The important role of EPS in mediated biosynthesis of CdS QDs: Comparative study of EPS-intact and EPS-free.

In this study, we investigated the adsorption of Cd(II) and the biosynthesis of CdS quantum dots (QDs) mediated by cells of sulfate-reducing bacteria before and after the removal of EPS to determine whether EPS or the cell wall plays a major role. Potentiometric titration revealed that the concentration of proton-active binding sites on cells with EPS (EPS-intact) was notably higher than that on cells without EPS (EPS-free) and that the sites were predominantly carboxyl, phosphoryl, hydroxyl, and amine groups. The protein content in EPS-intact cells was higher, and thus the Cd(II) adsorption capacity was stronger. The CdS QDs biosynthesized using EPS-intact possessed better properties, including uniform size distribution, good crystallinity, small particle size, high fluorescence, and strong antimicrobial activity, and the yields were significantly higher than those of EPS-free by a factor of about 1.5-3.7. Further studies revealed that alkaline amino acids in EPS play a major role and serve as templates in the biosynthesis of QDs, whereas they were rarely detected in the cell wall. This study emphasizes the important role of EPS in the bacterial binding of metals and efficient recycling of hazardous waste in water.

Microplastics as emerging contaminants in textile dyeing sludge: Their impacts on co-combustion/pyrolysis products, residual metals, and temperature dependency of emissions.

As emerging contaminants in textile dyeing sludge (TDS), the presence and types of microplastics (MPs) inevitably influence the combustion and pyrolysis of TDS. Their effects on the co-combustion/pyrolysis emissions and residual metals of TDS remain poorly understood. This study aimed to quantify the impacts of polyethylene (PE) and polypropylene (PP) on the transports and transformations of gaseous emissions and residual metals generated during the TDS combustion and pyrolysis in the air, oxy-fuel, and nitrogen atmospheres. Thermal degradation of the MPs in TDS occurred between 242-600 °C. MPs decomposed and interacted with the organic components of TDS to the extent that they increased the release of VOCs, dominated by oxygenated VOCs and hydrocarbons under the incineration and pyrolysis conditions, respectively. The presence of PE exerted a limited impact on the concentration and chemical form of metals, while PP reduced the residual amount of most metals due to the decomposition of mineral additives. Also, PP (with CaCO3 filler) reduced the acid-extractable content of cadmium, copper, and manganese in the bottom slag or coke but increased that of chromium. This study provides actionable insights into optimizing gas emissions, energy recovery, and ash reuse, thus reinforcing the pollution control strategies for both the MPs and TDS.

Actionable insights into hazard mitigation of typical 3D printing waste via pyrolysis.

3D printing waste (3DPW) contains hazardous substances, such as photosensitizers and pigments, and may cause environmental pollution when improperly disposed of. Pyrolysis treatment can reduce hazards and turn waste into useful resources. This study coupled thermogravimetric (TG), TG-Fourier transform infrared spectroscopy-gas chromatography/mass spectrometry, and rapid pyrolysis gas chromatography/mass spectrometry analysis to evaluate the pyrolytic reaction mechanisms, products, and possible decomposition pathways of the three typical 3DPW of photosensitive resin waste (PRW), polyamide waste (PAW), and polycaprolactone waste (PCLW). The main degradation stages of the typical 3DPW occurred at 320-580 °C. The most appropriate reaction mechanisms of PRW, PAW and PCLW were D1, A1.2 and A1.5, respectively. The main pyrolysis processes were the decomposition of the complex organic polymers of PRW, the breaking of the NH-CH2 bond and dehydration of -CO-NH- of PAW, and the breaking and reorganization of the molecular chains of PCLW, mainly resulting in toluene (C7H8), undecylenitrile (C11H21N), tetrahydrofuran (C4H8O), respectively. Unlike the slow pyrolysis, the rapid pyrolysis produced volatiles consisting mainly of phenol, 4,4'-(1-methylethylidene)bis- (C15H16O2) for PRW; 1,10-dicyanodecane (C12H20N2) for PAW; and ɛ-caprolactone (C6H10O2) for PCLW. These pyrolysis products hold great potential for applications. The findings of the study offer actionable insights into the hazard reduction and resource recovery of 3D printing waste.

Mediated biosynthesis of CdS QDs by EPS from Desulfovibrio desulfuricans sub sp. under carbon source-induced reinforcement.

This paper describes a unique molecular mechanism for the EPS-mediated synthesis of CdS QDs by sulfate-reducing bacteria (SRB) under carbon source-induced reinforcement. Under the induced by carbon sources (HCOONa, CH3COONa and C6H12O6), there was a significant increase in EPS production of SRB, particularly in protein, and the capacity of Cd(II) adsorption was further enhanced. CdS QDs were extracellularly synthesized by adding S2- after Cd(II) adsorption. The results showed that CdS QDs were wrapped or adhered by EPS, and the most significant increase in Arg and Lys among basic amino acids in EPS after HCOONa-induced was 133.34% and 63.89%, respectively. This may serve as a biological template for QD synthesis, producing protein gels with a large number of microcavities and controlling the nucleation of CdS QDs. The highest yield of HCOONa-CdS was achieved after induction, with 23.59 g/g biomass per unit strain, which was 447.34% higher than that before induction and was at a high level in previous studies. The synthesized CdS QDs were uniform in size distribution and had higher luminescence activity and a larger specific surface area than those synthesized by the chemical synthesis route, provides a new idea for EPS treatment of heavy metal wastewater and metal biorecovery.

Metagenomic next-generation sequencing for the diagnosis of oral and maxillofacial space infections.

Background/purpose: Metagenomic next-generation sequencing (mNGS) has been widely used for the detection of pathogens causing infectious diseases. This study aimed to evaluate the potential ability of mNGS to detect pathogens causing oral and maxillofacial space infection (OMSI) and compare the results with those of the traditional diagnostic microbial culture method. Materials and methods: We retrospectively reviewed the data of 218 patients diagnosed with OMSI who underwent microbial culture and mNGS at the Department of Oral Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, from July 2020 to January 2022. Results: The positivity rate of mNGS (216 cases) was significantly higher than that of microbial culture (123 cases). The most frequently detected bacteria were different between these two detection methods. Streptococcus constellatus (16.05%, 35), Streptococcus anginosus (15.69%, 34) and Klebsiella pneumoniae (6.88%, 15) were the most commonly isolated bacteria by culture. However, Peptostreptococcus stomatis (61.47%, 134), Parvimonas micra (68.35%, 149) and Streptococcus constellatus (57.34%, 125) were the most commonly detected bacteria by mNGS. mNGS also has advantages in diagnosing viral infections. The optimal numbers of diagnostic reads were 1162 and 588 for the diagnosis of Streptococcus anginosus and Streptococcus constellatus infections, respectively. Read numbers were significantly correlated with C-reactive protein (CRP), procalcitonin (PCT), and blood glucose levels and neutrophil percentage (NEUT%). Conclusion: For pathogens causing OMSI, mNGS had a higher rate of microbial pathogen detection and remarkable advantages in identifying coinfections involving viruses and fungi. The read numbers for mNGS are important for diagnostic accuracy and disease severity evaluation.

The predictive value of laboratory tests in oro-maxillofacial infection of different severity.

OBJECTIVE: We aimed to investigate the value of individual laboratory tests and combinations of tests for predicting disease severity. METHODS: We retrospectively reviewed 62 patients with space infections in the oral and maxillofacial head and neck regions. Patients were divided into three groups according to severity. Laboratory tests associated with disease severity were identified. RESULTS: As the severity of infection increased, leukocytes, neutrophils, C-reactive protein (CRP), procalcitonin (PCT), soluble interleukin receptor (sILR) 2, IL6, and creatinine (CR) increased. In the ROC analysis of group 1 (moderate infection) versus group 2 (severe infection), the area under the curve (AUC) values for leukocytes (AUC = 0.724), neutrophils (AUC = 0.714), PCT (AUC = 0.762) and a combination of the 3 tests (AUC = 0.768) suggested a strong predictive value. Furthermore, in the ROC analysis of group 2 (severe infection) versus group 3 (extremely severe infection), the AUC values for CRP (AUC = 0.84), PCT (AUC = 0.799), sIL2R (AUC = 0.937), IL6 (AUC = 0.863) and a combination of the four tests (AUC = 0.943) suggested a strong predictive value. CONCLUSIONS: Leukocytes, neutrophils, and PCT were associated with multispace infection and high severity. CRP, PCT, sIL2R, and/or IL6 were associated with extremely severe infections occurring in the oral and maxillofacial head and neck regions.

Radical-/non-radical-mediated catalyst activation of peroxymonosulfate for efficient atrazine degradation.

Efficient degradation technologies are urgent to be developed to avoid the ecological and healthy hazards brought from atrazine (ATZ). LaCoO3-δ/peroxymonosulfate (PMS) system was proved to have strong degradation capabilities to contaminants. In this work, we intended to investigate the effect of the synthesis method on LaCoO3-δ. However, the hydrothermal method yielded a new material (H-Co) with better catalytic performance than LaCoO3-δ, which showed stable catalytic ability at pH 3.0-9.0 and 5 consecutive cycles. The coexistence of inorganic Cl-, SO42-, NO3-, H2PO4-, HCO3- and organic humic acids exerted little influences on the H-Co/PMS system. In addition, the actual livestock and poultry breeding wastewater could be well degraded and mineralized by the H-Co/PMS system. Free radical burst experiments and EPR characterization were performed to verify the synergistic effects of free radicals and non-free radicals during ATZ degradation. Based on SEM, XRD, O2-TPD, FTIR, XPS, and electrochemistry characterizations, the efficient catalytic ability of H-Co could be attributed to the abundant oxygen vacancies, surface hydroxyl groups, zero-valent cobalt sites and high electronic conductivity. The degradation pathways were proposed based on the detection of degradation intermediates of ATZ by UPLC-MS. Moreover, the toxic of ATZ during the oxidation was evaluated by TEXT and E. coli inhibition assay. This work comprehensively analyzed the catalytic reaction mechanism of the H-Co/PMS system and provided a feasible pathway for the treatment of the actual livestock and poultry breeding wastewater.

Characteristics of EPS from Pseudomonas aeruginosa and Alcaligenes faecalis under Cd(II) stress: changes in chemical components and adsorption performance.

EPS (extracellular polymeric substance) production is a self-protection mechanism by which microorganisms slow or eliminate adverse effects in unfavorable environments. In this study, Pseudomonas aeruginosa and Alcaligenes faecalis were selected to explore changes in EPS components, especially protein components, under stress caused by different concentrations of Cd(II). The results showed that the protein content in EPS was the highest. The two strains achieved maximum EPS production levels of 109.17 and 214.96 mg/g VSS at Cd(II) stress concentrations of 20 and 50 mg/L, which were increased by 52.07% and 409.69% compared with the levels exhibited before stress, respectively. The protein content correlated very well with data from adsorption experiments. Furthermore, FTIR, 3D-EEM, and XPS results illustrated that after Cd(II) stress, C-N, C=O/-COOH, and R-NO2- moieties were formed in substantial quantities, and the stress effects of Pseudomonas aeruginosa were significantly higher than those of Alcaligenes faecalis. The results of this study showed that addition of Cd(NO3)2 effectively regulated the components of EPS, especially the protein content, and improved the adsorption capacity, which has application prospects for prevention and control of heavy metals.

Efficacy of needle aspiration in patients with oral-maxillofacial abscesses: A retrospective study of 15 consecutive patients.

The aim of this study was to determine the adequacy and safety of needle aspiration (NA) as an alternative to open surgical drainage for oral-maxillofacial abscesses. Fifteen consecutive patients who were diagnosed with oral-maxillofacial abscesses via contrast-enhanced CT from January 2020 to December 2020 were included. All patients were on antibiotics and treated with NA under local anaesthesia using a 20 mL syringe. Data collection included patient characteristics, signs and symptoms, physical examinations, laboratory tests, imaging findings, and outcomes. Next-generation sequencing (NGS) was used to identify the infectious microorganisms from the abscess samples. The study included 15 patients with oral-maxillofacial abscesses. None of our 15 patients required surgical incision and drainage, although repeat aspiration was required. However, after the first NA, the pain was reportedly extremely relieved for all patients. The average duration of antibiotic treatment was 9.20 ± 5.15 days (range 4-23 days). The abscess-affected spaces mainly included the masseter space and submandibular space. Odontogenic infection was the most common aetiology in 15 patients (10/15). The average volume of the abscesses on CT was 5866.26 ± 3627.18 mm3. The main pathogens identified in this study were Prevotella oris (5/15), Peptostreptococcus stomatis (4/15) and Porphyromonas endodontalis (2/15). According to the results of our study, the data support the use of NA as an effective, minimally invasive treatment modality for oral-maxillofacial abscesses. Surgeons should familiarise themselves with this technique, as it can easily be performed in the clinic using local anaesthesia, culture samples may be obtained, and airway obstruction and pain may be relieved.

Effects of different exogenous cadmium compounds on the chemical composition and adsorption properties of two gram-negative bacterial EPS.

Three different Cd(II) compounds were used to regulate Pseudomonas aeruginosa and Alcaligenes faecalis EPS (extracellular polymeric substances). The purpose of this study was to improve the content of EPS protein and the adsorption capacity of Cd(II) by different Cd(II) compounds. The results showed that Cd(NO3)2 had the best stress/induction effect on the two strains. Under the best stress/induction, the protein in EPS of the two strains increased most obviously, and the adsorption capacity of Cd(II) was increased by more than 40%. Under these conditions, the kinetics of the adsorption process of Cd(II) by Cd(NO3)2-EPSA. F (EPS produced by Alcaligenes faecalis under Cd(NO3)2 stress) could be well fitted by the Langmuir isotherm model, and the theoretical maximum adsorption amount of 1111.11 mg/g EPS could be obtained. The results of 3D-EEM, FTIR and XPS indicated that proteins, especially CO, CN and NH in proteins, played a major role in the removal of Cd(II) by Cd(NO3)2-EPSA. F. The results of this study show that the addition of Cd(NO3)2 can effectively regulate the content of chemical components, especially the content of protein, and thus greatly improve the removal efficiency of heavy metals, which shows great application prospects in the prevention and control of heavy metal pollution.

Enhancement and analysis of Anthracene degradation by Tween 80 in LMS-HOBt.

This study examines the specific effect of Tween 80 on the conversion of anthracene (ANT) in laccase medium system regarding surfactant chemical changes and mechanism. The conversion rate and degradation products of ANT were investigated in different concentrations of Tween 80 solution. Between Tween 80 concentration 0-40 critical micelle concentrations (CMC), the kinetic parameter-k (h-1) and corresponding half-life T1/2 decreased with increasing concentration. When Tween 80 was above 20 CMC the laccase-medium system converted > 95% of ANT to anthraquinone within 12 h. During the entire enzymatic reaction, the laccase activity in the system increased with increasing Tween 80 concentration. Combined with GC/MS analysis of the product, it was speculated that hydrogens belonging to the ether-oxygen bond and carbon-carbon double bond α-CH of Tween 80, were removed by the laccase-media system, promoting its degradation. Additionally, enhanced activity caused by oxygen free radicals (ROS) such as RO• and ROO•, continuously oxidized Tween 80, which in turn produced free radicals while converting ANT. This study provides new theoretical support toward the application of surfactants in the elimination of polycyclic aromatic hydrocarbons.

Electrochemical and microbial community responses of electrochemically active biofilms to copper ions in bioelectrochemical systems.

Heavy metals play an important role in the conductivity of solution, power generation and activity of microorganisms in bioelectrochemical systems (BESs). However, effect of heavy metal on the process of exoelectrogenesis metabolism and extracellular electron transfer of electrochemically active biofilms (EABs) was poorly understood. Herein, we investigated the impact of Cu2+ at gradually increasing concentration on the morphological and electrochemical performance and bacterial communities of anodic biofilms in mixed-culture BESs. The voltage output decreased continuously and dropped to zero at 10 mg L-1, which was attributed to the toxic inhibition that cased anodic biofilm damage and decreased secretion of outer membrane cytochromes. When stopping the introduction of Cu2+ to anodic chamber, the maximum voltage production recovered 75.1% of the voltage produced from BES and coulombic efficiency was higher but acetate removal rate was lower than that before Cu2+ addition, demonstrating the recovery capability of EABs was higher compared to nonelectroactive bacteria. Moreover, SEM-EDS and XPS suggested that most of Cu2+ was adsorbed by the anode electrode and reduced by EABs on anode. Compared to the open-circuit BES, the flow of electrons through a circuit could improve the reduction of copper. Community analysis showed a decrease in Geobacter accompanied by an increase in Stenotrophomonas in response to Cu2+ shock in anodic chamber.

Enhanced bioelectricity generation and azo dye treatment in a reversible photo-bioelectrochemical cell by using novel anthraquinone-2,6-disulfonate (AQDS)/MnOx-doped polypyrrole film electrodes.

A novel anthraquinone-2,6-disulfonate/MnOx-doped polypyrrole film (AQDS/Mn/PPy) electrode was prepared by one-step electropolymerization method and was used to improve performance of a reversible photo-bioelectrochemical cell (RPBEC). The RPBEC was operated in polarity reversion depended on dark/light reaction of alga Chlorella vulgaris by which sequential decolorization of azo dye and mineralization of decolorization products coupled with bioelectricity generation can be achieved. The results showed that formation of uniform AQDS/Mn/PPy film significantly enhanced electroactive surface area and electrocatalytic activity of carbon electrode. The RPBEC with AQDS/Mn/PPy electrodes demonstrated 77% increases in maximum power and 73% increases in Congo red decolorization rate before polarity reversion, and 198% increases in maximum power and 138% increases in decolorization products mineralization rate after polarity reversion, respectively, compared to the RPBEC with bare electrode. This was resulted from simultaneous dynamics improvement in half-reaction rate of anode and photo-biocathode due to enhanced electron transfer and algal-bacterial biofilm formation.

Spent mushroom substrate biochar as a potential amendment in pig manure and rice straw composting processes.

Spent mushroom substrate (SMS) is a bulky waste byproduct of commercial mushroom production, which can cause serious environmental problems and, therefore, poses a significant barrier to future expansion of the mushroom industry. In the present study, we explored the use of SMS as a biochar to improve the quality of bio-fertilizer. Specifically, we performed a series of experiments using composting reactors to investigate the effects of SMS biochar on the physio-chemical properties of bio-fertilizer. Biochar was derived from dry SMS pyrolysed at 500°C and mixed with pig manure and rice straw. Results from this study demonstrate that the addition of biochar significantly reduced electrical conductivity and loss of organic matter in compost material. Nutrient analysis revealed that the SMS-derived biochar is rich in fertilizer nutrients such as P, K, Na, and N. All of these findings suggest that SMS biochar could be an excellent medium for compost.

Analysis of the Metabolites of Indole Degraded by an Isolated Acinetobacter pittii L1.

Indole and its derivatives are typical nitrogen heterocyclic compounds and have been of immense concern since they are known for the risk of their toxic, recalcitrant, and carcinogenic properties for human and ecological environment. In this study, a Gram-negative bacterial strain of eliminating indole was isolated from a coking wastewater. The strain was confirmed as Acinetobacter pittii L1 based on the physiological and biochemical characterization and 16S ribosomal DNA (rDNA) gene sequence homology. 400 mg/L indole could be completely removed within 48 h by the strain on the optimum condition of 37°C, pH 7.4, and 150 rpm. The organic nitrogen was converted to NH3-N and then to NO3- and the organic carbon was partially transferred to CO2 during the indole biodegradation. The metabolic pathways were proposed to explain the indole degradation based on the liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis of indigo, 4-(3-Hydroxy-1H-pyrrol-2-yl)-2-oxo-but-3-enoic acid, and isatin. The toxicity of the biodegradation products was evaluated using the Microtox test, which revealed that the metabolites were more toxic than indole. Our research holds promise for the potential application of Acinetobacter pittii L1 for NHCs degradation, production of indigoids, and soil remediation as well as treatment of indole containing wastewater.

Effect of K2FeO4/US treatment on textile dyeing sludge disintegration and dewaterability.

The effect of potassium ferrate/ultrasonic (K2FeO4/US) treatment on the physicochemical features of textile dyeing sludge was studied. The soluble chemical oxygen demand (SCOD), deoxyribonucleic acid (DNA), sludge volume index (SVI), sludge viscosity, capillary suction time (CST) and particle size were measured to understand the observed changes in the sludge physicochemical features. The results showed that the combined K2FeO4/US treatment presented great advantages for disrupting the sludge floc structure over K2FeO4 or ultrasonic treatments alone. The optimal parameters of sludge disintegration were found to be a K2FeO4 treatment time of 60 min, a K2FeO4 dosage of 0.5936 g/g SS, an ultrasonic time of 15 min and an ultrasonic intensity of 0.72 W/mL. The initial median diameter of the sludge particles was 15.24 µm, and this value decreased by 35.89%. The CST was initially 59.6 s and increased by 231%, whereas the SVI was 97.78 mL/g and decreased by 25.89%. Scanning electron microscope (SEM) images indicated that the sludge surface was irregular and loose with a large amount of channels or voids during K2FeO4/US treatment. K2FeO4/US treatment synergistically enhanced the sludge solubilization and reached 668.67 mg/L SCOD, which is 31.81% greater than the additive value obtained with K2FeO4 treatment alone (215.95 mg/L) or with ultrasonic treatment alone (240 mg/L).

Enhanced dewaterability of textile dyeing sludge using micro-electrolysis pretreatment.

The effects of micro-electrolysis treatment on textile dyeing sludge dewatering and its mechanisms were investigated in this study. Capillary suction time (CST) and settling velocity (SV) were used to evaluate sludge dewaterability. Extracellular polymeric substances (EPS) concentration and sludge disintegration degree (DDSCOD) were determined to explain the observed changes in sludge dewaterability. The results demonstrated that the micro-electrolysis could significantly improve sludge dewaterability by disrupting the sludge floc structure. The optimal conditions of sludge dewatering were the reaction time of 20 min, initial pH of 2.5, Fe/C mass ratio of 1/1, and the iron powder dosage of 2.50 g/L, which achieved good CST (from 34.1 to 27.8 s) and SV (from 75 to 60%) reduction efficiency. In addition, the scanning electron microscope (SEM) images revealed that the treated sludge floc clusters are broken up and that the dispersion degree is better than that of a raw sludge sample. The optimal EPS concentration and DDSCOD to obtain maximum sludge dewaterability was 43-46 mg/L and 4.2-4.9%, respectively. The destruction of EPS was one of the primary reasons for the improvement of sludge dewaterability during micro-electrolysis treatment.

Aromatic amine contents, component distributions and risk assessment in sludge from 10 textile-dyeing plants.

Aromatic amines (AAs), which are components of synthetic dyes, are recalcitrant to the wastewater treatment process and can accumulate in sludge produced by textile-dyeing, which may pose a threat to the environment. A comprehensive investigation of 10 textile-dyeing plants was undertaken in Guangdong Province in China. The contents and component distributions of AAs were evaluated in this study, and a risk assessment was performed. The total concentrations of 14 AAs (Σ14 AAs) varied from 11 µg g(-1)dw to 82.5 µg g(-1)dw, with a mean value of 25 µg g(-1)dw. The component distributions of AAs were characterized by monocyclic anilines, of which 2-methoxy-5-methylaniline and 5-nitro-o-toluidine were the most dominant components. The risk quotient (RQ) value was used to numerically evaluate the ecological risk of 14 AAs in the environment. The result showed that the 14 AAs contents in textile-dyeing sludge may pose a high risk to the soil ecosystem after being discarded on soil or in a landfill.

Fate of volatile aromatic hydrocarbons in the wastewater from six textile dyeing wastewater treatment plants.

The occurrence and removal of benzene, toluene, ethylbenzene, xylenes, styrene and isopropylbenzene (BTEXSI) from 6 textile dyeing wastewater treatment plants (TDWTPs) were investigated in this study. The practical capacities of the 6 representative plants, which used the activated sludge process, ranged from 1200 to 26000 m(3) d(-1). The results indicated that BTEXSI were ubiquitous in the raw textile dyeing wastewater, except for isopropylbenzene, and that toluene and xylenes were predominant in raw wastewaters (RWs). TDWTP-E was selected to study the residual BTEXSI at different stages. The total BTEXSI reduction on the aerobic process of TDWTP-E accounted for 82.2% of the entire process. The total BTEXSI concentrations from the final effluents (FEs) were observed to be below 1 µg L(-1), except for TDWTP-F (2.12 µg L(-1)). Volatilization and biodegradation rather than sludge sorption contributed significantly to BTEXSI removal in the treatment system. BTEXSI were not found to be the main contaminants in textile dyeing wastewater.

Effect of different sulfides on cadmium distribution during sludge combustion based on experimental and thermodynamic calculation approaches.

The effects of sulfur compounds on the migration of a semi-volatile heavy metal (cadmium) during sludge incineration were investigated with two methods, i.e., experiments in a tubular furnace reactor and thermodynamic equilibrium calculations. The representative typical sludge with and without the addition of sulfur compounds was incinerated at 850 °C. The partitioning of Cd among the solid phase (bottom ash) and gas phase (fly ash and flue gas) was quantified. The results indicate that sulfur compounds in the elemental form and a reduced state could stabilize Cd in the form of CdS, aluminosilicate minerals, and polymetallic sulfides, whereas sulfur in the oxidized forms slightly increases Cd volatilization during incineration. For Cd solidification points, the inhibition effect on the volatilization of Cd is as follows: S > Na2SO4 > Na2S. Chemical equilibrium calculations indicate that sulfur binds with Cd and alters Cd speciation at low temperatures (<950 K). Furthermore, SiO2- and Al2O3-containing minerals can function as sorbents stabilizing Cd as condensed phase solids (CdSiO4 and CdAl2O4) according to the results of equilibrium calculations. These findings provide useful information for understanding the partitioning of Cd and thus facilitate the development of strategies to control Cd volatilization during sludge incineration.