, which impairs the effective decision making for potential GHG reduction. The variations tendency of GHG inventories were studied from 1949 to 2013 in China on the basis of first order decay (FOD) method, and the total estimated GHG was found to be increased from 0.36 to 72.4 Mt CO2-equiv in this work. Landfill was the main contributor for the GHG emissions, and the occupied percentage increased from 17% in 1979, to the peak value of 82% in 1999, and finally to 69.5% in 2013. The regional GHG division patterns were calculated every 5 years after 2003 due to the remarkable increase of MSW in past decades. East China was found to be the dominant region for GHG emissions, while the corresponding percentage decreased from 38.60% in 2003 to 30.75% in 2013. The percentage increased from 4.69% to 7.31%, as more MSW were landfilling in North West. The methane mitigation technologies, especially the soil cover and landfill gas collection-flaring, are the main contribution for CH4 reduction. The diversion alternatives for landfill are effective in the indirect GHG mitigation, and the reduction of MSW disposal is another critical part through the implementation of “pay-as-your-throw” and environmental protection tax.

Dissolved organic matter (DOM) is a critical component of high-strength organic wastewater, and the study of them from molecular perspective could improve the removal efficiency. Leachate samples were collected from China’s largest two stage anaerobic/aerobic membrane bioreactor and nanofiltration (A/O-MBR-NF) process, with the treatment capacity of 5000 t/d, and characterized by electrospray ionization (ESI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) from molecular perspective. High molecular weight (m/z > 500) compounds with 40–50 carbon atoms and 15–20 double bond equivalence (DBE) were biodegraded into medium molecular weight compounds with 10–20 carbon atoms and ∼10 DBE. Contribution of lipids and unsaturated hydrocarbons compounds in DOM turned into 42.1% and 2.5%, respectively, while contribution of condensed aromatics in DOM dramatically increased to 15.4% in leachates along the A/O-MBR process. Most of DOM was converted into higher polymerization degree and accumulated in concentrated leachate (CL). Sulfur-containing compounds, whose relative peak ratio accounted for 56.4%, were regarded as recalcitrant DOM in CL. Increase of retention time in anaerobic unit for raw leachate might be useful for decomposing the long-chain organic compounds, which could also reduce loadings for the following A/O-MBR process. Well-focus techniques such as sulfur-oxidation bacteria could be introduced into the MBR unit for better removing organo-sulfur compounds. Advanced oxidation processes for CL degradation would be efficiency for the removal of recalcitrant DOM. Thus, leachate could be disposed in a zero-discharge way based on the practical experience of such a typical working treatment process.

Municipal solid waste (MSW) is one of the main anthropogenic greenhouse gas (GHG) emission sources. GHG emissions from the waste sector could rely on the disposal process greatly, and the corresponding GHG emission intensity (GHG emissions from per kg disposed MSW) might reflect the city’s waste management level. Shanghai, as the popular megacity in China, has witnessed the evolution of the waste disposal processes from landfill dominated to incineration dominated from 2005 to 2015, and the detailed GHG emission estimation was implemented combining the method recommended by IPCC and the bottom-up method. It was found that landfill contributed to 81.88% of total GHG emissions from 2005 to 2015, while the GHG emissions from incineration plants increased from 1.8 × 108 to 3.8 × 108 kg CO2-eq (CO2 equivalent) in the same period, with the amount of incinerated MSW increasing from 1.02 × 109 to 2.50 × 109 kg. The GHG emission intensity of the MSW management system reached 0.363 kg CO2-eq per kg MSW in 2012 but declined to 0.354 kg in 2015. And the GHG emission intensity of incineration was lower than that of landfill and composting, which fluctuated between 0.147 and 0.177 kg CO2-eq per kg MSW. Both the scale and the operation conditions of the waste disposal facilities could influence the GHG emission intensity. With the implementation of waste source sorting and incineration dominated in disposal processes, around 54.07% of GHG emissions could be reduced under the 2030 NP (New policy) scenario. GHG emission intensity could be employed as an indicator for waste disposal development levels.

The reduction in the fouling is an important way to maintain the steady operation for the nanofiltration (NF) process in leachate treatment. The fouling components from the real leachate treatment process were identified using a scanning electron microscope equipped with X-ray microanalysis (SEM-EDS), infrared spectroscopy (FTIR), atomic analysis and three-dimensional fluorescence (EEM) analysis, and the coagulation of Fe/Al/PAC was selected to reduce the potential pollutants in the leachate, to reduce the potential fouling. It was found that organic humic acid and calcium-magnesium precipitates were the main pollutants in NF fouling. The foulant layer was the result of the combination of organic matter, inorganic precipitation, colloids and microorganisms, and the colloids precipitation is more important, and should be removed in advance. PAC was found to be more efficiency to reduce the colloids and the inorganic matter, among the coagulants selection, with the chemical oxygen demand (COD) removal rate of 55.1%. The commercially available coagulant-poly aluminum chloride (PAC) was chosen as a coagulant. The removal rate of leachate reached 55.1%, and the flow rate through the membrane was increased by 35.8% under the optimum condition (pH was 5.0, PAC dosage was 100 mg/L, and the membrane pressure was 0.4 MPa). Through the pilot scale test, the effluent was connected to the microfiltration membrane and then to the nanofiltration membrane and the practical engineering application is feasible.

In this study, poly dimethyl diallyl ammonium chloride (PDADMAC) and polyacrylamide (PAM) were applied to substitute ferric trichloride (FeCl3) and lime conditioning for advanced dewatering of landfill sludge (LS). Four response surface methodology (RSM) models were constructed for FeCl3-lime, FeCl3-PAM, PDADMAC-lime and PDADMAC-PAM, and identical dosages, namely 29.86, 57.91, 5.73 and 2.99 mg/g dry solids (DS) for FeCl3, lime, PDADMAC and PAM, were obtained by solving the system of four RSM equations at water content of 60% to investigate conditioning mechanisms. Compared to FeCl3-lime, PDADMAC-PAM conditioning had strong charge neutralization and bridging performance, and obtained conditioned LS with large flocs size, strong network structure and rapid dewatering rate. By integrating RSM with nonlinear programming for optimization, the total cost of PDADMAC-PAM route was saved by 7.9% and close to FeCl3-lime, and the optimized condition with dosages of 1.93 and 3.47 kg/t DS was further confirmed by pilot-scale experiments. The results indicated that PDADMAC-PAM was a feasible substitute for FeCl3-lime in sludge conditioning, and showed more advantage if dewatered sludge was further treated by incineration.

Magnetite near-infrared (NIR) photocatalysts with upconversion properties are put forward to meet the requirements of high solar energy utilization efficiency and sustainability based on the resource utilization of electroplating wastewater (EPW). The Ca–Zn magnetite precursor (CZ) was initially prepared from the mixed-ferrites (M-Fe3O4) produced from EPW and the photocatalyst (Zn2+) and upconversion host material (Ca2+)-related metal ions included in EPW and its effluents. With the addition of lanthanides and F− ions, a novel magnetite NIR photocatalyst of Er3+/Tm3+/Yb3+-(CaF2/ZnFe2O4/ZnO) (ETY-FCZ) was further synthesized. In the crystal phases of ETY-FCZ, (Ca0.8Yb0.2)F2.2 is used as the upconversion host material for Er3+/Tm3+/Yb3+ ions. The magnetic agents including ZnFe2O4 display the heterojunction with ZnO, as well as the broadband spectrum utilization property for ETY-FCZ. ETY-FCZ possesses efficient electron-hole pair separation ability, and all the upconversion luminescence emitted from ETY-FCZ can be absorbed for photocatalysis, which result in higher removal rates of methyl orange and salicylic acid compared to those of CZ. ETY-FCZ is an excellent magnetite NIR photocatalysts with magnetic recycling performance, and it has promising applications in the reuse of EPW and the wastewater treatment.

The effects of nano zero-valent iron (NZVI) on sludge anaerobic digestion were investigated from the perspective of the sludge fermentation liquor (SFL) and microbial community structure. Compared with micrometer-scale ZVI, NZVI exhibited a considerable inhibition in methane production during the initial 6 days while the negative effect attenuated subsequently and methane production recovered. Similar to micrometer-scale ZVI, enhanced methane production (108.24 mL per gVS) was obtained with NZVI addition, and increased by 46.1% compared to no-ZVI assay. The results indicated that NZVI could promote hydrolysis-acidification with inhibited conversion of acetic acid to methane in the initial stage, which could be ascribed to the high H2 partial pressure. The rapid dissolution of NZVI hindered the phosphorus uptake by methanogens, meanwhile the more reductive atmosphere contributed to the degradation of propionic acid. Further investigations on SFL showed that NZVI could facilitate the release of biodegradable compounds without propionic acid accumulation, creating a favorable substrate environment for methanogens. The bacteria and archaea community structure involved in methane production was studied. Results indicated that NZVI could enhance hydrogenotrophic methanogenesis with the highest relative abundances of Clostridia (53.2%) and Methanosarcina (22.6%) among the assays.

To investigate the balance between volumetric methane production and substrate loading on anaerobic digestion (AD), long-term batch experiments were conducted at different total solids (TS) contents of 5% (R1), 10% (R2), 15% (R3) and 20% (R4), respectively. The results showed that maximum cumulative methane production (233 mL gVS−1) and VS removal efficiency (48.49%) was achieved in R1. Volatile fatty acids (VFAs) accumulation in R4 was 57.2% higher than that in R2 and 5.69 times higher than that in R1. Glucose degradation rate (GDR) for R3 and R4 declined fast indicating lower microbial activities than those in other two reactors. Microbial community analysis revealed that Coprothermobacter for proteins degradation and Methanosarcina for methanogenesis were enriched in R1 with relative abundance of 25.0% and 34.5%, respectively. Hydrogenotrophic methanogens was dominant in treatment of high-solid AD, in accordance with VFA accumulation. The assessment of methane production performance showed similar reactor utilization efficiency between R1 and R4.

The improvement of fluorite quality is an attractive measure to recover fluoride from high F− content wastewater and thus reduces the fluorite sludge generation rate, and the removal of contaminant pollutants could be helpful for the production of ceramic grade fluorite (>85%). In this work, typical etching wastewater was collected and characterized, and SO42− was found to be the main barrier for high quality CaF2 production, while CaSO4 could also contribute to CaF2 precipitation. The optimum SO42− content was adjusted by the introduction of barium salts, to keep a balance between the CaF2 quality and the settlement process. The ceramic grade CaF2 of 88% was obtained under the conditions: [Ca]/[F] of 1.29, pH 8.14 and Csulfate of 117.4 mg L−1. The residual SO42− content should be kept in the range of 100–130 mg L−1, and the formation of CaSO4, combined with CaF2 could accelerate the CaF2 precipitation by the co-precipitation method, with a larger particle size from 758 nm (without SO42−) to 898 nm. The gradient settlement of CaF2 contributes to the recovery of fluoride from etching wastewater, while CaF2 preparation should be carried out in a dynamic experiment, such as a fluidized bed, for further research.

Raf-1 kinase inhibitory protein (RKIP) is a critical molecule for cellular responses to stimuli. In this study, we investigated whether RKIP is responsible for neural cell apoptosis induced by oxygen-glucose deprivation (OGD) and explored the role of NF-κB and ERK pathways regulated by RKIP under OGD stimuli. RKIP was overexpressed or knocked down using lentivirus in PC12 cells, which were then challenged by OGD. RKIP overexpression significantly increased the cell viability of OGD cells, and attenuated apoptosis, cell cycle arrest, and reactive oxygen species generation. RKIP knockdown induced reverse effects. Moreover, we found that RKIP interacted with TAK1, NIK, IKK, and Raf-1 and negatively regulated the NF-κB and ERK pathways. RKIP overexpression significantly inhibited IKK, IκBα, and P65 phosphorylation in NF-κB pathway and MEK, ERK, and CREB phosphorylation in ERK pathway, respectively. RKIP knockdown induced reverse effects. Furthermore, a NF-κB inhibitor BAY 11-7082 and a MEK inhibitor U0126 blocked the changes caused by RKIP down-regulation after OGD. In conclusion, these results demonstrate that RKIP plays a key role in neural cell apoptosis caused by OGD partly via regulating NF-κB and ERK pathways. The present study may provide new insights into the role of RKIP in ischemic stroke.

Anaerobic digestion (AD) is considered an efficient method for sludge reduction and biogas generation simultaneously, while the excessive accumulation of volatile fatty acids (VFAs) often results in process instability in the thermophilic AD system. In this study, ferric chloride (FeCl3), as an additive, was supplemented into the sludge thermophilic AD system directly. A dosage gradient was adopted and 9.92 mg Fe per g DS was favorable for the disinhibition of VFAs, with the maximum methane production of 236.75 mL per g VS under the test conditions, which was 2.2 times higher than the control group. The results indicated that methane production could be successfully enhanced by disinhibiting the excessive VFAs. Further investigations of the composition of soluble organic compounds confirmed that acetic acid was the main inhibitor during the sludge thermophilic AD process, and was responsible for the acid inhibition. Meanwhile, dosing an appropriate amount of FeCl3 into the thermophilic AD system would contribute to acetic acid utilization for methane production, which should be attributed to the synthetic effects, except for the direct removal of acetic acid by Fe(OH)(CH3COO) precipitate. The dosage of FeCl3 in the thermophilic AD system showed significant impact on the process performance and certain dosages at low concentration (

Norfloxacin (NOR), a largely synthetized fluoroquinolone antibiotic, is frequently detected in aquatic environment and is resistant to conventional wastewater treatment process. In this study, a typical green technology, i.e., E+-ozonation, was employed and the effect of pH on NOR degradation was investigated. Two-pronged influences of pH were considered here, which were ionic forms of NOR and generation of reactive species. NOR0,- (pH 11) degradation rate for E+-ozonation in rapid stage reached 91.5%, which was much higher than NOR+,0 (pH 3, 57.9%) and NOR+,- (pH 7.8, 70.7%). The apparent rate constants for the degradation of NOR+,0, NOR+,-, and NOR0,- in rapid stage was 0.007, 0.011 and 0.022 s−1, respectively, as protonation of amine group presenting in the piperazinyl ring in NOR+,0 resulted in a decrease in its reactivity towards radicals. Obviously, •OH was greatly improved with the concentration of 5.7 × 10−5 mg/L at pH 11, which was twice higher than that generated at pH 3 due to cathodic O2 reduction. Cl− in the solution could be activated into ClO− and HClO from anode and reacted with •OH into Cl• and ClO• under alkaline conditions for further improving the oxidative ability in this system. In addition, twenty five transformation intermediates were identified altogether, but a significantly different pathways were perceived for the degradation of NOR with different ionic forms.

Spent bleaching earth (SBE) with high pollutant-producing coefficient was generated from lubricating oil refining and aviation kerosene hydrogenation unit in the oil refinery, while the disposal processes were limited due to its hazardous properties in the city. A simple and efficient approach was developed to co-combust SBE and coal in the company inner power plant, and synergetic effect was observed in SO2 and NOx reduction in flue gas and energy recycling of waste oil. The full-cycle combustion process was investigated in details under different mixing ratio of the two substances from 0 to 1000 °C. According to the TG/DSC-MS results, it was found that the introduction of SBE could reduce the decomposition temperature of coal from 475-931 °C to 450–815 °C, since the dehydrogenation and decarboxylation effects of metallic oxides and the high contacting area with oxygen provided by the porous structures of SBE. The tubular electric heating furnace-FTIR results showed that the concentration of typical pollutants in flue gas decreased obviously at the coal/SBE mixing ratio 5:1, among them, the maximum SO2 emissions reduction reached 32%. The chemical adsorption effect of alkaline earth metals and transition metal oxides and oxidation-reduction reaction between NO+NO3− and SO32− were proved as the main fixation mechanisms. The regenerated porous structures in SBE provide new adsorption site after the volatilization of adsorbed oils, so as to further enhance the fixation capacity. Co-combustion process of SBE and coal offered a promising way for simultaneous in-situ gaseous pollutant control in flue gas and energy recycling from SBE.

Oil refinery sludge is a complex mixture of hydrocarbons, water and sediments produced in the refining process, which is classified as a hazardous waste. The source reduction of sludge is inhibited by the combination of total petroleum hydrocarbons (TPH) and solid particles, and the decomposition of TPH is a critical step for oily sludge (OS) disposal. Microbubble ozonation was introduced to improve the efficiency for TPH removal in this work. 70.9% of TPH was found to be decomposed from OS with the initial pH of 3, ozone dosage of 0.27 gO3/gTS and total solid of 2% in 120 min. The corresponding reaction rate constant k for the rapid stage reached 0.0269 min−1, two times higher than the control system of macrobubble ozonation. The synergistic effect of oxidation and flotation was observed in the microbubble system by destroying the chemical bonds between petroleum hydrocarbons and particle surface and improving the adhesion probability between microbubbles and oily flocs. A broad-spectrum removal rate of 71.7–79.5% was observed for the middle or long chain hydrocarbons fractions (nC7-C10, nC11-C20, nC21-C30 and nC31-C40) in TPH. Most of heavy hydrocarbons (nC21-C40) in OS were oxidized and decomposed to the low boiling point hydrocarbons according to thermogravimetric results. The principal intermediates included 42.6% carboxylic acids, 18.8% phenolics and 13.9% alcohols and other gaseous byproducts. Microbubble ozonation is expected to be the first step for detoxification and decomposition of OS, thus reducing the generation of hazardous wastes.

Facile and large-scale preparation of upconversion photocatalyst films is promising for the degradation of volatile organic compounds (VOCs), major component of the landfill gas stench. Herein, a spin-assisted layer-by-layer coating method is explored to fabricate the upconversion photocatalyst film of polyethylene terephthalate (PET)/Tm/Yb-doped NaYF4 (TYN)/P25/(CdSe/CdS) QDs (PET/TYN/P25/QDs). The near-infrared light energy passes through the top QDs and P25 layers to excite TYN, and the strong upconversion emissions of UV (290, 346, and 362 ​nm) and visible (452 and 476 ​nm) light are produced and absorbed by P25/QDs for photocatalysis. In the photocatalytic degradation of gaseous toluene, the removal efficiency over the PET/TYN/P25/QDs film reaches 83% after 1 ​h of simulated sunlight irradiation, which is much higher than that (40%) of the PET/TYN/P25 film. This better photocatalytic activity is ascribed to the large absorption edge of the CdSe/CdS QDs and the efficient electron-hole pair separation in the QDs-P25 heterostructure.

Dewaterability of waste activated sludge was significantly improved through a mild conditioning process without energy-intensive treatment. Calcium nitrate (Ca(NO3)2) addition enhanced sludge dewatering performance, with a reduction in capillary suction time (CST) and cake moisture content by 58.7% and 8.5%, respectively. Ca(NO3)2 treatment outperformed KNO3 and CaCl2 treatment by 59.1% and 6.5% regarding reduction in cake moisture content. Characterization of the sludge extracellular polymeric substances (EPS) revealed that proteins in the slime EPS (S-EPS), loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) were decomposed by 97.7%, 89.6% and 60.9%, respectively, during the 5-day denitrification process triggered by nitrate supply, thus releasing bound water. Ca2+ addition induced charge neutralization of negatively-charged EPS functional groups and also facilitated flocculation, further enhancing the sludge filterability. This study also showed a proof-of-concept that nitrate brine (i.e. concentrated nitrification effluent) could be used to enhance sludge dewatering, which might provide a new paradigm of efficient sludge reduction for local municipal wastewater treatment facilities.