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A battery of agricultural straw derived biomass activated carbons supported LaOx modified MnOx (LaMn/BACs) was prepared by a facile impregnation method and then tested for simultaneous abatement of NO and Hg0. 15%LaMn/BAC manifested excellent removal efficiency of Hg0 (100%) and NO (86.7%) at 180 °C, which also exhibited splendid resistance to SO2 and H2O. The interaction between Hg0 removal and NO removal was explored; thereinto, Hg0 removal had no influence on NO removal, while NO removal preponderated over Hg0 removal. The inhibitory effect of NH3 was greater than the accelerative effect of NO and O2 on Hg0 removal. The physicochemical characterization of related samples was characterized by SEM, XRD, BET, H2-TPR, NH3-TPD, and XPS. After incorporating suitable LaOx into 15%Mn/BAC, the synergistic effect between LaOx and MnOx contributed to the improvement of BET surface area and total pore volume, the promotion of redox ability, surface active oxygen species, and acid sites, inhibiting the crystallization of MnOx. 15%LaMn/BAC has the best catalytic oxidation activity at low temperature. That might be answerable for superior performance and preferable tolerance to SO2 and H2O. The results indicated that 15%LaMn/BAC was a promising catalyst for simultaneous abatement of Hg0 and NO at low temperature.

Impregnating CuCl2 on AC (activated coke) support to synthesize xCuCl2/AC showed superior activity with higher 90% Hg0 removal efficiency at 80–140 °C, as well as a lower oxygen demand of 2% O2 for Hg0 removal. The acceleration on Hg0 removal was observed for NO and SO2. The BET, SEM, XRD, XPS, TPD, and FT-IR characterizations revealed that the larger surface area, sufficient active oxygen species and co-existence of Cu+ and Cu2+ may account for the efficient Hg0 removal. In addition, the low demand of gaseous O2 was contributed to higher content of active oxygen and formed active Cl. After adsorbing on Cu sites, Cl sites, and surface functional groups, the Hg0(ads) removal on xCuCl2/AC was proceeded through two ways. Part of Hg0(ads) was oxidized by active O and formed Hg0, and the other part of Hg0 combined with the active Cl, which was formed by the activation of lattice Cl with the aid of active O, and formed HgCl2. Besides, the Hg2+ detected in outlet gas through mercury speciation conversion and desorption peak of HgCl2 and Hg0 further proved it. As displayed in stability test and simulated industrial application test, CuCl2/AC has a promising industrial application prospect.

A series of CoOx modified MnOx/biomass activated carbons (CoMn/BACs) prepared by the ultrasound-assisted impregnation method were employed for the simultaneous removal of NO and Hg0 from simulated coal-fired flue gas for the first time. The physicochemical properties of such samples were characterized by XRD, BET, SEM, TEM, NH3-TPD, H2-TPR, FTIR, TG and XPS. 15%CoMn/BAC exhibited preferable performance for NO and Hg0 removal in a wide temperature range from 160 to 280 °C, and it yielded prominent NO removal efficiency (86.5%) and superior Hg0 removal efficiency (98.5%) at 240 °C. The interaction between NO removal and Hg0 removal lessened corresponding separate efficiency, the adverse effect of NH3 on Hg0 removal could not be offset by promotional influences of NO and O2. Compared with 15%Mn/BAC, the addition of CoOx with suitable amount into 15%CoMn/BAC could contribute to the synergistic effect between MnOx and CoOx, resulting in the increase of BET surface area and surface active oxygen species as well as Mn4+ concentration, the enhancement of redox ability and the strength or amount of surface acid sites, restraining the crystallization of MnOx, which might be responsible for the improvement of catalytic performance and resistance to SO2 and H2O. Additionally, the hydrophobic property of BAC further strengthened H2O tolerance. The results of stability and recyclability tests indicated that 15%CoMn/BAC possessed a promising application potential for NO and Hg0 simultaneous removal at low temperature.

MoO3-CeO2/cylindrical activated coke samples (MoCeY/AC) synthesized by an impregnation method were employed to investigate elemental mercury (Hg0) removal at 60–210 °C from simulated flue gas without HCl. MoCe0.5/AC with an optimal Mo/Ce molar ratio of 0.5 exhibited an excellent Hg0 removal efficiency (94.74%) at 120 °C, as well as good stability and prominent resistance to SO2 and H2O. The physicochemical property of the samples and the Hg0 removal mechanism were discussed by ICP-AES, SEM, EDX, BET, XRD, H2-TPR, XPS and Hg-TPD. The results of characterizations showed that MoCe0.5/AC possessed the special petal-like outer microstructure, large BET surface area, well-dispersed metal oxides and high reducibility, which was conducive for Hg0 removal. Furthermore, the synergistic effect between Mo6+ and Ce3+ was favorable to the high Hg0 removal performance by providing high valence Ce. According to the Hg-TPD tests, the chemisorption of Hg0 was a major approach for Hg0 removal, while physisorption and catalytic oxidation were just accounted for a tiny fraction. Moreover, the chemisorbed mercury could be validly distinguished into weakly-HgO, strongly-HgO, Oα-HgO and HgSO4 (when SO2 was added). Compared with raw AC, MoCe0.5/AC could enhance the Hg0 oxidation performance and produce Oα-HgO during the Hg0 removal process. In addition, the possible reason for the high SO2 tolerance of MoCe0.5/AC was examined: (i) the preferential combination between sulfate and MoO3 could protect CeO2 for Hg0 removal; (ii) SO2 could contribute to the formations of weakly-HgO and HgSO4. Finally, the regenerability of MoCe0.5/AC was also discussed.

MnxCoy/Zrz-AC prepared by impregnation method was investigated on the simultaneous removal of HCHO and Hg0. The samples were characterized by BET, SEM, XRD, H2 pulse chemisorption, H2-TPR, XPS, Hg-TPD and in-situ DRIFTS. Thereinto, the optimal Mn2/3Co8/Zr10-AC achieved 99.87% HCHO removal efficiency and 82.41% Hg0 removal efficiency at 240 °C, respectively. With increased surface area and pore volume, Zr-AC support facilitated higher dispersion of MnOx-CoOx. Moreover, the co-doping of MnOx-CoOx endowed the sample with more active oxygen species and higher reducibility, which further facilitated the removal of HCHO and Hg0. Chemisorption was proved to predominate in Hg0 removal, and oxidation also worked as Hg2+ was detected in outlet gas. Besides, HCHO predominated in the competition of active oxygen species, especially for lattice oxygen, thus suppressed the Hg0 removal. According to in-situ DRIFTS, HCHO removal proceeded as HCHOads → DOM → formate species → CO2 + H2O, and was boosted by active oxygen species. Furthermore, Mn2/3Co8/Zr10-AC was proved with excellent regeneration performance, indicating its potential in practical application.

This study investigated the clean properties and combustion behavior of hydrochar from food waste (FW). The hydrochar was characterized by proximate analysis and HHVs, and the chemical forms were investigated by FTIR, XPS (Sulfur), and XANES (Chlorine). TG-FTIR was used to assess the combustion behaviors, and XRF was used to assess the fouling and slagging inclinations. Results showed that increasing temperature from 180 °C to 260 °C enhanced the removal of N, S, and Cl for hydrochar. Especially, aromatic-S and sulfate-S increased in contrast to sulfoxide-S, and more inorganic-S was produced in hydrochar; all samples had mainly inorganic-chlorine. Additionally, the release of HCl, SO2, and NO of hydrochar combustion were significantly reduced and the SI and FI index decreased to ranges of 0.18–0.16 and 0.32–0.17, respectively. However, hydrochar produced at temperature above 220 °C led increased NO emission possibly due to formation of more pyridine-N and quaternary-N.

This work had demonstrated a novel and high-efficiency perchlorate reduction particle electrode using benzalkonium chloride as dynamics strengthener and coupling with rhenium (Re) and palladium (Pd) nanoparticles (Re-Pd/BC). Perchlorate ions could be rapidly adsorbed in the presence of benzalkonium chloride, facilitating its subsequent reduction on the Re-Pd/BC particle electrode. On the basis of the characterization results and kinetics analysis, a synergistic effect of Re and Pd was observed, perchlorate could be efficiently reduced and completely converted into chlorine in optimized conditions (pH 3.0, anaerobic and current density 20 mA/cm2) and the reduction rate constant of Re-Pd/BC was 0.9451 L−1 gcat−1. The superfluous oxygen in solution could lead to Re-Pd/BC deactivation, and increased current density was beneficial of electro-reduction. The increased pH lead to decrease of reduction efficiency, and the coexisting anion of nitrate could be competed with perchlorate for reduction sites which lead to decrease of reduction rate. Based on the experimental results, it was found that the existing form of Re and Pd on the surface of Re-Pd/BC, the number of atomic H∗ and current density played an important role in perchlorate electro-reduction process.

To rationally utilize agricultural wastes and expediently simultaneous control of elemental mercury (Hg0) and NO, a series of CoOx-CeO2 loaded maize straw derived biomass activated carbon (CoCe/BAC) samples were applied for simultaneous NO and Hg0 removal. These samples’ physicochemical characteristics were characterized by BET, SEM, XRD, NH3-TPD, H2-TPR, XPS and FTIR. 15%Co0.4Ce0.6/BAC yielded prominent Hg0 removal efficiency (96.8%) and superior NO removal efficiency (84.7%) at 230 °C. The separate or synchronous deactivation effects of 400 ppm SO2 and 5%H2O were detected. The interaction between NO removal and Hg0 removal was investigated, the results demonstrated that abundant Hg0 exhibited very slightly inhibitory effect on NO removal, and NH3 negatively affected Hg0 removal, whereas NO mildly boosted Hg0 removal in presence of O2. The characterization analyses indicated the excellent performance of 15%Co0.4Ce0.6/BAC could be ascribed to its better texture properties, lower crystallinity and stronger redox ability. Besides, a synergetic effect appeared between cobalt oxide and cerium oxide, resulting in generating more Ce3+ and Co3+ to induce more anionic defects and produce more active oxygen and oxygen vacancies. The removal mechanisms of NO and Hg0 were systematically investigated, and NO reduction reactions were mainly assigned to the Langmuir-Hinshlwood mechanism while both adsorption and Hg0 oxidation contributed to Hg0 removal. Meanwhile, Hg0 oxidation corresponded to the Mars-Masson mechanism prevailed gradually with the increase of reaction time.

Phosphorus is a nutrient that is essential to nature and human life and has attracted attention because of its very limited reserves. Dwindling phosphorus reserves and soaring prices have made the recovery of phosphorus from waste biosolids even more urgent. Waste activated sludge, as the final destination of most of the phosphorus in human domestic and industrial water, has been considered as a reliable source of phosphorus recovery. The thermal treatment method of sewage sludge is currently a relatively environmentally friendly disposal method, which mainly includes incineration, pyrolysis and hydrothermal carbonization. This paper reviews the methods for the recovery of different forms of phosphorus (wet chemical, thermochemical and electrodialysis) from solid products obtained from different sludge thermal treatment methods (incinerated sewage sludge ash, pyrolysis of sewage sludge char and hydrochar) and the bioavailability of the recovered phosphorus products. Incineration of sewage sludge is currently the most established and effective method for recovering phosphorus from the thermal treatment products of sewage sludge. One of the wet chemical methods has been applied on a commercial scale and is expected to be further developed for future industrial applications. Pyrolysis and hydrothermal carbonation still have many research gaps in this field. Based on their principles and laboratory performance, both of them have the potential to recover phosphorus and should be further explored.

Perchlorate is the main contaminant in surface water and groundwater, and it is of current urgency to remove due to its high water solubility, mobility, and endocrine-disrupting properties. The conversion of perchlorate into harmless chloride ions by using appropriate catalysts is the most promising and effective route to overcome its high activation energy and kinetic stability. Perchlorate is usually reduced in two ways: (1) indirect reduction via oxygen atom transfer (OAT) reaction or (2) hydrodeoxygenation through highly active reducing H atoms. This paper discusses the mechanisms underlying both the OAT reaction catalyzed by homogenous rhenium-oxo complexes or biological Mo-based enzymes and the heterogeneous hydrogenation for perchlorate reduction. Particular emphasis is placed on the factors affecting the catalytic process and the synergy between the (1) and (2) reactions. For completeness, the applicability of different electrolysis devices, electrodes, and bioreactors is also illustrated. Finally, this article gives prospects for the synthesis and application of catalysts in different pathways.

A series of low-cost Cu-Mn-mixed oxides supported on biochar (CuMn/HBC) synthesized by an impregnation method were applied to study the simultaneous removal of formaldehyde (HCHO) and elemental mercury (Hg0) at 100–300° C from simulated flue gas. The metal loading value, Cu/Mn molar ratio, flue gas components, reaction mechanism, and interrelationship between HCHO removal and Hg0 removal were also investigated. Results suggested that 12%CuMn/HBC showed the highest removal efficiency of HCHO and Hg0 at 175° C corresponding to 89%and 83%, respectively. The addition of NO and SO2 exhibited inhibitive influence on HCHO removal. For the removal of Hg0, NO showed slightly positive influence and SO2 had an inhibitive effect. Meanwhile, O2 had positive impact on the removal of HCHO and Hg0. The samples were characterized by SEM, XRD, BET, XPS, ICP-AES, FTIR, and H2-TPR. The sample characterization illustrated that CuMn/HBC possessed the high pore volume and specific surface area. The chemisorbed oxygen (Oβ) and the lattice oxygen (Oα) which took part in the removal reaction largely existed in CuMn/HBC. What is more, MnO2 and CuO (or Cu2O) were highly dispersed on the CuMn/HBC surface. The strong synergistic effect between Cu-Mn mixed oxides was critical to the removal reaction of HCHO and Hg0 via the redox equilibrium of Mn4+ + Cu+ ↔ Mn3+ + Cu2+.

To investigate hydrochar as a soil amendment for the immobilization of Cd, the characteristics of hydrochars (HCs) under three temperatures and residence times, were studied, with a particular interest in soil properties, as well as the speciation, availability and plant uptake of Cd. HCs were obtained by a hydrothermal carbonization (HTC) reaction of sewage sludge (SS). Based on the study of HC properties, we found that HCs present weak acidity with relatively high ash content and low electrical conductivity (EC) values. The addition of HCs to soil decreased soil pH and EC values but increased the abundance of soil microorganism. HCs also promoted the transformation of Cd from unstable to stable speciation and can decrease the content of phyto-available Cd (optimum condition and efficiency: A13, 2 15.38%), which restrained cabbage from assimilating Cd from soil both the aboveground (optimum condition and efficiency: A35, 52.29%) and underground (optimum condition and efficiency: C15, 57.53%) parts of it.

To optimize simultaneous control of NO and elemental mercury (Hg0) and gain more insight into the mechanisms, nano-sized TiO2-Al2O3-CeO2 materials synthesized via sol-gel method were used for simultaneous removal of NO and Hg0 from simulated flue gas. The physicochemical characteristics of catalysts were characterized by ICP-OES, BET, XRD, SEM, TEM, XPS, H2-TPR and FT-IR. TiAl10Ce20 nanoparticle with the addition of 10 wt%Al2O3 showed superior NO removal efficiency (93.41%) and Hg0 removal efficiency (80.54%) in the presence of SCR atmosphere at 300 °C. The deactivation effects of 8% H2O and 400 ppm SO2 were also reduced by Al addition. In the presence of SCR atmosphere, the capture of Hg0 was inhibited by the existence of NH3, while the presence of Hg0 had little impact on NO removal. The characterization results showed that the excellent performance of TiAl10Ce20 nanoparticle might result from the stronger redox ability, lower crystallinity and better texture properties with highly dispersed Ce species, which were all attributed to Al addition. The mechanisms for simultaneous removal of NO and Hg0 were also proposed on the basis of above results. TiAl10Ce20 nanoparticle developed in this work was considered to be a promising catalyst for simultaneous removal of NO and Hg0.

It is necessary to control the emissions of toluene, which is hazardous to both human health and the atmosphere environment and has been classified as a priority pollutant. Manganese oxide-based (Mn-based) catalysts have received increased attention due to their high catalytic performance, good physicochemical characteristic, availability in various crystal structures and morphologies, and being environmentally friendly and low cost. These catalysts can be classified into five categories, namely single manganese oxide, Mn-based composite oxides, Mn-based special oxides, supported Mn-based oxides, and Mn-based monoliths. This review focused on the recent progress on the five types of Mn-based catalysts for catalytic removal of toluene at low temperature and further systematically summarized the strategies improving catalysts, including improving synthetic methods, incorporating MnOx with other metal oxides, depositing Mn-based oxides on proper supports, and tuning the supports. Moreover, the effect of coexisting components, the reaction kinetics, and the oxidation mechanisms toward the removal of toluene were also discussed. Finally, the future research direction of this field was presented.

In this study, hydrothermal carbonization (HTC) of sewage sludge(SS) was carried out at a temperature of 270℃ and a resulting pressure of 7–9 MPa with 2 h. The effect of feed water pH values in the range of 2–12 on hydrochar characteristics, organic component and thermal behavior was evaluated. The result shows that with the pH value increasing, ash content shows a trend of decline, and organic components in the hydrochar become significantly simpler than SS. hydrochar is more beneficial to produce a fatty substance during an acidic environment and alkaline environments favor the formation of N-containing organic compounds and ketone organics, especially in strongly alkaline environments. Compared to the SS, hydrochar burning interval shortened 100℃ and the combustion of hydrochar is more durable. Considering the organic composition and combustion performance of hydrochar, it is found that the hydrochar prepared under 270-5 condition has the best effect.

In this study, Fe(II)-activated persulfate-assisted hydrothermal treatment (Fe(II)-PS-HT) was used to improve the efficiency of removing nitrogen (N) from the sewage sludge (SS) under relatively mild conditions (i.e., at 150 °C, for 20min), and the N transformation mechanism was investigated. The total N content in the solid residue was used to evaluate the N removal efficiency. Further, the redistribution of N in the solid and liquid products was characterized and quantified to obtain a N transformation mechanism during sequential persulfate oxidation (Fe(II) and persulfate) assisted hydrothermal treatment (HT). The experimental results denote that the N removal efficiency obtained from the Fe(II)–PS–HT (persulfate/C = 0.085 and Fe(II)/persulfate = 0.5) treated SS was increased by 35.0% at a relatively mild temperature (i.e., 150 °C) when compared with that obtained by treating SS using normal HT. Elevating Fe(II)/persulfate ratio to 1.25 promoting the N removal efficiency by 59.9%–65.9%. Furthermore, the electron paramagnetic resonance (EPR) and scanning electron microscopy (SEM) results clearly denote a N removal mechanism where the sulfate radicals (SO4∙-) produced by Fe(II)-PS destroy the sludge structure and destructed extracellular polymers (EPS). In the absence of EPS protection, proteins were directly exposed to extreme hydrothermal circumstances, and were rapidly transformed from the SS into the liquid residue. The free radicals also provided energy for the denitrification of Heterocycle-N. Consequently, a high N removal efficiency was obtained by Fe(II)-PS-HT with persulfate/C = 0.085 and Fe(II)/persulfate = 1.25 at 150 °C for 20 min.

In this work, functional mesoporous bean dregs-based biochar electrodes were prepared by electrophoretic deposition for perchlorate (ClO4-) electro-sorption. We characterized the textural and electrochemical properties of the biochar and determined the kinetics of electro-adsorption. The results show that 15% concentration of ZnO nanoparticle modification is recommended to increase the mesoporous volume, specific surface area, hydrophilicity and conductivity of biochar materials. After betaine functionalization, the obtained biochar (BK-Z15%-N) possesses an excellent electrochemical performance with high current density, charging capacity, and low ohmic impedance. As expected, it presents an electro-adsorption capacity of 28.31 mg g-1 toward 20 mg L-1 ClO4- at 1 V, which is four times higher than that without voltage and much better than other electrodes in this study and most reported data. The electro-adsorption of ClO4- on BK-Z15%-N electrode fits the fractal model, which is a complex process controlled by the electrical force and independent of solution pH. BrO3- and Cl- are the most competitive anion to ClO4- electro-sorption. Notably, it maintains a sustainable electrochemical regeneration ability due to the reversible redox activity of quaternary amine groups. Therefore, this study offers a remarkable and reliable method for improving the electro-sorption performance of perchlorate.

The influences of SO2 on Hg° removal over the 1V-8Ce/AC sorbent were systematically investigated at low temperatures. The experimental results showed that SO2 has a dual effect on Hg° removal, that is, SO2 has both a promoting effect and an inhibiting effect on Hg° removal. The SO2 transient response experiment indicated that SO2 could not only react with Hg° to promote the removal of Hg° but also react with the active components and poison the sorbent. O2 is indispensable for the removal of Hg°, which can offset the adverse effects caused by SO2 and H2O. HCl exhibited an obvious promoting effect on Hg° removal in the presence of SO2. The 1V-8Ce/AC sorbent exhibited good sulfur resistance and excellent stability (EHg = 90.04 %) after a 24 h reaction performed under the 1000 ppm SO2 condition at 150 °C. In addition, the Hg-TPD and XPS methods were used to assist in studying the effect of SO2 on Hg° removal over the 1V-8Ce/AC sorbent. Finally, the mechanism of Hg° removal in an SO2 atmosphere was also explored, which showed that Hg° was removed by two possible pathways over the 1V-8Ce/AC sorbent.

To remove gaseous formaldehyde (HCHO) and rationally utilize agriculture wastes, chemical activation method using ZnCl2 as activating agent was employed to develop high-class biomass activated carbons (BACs) derived from agricultural straws for HCHO removal at ambient temperature. Proximate analysis and ultimate analysis testified that these agricultural straws were appropriate BACs precursors. BACs’ physicochemical properties were characterized by BET, SEM, FTIR and TGA, which demonstrated BACs with large specific surface area had the potential as ideal adsorbents. Systemic tests investigated the effects of activating agent (ZnCl2) and the concentrations of O2 and HCHO on adsorption performances of BACs, and compared them with two commercial activated carbons (CACs). Results showed ZnCl2 brought enormously positive effects but O2 had a prohibitive effect on the adsorption performance. BACs exhibited better performance than CACs, and BACM (BAC derived from maize straw) could obtain more than 80% removal efficiency under 1ppm HCHO after 40h. Desorption and regeneration tests were conducted to evaluate the security of the adsorbent and recycle regenerated adsorbent. The desorption temperature all above 50°C could ensure use security indoors. Saturated BACM through 1 or 2 run regeneration still exhibited better adsorption performance compared with virgin CAC from coal, indicating that the regeneration was significantly meaningful in practical application.

A series of Mn–Ni/AC (AC, activated coke) catalysts were synthesized by the impregnation method for the removal of elemental mercury (Hg0) from simulated flue gas. The samples were characterized by BET, ICP-OES, SEM, XRD, XPS, H2-TPR, FT-IR, and TGA. Mn6Ni0.75/AC exhibited optimal removal efficiency of 96.6% in the condition of 6% O2 and balanced in N2 at 150 °C. The experimental results showed that both O2 and NO facilitated Hg0 removal. SO2 could restrain the Hg0 removal in the absence of O2, while the inhibitory effect of SO2 was weakened with the aid of 6% O2. In addition, H2O exhibited a slightly negative influence on Hg0 removal. The characterization of the samples indicated that Mn6Ni0.75/AC possessed larger specific surface area, higher dispersion of metal oxides, and stronger redox ability. In the meantime, the results of XPS and FT-IR demonstrated that the lattice oxygen and chemisorbed oxygen made contributions to Hg0 removal and the consumed oxygen could be compensated by the redox cycle of metal oxides and gas-phase O2. Meanwhile, the mechanisms of Hg0 removal were proposed based on the above studies.

To provide insight into optimizing flue gas treatment, simultaneous removal of elemental mercury (Hg0) and NO using a CeO2 modified V2O5–WO3/TiO2 catalyst was investigated. The results show that a novel V2O5–WO3/TiO2–CeO2 catalyst exhibits excellent Hg0 oxidation efficiency (88%) and NO conversion efficiency (89%) at 250 °C. Furthermore, CeO2 modified V2O5–WO3/TiO2 not only exhibits enhanced catalytic activity but also good resistance in SO2 and H2O. These catalysts were also characterized using BET, SEM, XRD, XPS, and H2-TPR. We found lower crystallinity, more reduced species and better texture properties to be presented, which were all ascribed to CeO2 doping. Also, the redox cycle (V4+ + Ce4+ ↔ V5+ + Ce3+) plays a key role in promoting Hg0 oxidation and NO conversion. In tune with the experimental results, a mechanism for the simultaneous removal of Hg0 and NO was proposed for the V2O5–WO3/TiO2–CeO2 catalysts.

Fe2O3 and CeO2 modified activated coke (AC) synthesized by the equivalent-volume impregnation were employed to remove elemental mercury (Hg(0)) from simulated flue gas at a low temperature. Effects of the mass ratio of Fe2O3 and CeO2, reaction temperature, and individual flue gas components including O2, NO, SO2, and H2O (g) on Hg(0) removal efficiency of impregnated AC were investigated. The samples were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Results showed that with optimal mass percentage of 3 % Fe2O3 and 3 % CeO2 on Fe3Ce3/AC, the Hg(0) removal efficiency could reach an average of 88.29 % at 110 °C. Besides, it was observed that O2 and NO exhibited a promotional effect on Hg(0) removal, H2O (g) exerted a suppressive effect, and SO2 showed an insignificant inhibition without O2 to some extent. The analysis of XPS indicated that the main species of mercury on used Fe3Ce3/AC was HgO, which implied that adsorption and catalytic oxidation were both included in Hg(0) removal. Furthermore, the lattice oxygen, chemisorbed oxygen, and/or weakly bonded oxygen species made a contribution to Hg(0) oxidation.

This study was performed to investigate the concentration and the health risk of heavy metals (HMs: Zn, Pb, Cd, Ni, Fe, Mn, Cr and Cu) in size-segregated airborne particulate matter (APM). APM samples were collected into 9 size fractions (>9.0 μm, 5.8-9.0 μm, 4.7-5.8 μm, 3.3-4.7 μm, 2.1-3.3 μm, 1.1-2.1 μm, 0.7-1.1 μm, 0.4-0.7 μm

To study the simultaneous removal of Sulfur Dioxide (SO2) and Nitrogen Oxides (NOx) from simulated flue gas by wet method, a bubbling device containing calcium hypochlorite (Ca(ClO)2) solution was used in the experiments. In the first place, thermodynamic analysis was conducted to determine the depth of reaction process, and the reaction mechanism of desulfurization and denitration was proposed. After that, experimental results exhibited that SO2 could be removed by Ca(ClO)2 solution completely while the removal efficiency of NOx was 41.2%. Moreover, on the basis of high SO2 removal efficiency, the effects of various factors on the removal efficiency of NOx, such as: the height of liquid layer, Ca(ClO)2 concentration, reaction temperature, initial pH value, O2 percent, SO2 concentration, and additives were investigated, respectively. Finally, simultaneous removal of SO2 and NOx under the optimized conditions were investigated, SO2 removal efficiency of 100% and NOx removal efficiency of 85.9% were achieved. The analysis of reaction products indicated that the main anions in the liquid phase were SO42- and NO3−. © 2015 American Institute of Chemical Engineers Environ Prog, 34: 1586–1595, 2015

In this article, a new briquette fuel (SC), which was produced by the mixture of coal fines (25.9%), sewage sludge (60.6%), lignin (4.5%), tannic acid (4.5%) and elemental silicon (4.5%), was provided. Then, in a high temperature electric resistance tubular furnace, the total emissions of NO2 and NO, effects of combustion temperature, air flow rate and heating rate on NOx (NO, NO2) emissions of SC were studied during the combustion of SC; furthermore, effects of additives on hardness were also analysed, and the X-ray photoelectron spectroscopy was applied to investigate the reduced NOx emission mechanism. The research results showed that, compared with the characteristics of briquette fuel (SC0) produced only by the mixture of coal and sewage sludge (the ratio of coal to sewage sludge was the same as that of SC), the Meyer hardness of SC was 12.6% higher than that of SC0 and the emissions of NOx were 27.83% less than that of SC0 under the same combustion conditions. The NOx emissions of SC decreased with the adding of heating rate and increased with the rise of air flow rate. When the temperature was below 1000 °C, the emissions of NOx increased with the elevated temperature, however, further temperature extension will result in a decreasing in emissions of NOx. Furthermore, the X-ray photoelectron spectroscopy results proposed that the possible mechanism for the reduction of NOx emissions was nitrogen and silicon in SC to form the compounds of silicon and nitrogen at high temperatures.

As a newly emerging persistent environmental contaminant, perchlorate (ClO4 −) has adverse effects on thyroid function by inhibiting iodide uptake and could result in neurodevelopment deficits. Our study was performed to investigate the concentration of perchlorate in size-segregated airborne particulate matter (APM) and evaluate its human exposure for children and adults. In this study, 45 size-segregated APM samples were collected from Changsha, China, during July 20 to July 31, 2016. The total APM concentrations ranged from 93.367 to 253.271 μg/m3 (mean 154.651 ± 59.175 μg/m3), and a bimodal size distribution was observed during the sampling period. The concentrations of perchlorate in size-segregated APM were in the range of 0.05–4.99 ng/m3 (mean 2.03 ng/m3). Exposure evaluation indicated that the ingestion was the predominant exposure pathway for daily intake of perchlorate via size-segregated APM, and children are more likely to intake more perchlorate via APM than adults. We suggested that the risk of exposure to perchlorate for children is worthy of attention, and a further study is required, especially for seasonal variations.

The probable sources and potential ecological risks of Cu, Zn, Cd and Pb in PM2.5 in Changsha were analyzed. The intelligent medium-flow total suspended particle sampler was used to collect the PM2.5 samples from Yuelu (YL), Kaifu (KF), and Yuhua (YH) districts of Changsha in March-April of 2013. The total concentration of heavy metals (HMs) in PM2.5 was used for source identification by correlation coefficients and principal component analysis (PCA). Otherwise the potential ecological risks indices (RIs) were calculated based on the bioavailable fractions of HMs which were obtained through BCR sequential extraction. Almost 50% of Cu, Cd and Pb in PM2.5 of all sites were accumulated in soluble and reducible fractions by speciation analysis. The correlation coefficients and PCA analysis showed that HMs in PM2.5 of Changsha in spring were mainly from vehicular emissions, fuel combustion, resuspension of dust and other pollution sources. The average potential ecological RIs of HMs in PM2.5 of Changsha were 6193.80 which suggests that HMs in PM2.5 was extremely serious. These results would be a good reference for health studies and formulation of environmental regulations.

The fate and risk assessment of heavy metals (HMs) in solid residue from co-liquefaction of sewage sludge (SS) and Camellia oleifera cake (COC) in supercritical ethanol (SCE) were investigated. SCE effectively stabilized HMs in solid residues and a better stabilization was presented on Zn than Cd. Moreover, SCE significantly transformed Cd, Cu and Zn into F4, which reduced the risk to the environment. Furthermore, risk assessments of Igeo, E r i , RI and RAC demonstrated that the addition of COC was beneficial to the contamination decrement of HMs since pollution levels of HMs all decreased after treatment, and the lowest pollution level was obtained with SC-350. Therefore, SS treated by SCE with the addition of COC could be a promising technology for disposal of SS, especially considering the safety of COC as regards HMs problem.

The catalytic performances of catalysts with binary-oxides supports in selective catalytic reduction (SCR) of NO by NH3 were studied. Binary metal oxides supports γ-Al2O3–SiO2, γ-Al2O3–TiO2, and γ-Al2O3–ZrO2 were prepared by hydrolyzation and coprecipitation methods, after that MnOx–CeOy was loaded using isovolumetric impregnation method. Characterizations for the samples involved N2 adsorption–desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H2 temperature programmed reduction (H2-TPR) and Fourier Transform infrared spectroscopy (FTIR). In the SCR tests, MnOx–CeOy/γ-Al2O3–ZrO2 (MCAZ) showed outstanding NO removal efficiency and could abate the deactivation brought by SO2 and H2O. Moreover, the fluctuation of gas hourly space velocity (GHSV) appeared only a bit of influence on the activity at middle temperature. The characterization results exhibited that MnOx–CeOy/γ-Al2O3–ZrO2 owned bigger specific surface area and appropriate pore diameter, highly dispersed amorphous Mn2O3 as well as rational ratio of Ce4+/Ce3+. The H2-TPR results presented the promotion of the activity was partially due to the stronger oxidation ability at low temperature. Through the FTIR analysis, and combining with the mechanism proposed by earlier research, it was supposed that the highly reactive nitrates on the surface favored the high NO conversion. Besides, FTIR revealed that the bidentate sulfates formed by adsorbed SO2 produced new Lewis acid sites which promoted NH3 adsorption and reduced the poisoning effect of SO2 and H2O.

In this study, molasses was used as binder for the pelletization of hydrochar to enhance the fuel and storage properties. The basic fuel properties of the pellets including the proximate analysis and the higher heating value (HHV) were evaluated. The compressive strength was assessed and binding surface of the pellets was analyzed by SEM and ZIESS microscope, and the moisture uptake and combustion properties were analyzed by TG. The results suggested that, with molasses addition from 10% to 20%, the HHV of pellets was decreased while the mass density and energy density of the pellets significantly increased to a range of 947.1–1301.9 kg/m3 and 23.55–33.40 GJ/m3, respectively. The “sold bridge” formation from molasses by recrystallization of sugar enhanced the tensile strength of the pellets, with 260–20% exhibiting the highest value (6.44 MPa), while the maximum load distance of the molasses pellets decreased. In addition, the molasses binder also delayed the moisture uptake rate and slightly increased the EMC content which depended more on the HTC temperature. The combustion analysis showed that the molasses binder decreased the ignition temperature (17–42 °C), and the maximum mass lose rate decreased about 0.6–0.8%/°C, indicating that molasses pellets was combusted in a moderate process. The results suggested that molasses binder assisted pelletization of hydrochar from food waste had potentials for the preparation as solid biofuel.

In order to implement Hg 0 control strategy in a wet scrubber, oxidation of elemental mercury (Hg 0 ) in the simulated coal-fired flue gas by UV/Fenton system was investigated. Effects of different operation parameters have been studied, including initial solution pH, H 2 O 2 , TiO 2 and Fe 2+ concentration, solution temperature, gas flow rate and flue gas components (O 2 , SO 2 and NO). The main ion products in the solution have been analyzed. The experimental results suggested that oxidation of Hg 0 was inhibited with the increase of initial solution pH and gas flow rate. Additionally, with the increase of the H 2 O 2 , TiO 2 , Fe 2+ concentration and solution temperature, the Hg 0 oxidation efficiency was enhanced to the maximum at first and then decreased. Hg 0 oxidation can be significantly inhibited by SO 2 and NO when the flue gas was absence of O 2 , but the oxidation capacity was recovered with 9% O 2 exist in the flue gas. SO 2 showed an inhibition effect on Hg 0 oxidation, while the inhibition was weakened at higher SO 2 concentration. Different NO concentration had an insignificant effect on Hg 0 oxidation process under the experimental conditions. In the case of presence and absence of flue gas components (9% O 2 , 800 ppm SO 2 , 600 ppm NO) and under the optimal conditions (pH = 1, [H 2 O 2 ] = 0.05 mol/L; [TiO 2 ] = 0.6 g/L; [Fe 2+ ]/[H 2 O 2 ] = 1/2; T = 40 °C), the average oxidation efficiency of Hg 0 can reach to 94.4% and 98.5%, respectively.

Black carbon (BC) particles were removed from experimental flue gas by the surfactant solutions of sodium dodecylbenzene sulfonate (SDBS), hexadecyl trimethyl ammonium bromide (CTAB), fatty alcohol polyoxyethylene ether-9 (AEO-9) and polyoxy ethrlene nonyl phinyl ether-10 (TX-10), as well as AEO-9-SDBS, AEO-9-CTAB and SDBS-CTAB, in a new type of umbrella plate scrubber. Among the four independent surfactants, AEO-9 has the lowest surface tension, 35.9 mN/m, which resulted in the highest BC removal ratio among the alone surfactants. The experimental conditions were as follows: dust concentration = 3000 mg/m3; gas velocity = 14 m/s; liquid-gas ratio = 0.80 l/m3; and gas flow = 400 m3/h. When the mole ratio of the mixed surfactants was 1:1, the lowest surface tension could be detected among the studied mixed surfactants. According to the molecular interaction parameters (beta) and the mole ratio of surfactant 1 in the mixture (x1), the synergistic effects of AEO-9-SDBS and SDBS-CTAB solutions were obviously higher than those of AEO-9-TX-10 and AEO-9-CTAB. Therefore, AEO-9-SDBS solution had the lowest surface tension among the mixtures due to its beta0 and x1 = 0.85. The mixture solution of AEO-9-SDBS (1:1 mole ratio, 0.2 mmol/l) yielded the highest BC removal ratio, about 99.8%, and it was about 12% higher than that of only water, which was about 87.9%. The calculated critical micelle concentration was almost the same as that of the experimental concentration when the related equation was corrected by beta.

Total organic carbon (TOC) and humic acid (HA) are very strong contamination potential components in landfill leachate, which were treated by subcritical water catalytic oxidation technology with a batch reactor. Response surface methodology (RSM) was used to evaluate the effects of temperature (180–260 °C), peroxide coefficient (2–3), pH (4–8), and their interactive effects on TOC and HA removal efficiencies. The results demonstrated that RSM was an effective method for the optimization of experimental parameters in the treatment of landfill leachate. The results indicated that the effects on TOC removal efficiency were in the order temperature > pH > peroxide coefficient and that the order on HA removal efficiency was pH > temperature > peroxide coefficient. The experiments were performed in different heterogeneous (CuO, ZnO) and homogeneous (CuSO4·5H2O, FeSO4·7H2O, and Cu(NO3)2·3H2O) catalysts; the optimal parameters within the experimental range were temperature of 260 °C, pH of 4.0, peroxide coefficient of 3.0, and Cu(NO3)2·3H2O of 0.03 M. Under the optimum conditions, the TOC and HA removal efficiency can reach 86.42 and 66.10 %, respectively. Using gas chromatography coupled with mass spectrometry (GC-MS) to analyze the composition of liquid, 89 and 76 kinds of principal organic components were detected in the landfill leachate before and after treatment, respectively. In the raw landfill leachate, there were five kinds of organic matters, which belong to the US Environmental Protection Agency (USEPA) list of priority environmental pollutants. After the treatment, the toxic organics were not detected. In summary, the results suggested that the subcritical catalytic oxidation technology can be used as an effective method for the treatment of landfill leachate.

In this study, the effect of feed-water pH (pH = 2–12) on fate and risk of heavy metals (HMs) in hydrochars (HCs) was investigated. Hydrothermal carbonization (HTC) of sewage sludge (SS) was carried out with different feed-water pH at 270 °C. The research results showed that changing feed-water pH had a positive effect on accumulating Pb, Ni, Cd and Zn in HCs. Chemical forms of Cu and Cr converted from an unstable state to stable in the alkaline environment while in the acidic condition was opposite. The effect of feed-water pH on the chemical forms of HMs was variable but not significant. Risk assessments of I geo , E r i , RAC and RI were applied to evaluate the accumulation levels of individual metal, the potential ecological risks, the bio-availabilities and the comprehensive toxicity and sensitivity of HMs, respectively. The lowest pollution level of HMs was obtained at 270 °C with pH = 11.

0 removal from simulated flue gas. " The AICC samples possessed a joint oxidation effect on Hg 0 removal. " The Hg species adsorbed on AICC samples were identified mainly as HgO and HgCl2. " The roles of O2, NO, SO2 and H2O (g) in Hg 0 oxidation by AICC were explored. abstract Gas-phase elemental mercury (Hg 0 ) removal by activated coke impregnated with cerium chloride (AICC) was studied under simulated flue gas conditions. Brunauer-Emmett-Teller (BET), X-ray diffractogram (XRD), scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX) and X-ray photoelectron spectroscopy (XPS) analyses were used to characterize the samples. The effects of CeCl3 loading values, reaction temperatures and individual flue gas components including O2, NO, SO2 and H2O (g) on Hg 0 removal efficiency of AICC samples were investigated. Results showed that Hg 0

In this paper, catalytic samples of 10, 20, 30, 40 and 50% (w/w) urea/activated carbon fibre (AFC), 10% urea--5% La2O3/ACF, 10% urea--10% La2O3/ACF, 10% urea--15% La2O3/ACF, 20% urea--5% La2O3/ACF, 20% urea--10% La2O3/ACF, and 20% urea-15% La2O3/ACF were prepared and used for removal of NO under the condition of: NO, 500 ppm; O2, 21%; N2, balance, gas space velocity = 10000 m3 x h(-1) m(-3), total gas flow = 266.7 mL min(-1), temperature = 30 degreesC, relative humidity = 0%. The physical and chemical properties of the prepared catalysts were characterized by surface area measurements (BET) and scanning electron microscopy studies. Furthermore, the catalytic stability of 10% urea--5% La2O3/ACF under different concentrations of NO and O2 were also studied. The results showed that, among the prepared urea/ACF samples, 20% urea/ACF yielded the highest NO conversion at room temperature. Meanwhile, among the prepared urea--La2O3/ACF catalysts, 10% urea--5% La2O3/ACF yielded the highest NO conversion. Both 20% urea/ACF and 10% urea--5% La2O3/ACF could yield over 95% NO conversion at ambient temperature. However, 10% urea--5% La2O3/ACF had a more stable activity than that of 20% urea/ACF. The catalytic and characterization experimental results, including BET, thermogravimetric analysis and Fourier transform infrared analysis, showed that the NO selective catalytic reduction mechanism of urea-La2O3/ACF was different from that of ACF and urea/ACF. The NO was purified by ACF mainly by adsorption, whereas there was mainly a reduction reaction when NO was purified by urea/ACF or urea-La2O3/ACF. ACF-C was not only the catalyst but also the reducing agent for urea/ACF, whereas, for urea-La2O3/ACF, the catalytic centre was La2O3, and ACF was mainly the carrier. These differences resulted in the higher and more stable NO removal by 10% urea--5% La2O3/ACF.

Near-surface atmospheric dust in Changsha city of China was analyzed in terms of morphological and geochemical composition. Morphological and chemical composition of the dust particles were analyzed by environmental scanning electron microscopy coupled with an energy-dispersive X-ray analyzer. Results indicated that the atmospheric dusts were mainly composed of spherule, plate, irregularly shaped and agglomerate, which contains variable sizes and amounts of particles. The dust particles could be categorized into five groups based on their chemical characteristic: Al-, Si-, Ca-, C-rich particles and aggregate. These particles and aggregate could be directly related to nearby polluting activities, such as building construction, traffic emission and coal combustion. The X-ray diffraction results show that the main minerals for atmospheric dust are gypsum, quartz and calcite. Mica, halloysite, montmorillonite, hematite, brushite, zeolite, sepiolite, feldspar, alite, dickite, SiS2, Fe6(OH)2CO3, FeSO4, CdSO4, Pb(NO)2O3, Al2SO4(OH)4, As2O3SO3, (NH4)2SO4, NH4Cl, K(NH4)·Ca(SO4)2·H2O are also detected in samples. The identification of heavy metals shows that the concentrations of Cr (403.5 mg kg−1), Cu (126 mg kg−1), Zn (1541.5 mg kg−1), Cd (2.5 mg kg−1) and Pb (348 mg kg−1) in the atmospheric dust are much higher compared to background value of soil. It indicates that the heavy metal (Cr, Cu, Zn, Cd and Pb) in the atmospheric dust is mainly due to human activities. The identification of main sources of atmospheric dust collected in typical areas can help to control the polluting sources in urban area.

A cake collapse model was developed by taking the combined effects of fractal dimension, relaxation ratio, coordination number, and aggregate diameter into consideration. The cake porosity including intraaggregate and interaggregate porosities was modeled successively by three typical coordination numbers (n = 6, 8, and 12). Accordingly, an inversion method made it possible to deduce the coordination number using the measured cake porosities, and the reverse-calculated value with minimum error and the corresponding relaxation ratios were applied as the parameters for the model. As a result, the profiles of intraaggregate and interaggregate porosities and cake porosity were respectively predicted in contrast to the integrated variation of the relaxation ratio and the fractal dimension. Furthermore, a comparison between the model predictions of the cake pressure drop gradients with and without aggregate compression was conducted to validate the presence of cake collapse. The results show that the predictions based on the proposed collapse model are in agreement with the experiments, and the coordination number is one of the key factors that must be incorporated into the cake collapse models.

16 Polycyclic aromatic hydrocarbons (PAHs) in TSP were identified and quantified in samples collected during May and September of 2008, in Changsha, on three different sites: the city environmental protection agency of Changsha (A), the Middle School Attached to Hunan Normal University (B) and Yuhua district (C). The filters contained the particulate matter were extracted with dichloromethane in ultrasonic bath and then analyzed by gas chromatography/mass spectrometry (GC/MS). The total of 16 PAHs mean concentrations of summer at site A, B, C were 32.503 ng/m3 , 19.360 ng/m3 and 26.784 ng/m3, respectively; while the values for autumn at site A, B, C were 24.982 ng/m3, 17.088 ng/m3 and 15.465 ng/m3, respectively. The mean concentrations of PAHs of all samples in A site were 0.57 times higher than those measured at B site, and 0.38 times higher than at C site. The analysis of their distribution amongst the main emission sources was done through the diagnosis of concentration ratios of PAHs, as well as using statistical methods like principal component analysis. The diagnosis results of concentration ratios of PAHs suggested that the major polluting sources in the Changsha region during the studied period were the combustion of fuels, such as diesel oil, gasoline, wood and coal. The statistical analysis separated the 16 compounds studied into 3 and 4 factors for summer and autumn, separately. Factor 1 in summer represents vehicular emissions. Factor 2 represents emissions from the nature gas. Factor 3 represents emissions from combustion. In autumn, vehicle emissions, combustion sources, natural gas and coke oven were the major emissions.

Three sewage sludges with different diameters (1–0.5 mm, 0.5–0.2 mm and ≤0.2 mm) were pyrolyzed at laboratory scale, using a tube furnace under inert conditions to study the effects of temperature and diameter of sludge particles on the product yield distribution and composition. Upon comparing the yields of these sludges and analysis using GC-MS, it was found that a maximum of 32% oil yield was achieved at a pyrolysis temperature of 450°C and particle diameter of 0.5–0.2 mm, and the maximum oils evolution rate is observed between the temperatures of 400–500°C in all used sludges. These identified compounds in oils mainly consisted of aromatic rings linked by a branch chain and long straight hydrocarbon chains. The main compositions of the maximum ratio were C16H31N (Hexadecanenitrile) 12.49% in oil from 1–0.5 mm diameter particle, C16H32O3 (16-Hydroxyhexadecanoic acid) 7.53% from in oil 0.5–0.2 mm diameter particles, and C16H32O3 (16-Hydroxyhexadecanoic acid) 11.2% in oil from ≤0.2 mm diameter particles....

Polycyclic aromatic hydrocarbons (PAHs) were measured in airborne particulate matter (PM) collected by an eight-stage (S0, S1, …, S7, and SF) particle sizing sampler in three sampling periods, 85 h (85-h) each period. The measured particle-phase PAHs (P-only) data set and the sum of predicted gas-phase and measured particle phase PAHs (predicted G + P) data set considering the effect of gas/particle partitioning were used in positive matrix factorization (PMF) for source apportionment. Benzo[a]pyrene equivalent concentration (BaPeq) and incremental life cancer risk (ILCR) model were utilized for risk assessment of PAHs. The average concentrations of 85-h PM10 and PM2.1 were 292.729 and 142.642 μg/m3, respectively. The average concentration of 15 PAHs was 480.777 ng/m3 in PM10 and 254.464 ng/m3 in PM2.1. PAHs showed unimodal distribution among the nine sampling stages and S5 collected the most concentrations of PAHs and PM. PAHs with over four aromatic rings tended to accumulate in fine PM especially in S5 and S6 while PAHs with less than four rings preferred to stay in coarse PM especially in S0. A four source profiles for P-only were identified by PMF as follows with their source contributions: biomass burning (BB) (9.580 %), coal combustion (CC) (10.600 %), “air-surface exchange” (20.160 %), and vehicle emission (VE) (59.660 %). However, three source profiles for predicted G + P only identified including BB (93.330 %), CC (0.0600 %), and VE (6.610 %). The average 85-h average total BaPeq of 15 PAHs was 5.226 g/m3. S4, S5, and S6 had BaPeq concentrations greater than domestic standard concentration and ILCR value higher than 10−6.

In this study, attention was concentrated on the yields of bio-oil and toxicities of heavy metals (HMs) in liquefaction residues (LRs). Liquefaction of sewage sludge (SS) or oil-tea-cake (OTC) or mixtures of SS and OTC were carried out under the condition of supercritical methanol (SCM). Results showed that the addition of OTC extraordinarily increased the yields of oil from 37.9% (SS) to 86.2% (SS + OTC). Furthermore, with the liquefaction of SS and OTC mixture, the bioavailable fraction (F1 + F2) of Cd and Cu (F1 + F2) was decreased from 2.47 to 1.64 mg/kg and from 98.84 to 67.48 mg/kg, respectively. However, the bioavailable fraction of Zn (F1 + F2) increased from 122.03 to 204.69 mg/kg with the liquefaction of SS. The bioavailable fraction (F1 + F2) of Pb in LRs was 0%, which did not express any changes during the liquefaction process. Risk assessments of geo-accumulation index (I(geo)), risk assessment code (RAC) and modified potential ecological risk index (MRI) were applied to evaluate the bioavailabilities, the potential ecological risks and the pollution levels of HMs. The results show that the OTC in SS can decrease the risk of HMs in LRs. Cd attracted many concerns for the highest risk to the environment among all of the HMs. Here, the good results obtained means that SCM liquefaction of mixture of SS and OTC could be a preferable method for SS treatment.

Achievement of a higher NOx conversion ratio in selective catalytic reduction (SCR) at low temperature is challenging. In this work, pure activated carbon fibers (ACFs) were modified with different ratios of H2O (g), NaOH, CO2 and HNO3 respectively (named as modified ACF). The chemical and physical properties of modified ACFs were identified by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) methods. The NOx conversion ratio of ACF was improved from 56.1% to 82.4% at 80oC after modification with 30% (mass ratio) NaOH. These modified ACFs were further loading with the mixture of MnO2 and CeO2 in the form of metal salt solutions (named as Mn0.5Ce0.5O2/modified-ACF). The NOx conversion ratio of 30% SHACF remained similar at 80oC but was increased from 60.0% to 98.5% at 360oC after loading with Mn and Ce, which showed the best performance in SCR of NOx at low temperature. It could be seen that ACF delivered higher performance in low temperature SCR after being modified with these reactants above and further loading with metals. Based on chemical and physical characterization and the performance of the catalysts, the reasons for different performance of these catalysts in low temperature SCR are discussed.Supplementary_Material_Online.doc

The influence of temperature (550-850°C) on the characteristics of bio-oil and biochar from the pyrolysis of sewage sludge (SS) in a horizontal tube reactor was investigated. Results showed that when the pyrolysis temperature increased from 550°C to 850°C, the yield of bio-oil decreased from 26.16% (dry ash-free basis) to 20.78% (dry ash-free basis). Main components of bio-oil were phenols, esters, cholests, ketones, amides, indoles, and nitriles. Besides, the elevated heating rate of 25°C/min was demonstrated to favour the complete combustion of bio-oil. Moreover, caused by the increase in temperature, the yield of biochar decreased from 54.9 to 50.6 wt%, Brunauer-Emmet-Teller surface area increased from 48.51 to 81.28 m2/g. Furthermore, pH was increased from 5.93 of SS to 7.15-8.96 of biochar. The negative ζ-potential was also strengthened (-13.87 to -11.30 mV) and principal functional groups on the surface of biochar were -OH, C=O, C=C, -NO2, and S=O.

The influence of sewage sludge-based activated carbons (SSAC) on sewage sludge liquefaction has been carried out at 350 and 400 °C. SSAC increased the yield and energy density of bio-oil at 350 °C. The metallic compounds were the catalytic factor of SSAC obtained at 550 °C (SSAC-550), while carbon was the catalytic factor of SSAC obtained at 650 °C. Liquefaction with SSAC redistributed the species of heavy metals in solid residue (SR). With the addition of SSAC, the risk of Cu, Zn and Pb decreased at 350 °C, while at 400 °C the risk of Cd, Cu, and Zn were decreased. Ecological risk index indicated that 400 °C was preferable for the toxicity decrement of SR, while risk assessment code indicated that SR obtained at 350 °C contained lower risk. Considering the bio-oil yield, liquefaction at 350 °C with SSAC-550 was preferable.