Sludge,the massive by-product of the sewage system,became a major challenge for the wastewater treatment industry.Yet,conventional methods often face challenges like low efficiency,high energy consumption,and environm...Sludge,the massive by-product of the sewage system,became a major challenge for the wastewater treatment industry.Yet,conventional methods often face challenges like low efficiency,high energy consumption,and environmental pollution.Especially,the improper treatment and disposal of toxic sludge generated from different industrial processes or specific wastewater treatment operations exerted significant pressure and threat to hydrosphere,pedosphere,atmosphere and even biosphere.展开更多
The organic compound composition ofwastewater,serves as a crucial indicator for the operational performance of activated sludge processes and has a major influence on the development of filamentous bulking in activate...The organic compound composition ofwastewater,serves as a crucial indicator for the operational performance of activated sludge processes and has a major influence on the development of filamentous bulking in activated sludge.This study focused on the impact of typical soluble and slowly-biodegradable organic compounds,investigating the pathways through which these substrates affect the occurrence of filamentous bulking in systems operated under both high-and low-oxygen conditions.Results showed that slowly-biodegradable organic compounds lead to a concentrated distribution of microorganisms within flocs,with inward growth of filamentous bacteria.Both Tween-80 and granular starch treated systems exhibited a significant increase in protein content.The glucose system,utilizing soluble substrates,exhibited a markedly higher total polysaccharide content.Microbial communities in the Tween-80 and granular starch treated systems were characterized by a higher abundance of bacteria known to enhance sludge flocculation and settling,such as Competibacter,Xanthomonadaceae and Zoogloea.These findings are of high significance for controlling the operational performance and stability of activated sludge systems,deepening our understanding and providing a novel perspective for the improvement of wastewater treatment processes.展开更多
Drying operations are of grave importance to realize the reduction and utilization of sewage sludge resources,but the conventional thermal evaporation drying(TED)technology presents challenges due to the need for a la...Drying operations are of grave importance to realize the reduction and utilization of sewage sludge resources,but the conventional thermal evaporation drying(TED)technology presents challenges due to the need for a large amount of thermal energy to conquer the phase-change latent heat of moisture.Herein,we report a non-phase change technology based on particle high-speed self-rotation in a cyclone for fast,low-temperature drying of viscous sludge with high-moisture contents.Dispersed phase medium(DPM)is introduced into the cyclone self-rotation drying(CSRD)reactor to enhance the dispersion of the viscous sludge.The effects of carrier gas temperature,feeding rate,size,and proportion of DPM particles in the drying process are systematically examined.Under optimal operating conditions,the weighted content of moisture in the viscous sludge could be reduced from 80%to 15.01%in less than 5 s,achieving a high drying efficiency of 95.79%.Theoretical calculations also reveal that 89.26%of the moisture is removed through non-phase change pathway,contributing to a 522-fold increase in the drying rate of CSRD compared to TED technology.This investigation presents a sustainable effective approach for high moisture viscous sludge treatment with low energy consumption and carbon emissions.展开更多
We examined the enhancing effects of different dosages of product of Centrifugation of Bacterial Liquid(product of CBL)on the performance of slag-fGD gypsum-cement-bentonite-sludge system using MICP technology.We anal...We examined the enhancing effects of different dosages of product of Centrifugation of Bacterial Liquid(product of CBL)on the performance of slag-fGD gypsum-cement-bentonite-sludge system using MICP technology.We analyzed the multifaceted performance of the solidified sludge from macroscopic and microscopic perspectives.The experimental results reveal that the increase in product of CBL dosage results in positive impacts on the solidified sludge,including higher side compressive strength,lower leachate heavy metal concentration,and improved crack repair rates.At a 0.4%product of CBL doping concentration,the strength of the solidified sludge is enhanced by 26.6%at 3 d,61.2%at 7 d,and 13.9%at 28 d when compared to the unmodified solidified sludge.After 28 days,the concentrations of Zn and Cu ions reduce by 58%and 18%,respectively,and the crack repair rate is 58.4%.These results demonstrate that the increase in heavy metal concentration in the leachate leads to an increase in the strength of the solidified sludge.The strengthening procedure heavily relies on the mineralisation reaction of Bacillus pasteurii,which produces a substantial amount of CaCO_(3)to cement the particles and fill the pores initially.The modified solidifying sludge exhibits a self-repairing effect and an enhanced multifaceted performance as a result of oxygen being restored after crack formation and reactivation of Bacillus pasteurii.Such conditions facilitate the body's recovery.展开更多
This study investigates the innovative reuse of sewage sludge with eco-friendly alkaline solutes to improve clayey soil without conventional cementitious binders.The unconfined compressive strength(UCS)was the main cr...This study investigates the innovative reuse of sewage sludge with eco-friendly alkaline solutes to improve clayey soil without conventional cementitious binders.The unconfined compressive strength(UCS)was the main criterion to assess the quality and effectiveness of the proposed solutions,as this test was performed to measure the strength of the stabilized clay by varying binders’dosages and curing times.Moreover,the direct shear test(DST)was used to investigate the Mohr-Coulomb parameters of the treated soil.Microstructure observations of the natural and treated soil were conducted using scanning electron microscope(SEM),energy-dispersive spectroscopy(EDS),and FTIR.Furthermore,toxicity characteristic leaching procedure(TCLP)tests were performed on the treated soil to investigate the leachability of metals.According to the results,using 2.5%of sewage sludge activated by NaOH and Na_(2)SiO_(3)increases the UCS values from 176 kPa to 1.46 MPa after 7 d and 56 d of curing,respectively.The results of the DST indicate that sewage sludge as a precursor increases cohesion and enhances frictional resistance,thereby improving the Mohr-Coulomb parameters of the stabilized soil.The SEM micrographs show that alkali-activated sewage sludge increases the integrity and reduces the cavity volumes in the stabilized soil.Moreover,TCLP tests revealed that the solubility of metals in the treated soil alkaliactivated by sewage sludge significantly decreased.This study suggests that using sewage sludge can replace cement and lime in ground improvement,improve the circular economy,and reduce the carbon footprint of construction projects.展开更多
In this study,the effects of different salinity gradients and addition of compatible solutes on anaerobic treated effluent water qualities,sludge characteristics and microbial communities were investigated.The increas...In this study,the effects of different salinity gradients and addition of compatible solutes on anaerobic treated effluent water qualities,sludge characteristics and microbial communities were investigated.The increase in salinity resulted in a decrease in particle size of the granular sludge,which was concentrated in the range of 0.5-1.0 mm.The content of EPS(extracellular polymeric substances)in the granular sludge gradually increased with increasing salinity and the addition of betaine(a typical compatible solute).Meanwhile,the microbial community structure was significantly affected by salinity,with high salinity reducing the diversity of bacteria.At higher salinity,Patescibacteria and Proteobacteria gradually became the dominant phylum,with relative abundance increasing to 13.53%and 12.16%at 20 g/L salinity.Desulfobacterota and its subordinate Desulfovibrio,which secrete EPS in large quantities,dominated significantly after betaine addition.Their relative abundance reached 13.65%and 7.86%at phylum level and genus level.The effect of these changes on the treated effluent was shown as the average chemical oxygen demand(COD)removal rate decreased from 82.10%to 79.71%,78.01%,68.51%and 64.55%when the salinity gradually increased from 2 g/L to 6,10,16 and 20 g/L.At the salinity of 20 g/L,average COD removal increased to 71.65%by the addition of 2 mmol/L betaine.The gradient elevated salinity and the exogenous addition of betaine played an important role in achieving stability of the anaerobic system in a highly saline environment,which provided a feasible strategy for anaerobic treatment of organic saline wastewater.展开更多
The development of sustainable sludge management systems requires looking at them with a new vision in which the concepts of SD(Sustainable Development)must integrate those of CE(Circular Economy),both concepts subjec...The development of sustainable sludge management systems requires looking at them with a new vision in which the concepts of SD(Sustainable Development)must integrate those of CE(Circular Economy),both concepts subject to the principles of TD(Thermodynamics),thus allowing the adoption of actions that are all the more effective the more complete the evaluation of the social dimension has been.This involves a new“Way of thinking”which sees the sludge system as the“Locomotive”of the entire wastewater/sludge treatment train and is developed through“Ways of acting”which includes both“Technical”actions to maximize recoveries of useful materials and/or or energy,and“Socio/Institutional”actions to overcome barriers linked to local cultures and traditions,also considering that the specific local context heavily influences the choices capable of satisfying the concepts of CE.It follows the need of issuing realistic and applicable regulations and overcoming social barriers,such as lack of infrastructure and/or qualified personnel,to achieve an effective integration of the concepts of CE with the more general ones of sustainability.展开更多
Catalytic oxidation of NO at room temperature was carried out over nitrogen(N)-doped sludge char(SC)prepared from pyrolysis ofmunicipal sewage sludge,and urea was adopted as nitrogen source.The effects of different N-...Catalytic oxidation of NO at room temperature was carried out over nitrogen(N)-doped sludge char(SC)prepared from pyrolysis ofmunicipal sewage sludge,and urea was adopted as nitrogen source.The effects of different N-doping methods(one-step and two-step method),dried sludge(DS)/urea mass ratios(5:1,4:1,3:1,2:1,and 1:1),SC preparation procedures(pyrolysis only,pyrolysis with acid washing,and pyrolysis with KOH activation and acid washing),and different pyrolysis temperatures(500,600,700,and 800°C)on the catalytic oxidation of NO were compared to optimize the procedure for SC preparation.The results indicated that N-doping could obviously promote the catalytic performance of SC.The one-step method with simultaneous sludge pyrolysis(at 700°C),KOH activation,and N-doping(DS/urea of 3:1)was the optimal procedure for preparing the N-doped SC with the NO conversion rate of 54.7%,whereas the optimal NO conversion rate of SC without N-doping was only 47.3%.Urea worked both as carbon and nitrogen source,which could increase about 2.9%-16.5%of carbon and 24.8%-42.7%of nitrogen content in SC pyrolyzed at 700°C.N-doping significantly promoted microporosity of SC.The optimal N-doped SC showed specific surface areas of 571.38 m^(2)/g,much higher than 374.34 m^(2)/g of the optimal SC without N-doping.In addition,N-doping also increased amorphousness and surface basicity of SC through the formation of N-containing groups.Finally,three reaction paths,i.e.microporous reactor,active sites,and basic site control path,were proposed to explain the mechanism of N-doping on promoting the catalytic performance of NO.展开更多
Recovery of rare earth elements(REEs)from bulk Nd-Fe-B scrap by chlorination with NH_(4)Cl as a chlorinating agent has been reported to be an energy efficient and environmentally friendly method.However,the reaction m...Recovery of rare earth elements(REEs)from bulk Nd-Fe-B scrap by chlorination with NH_(4)Cl as a chlorinating agent has been reported to be an energy efficient and environmentally friendly method.However,the reaction mechanism and phase evolution of the low-temperature selective chlorination process of Nd-Fe-B sludge are not clear.In this paper,we systematically investigated the lowtemperature selective chlorination process of Nd-Fe-B sludge with NH4Cl by combining thermokinetic theoretical calculations and experiments,and revealed its reaction mechanism.The phase evolution during chlorination was determined by X-ray diffraction(XRD),scanning electron microscopy(SEM)and ene rgy-dispersive X-ray spectroscopy(EDS)characterization as well as co mputational analysis of the phase stability diagram of the M-O-Cl system.To determine the optimum chlorination conditions,the effects of chlorinating agent dosage,reaction temperature and reaction time on the reaction were investigated.The results show that the rare earth components in Nd-Fe-B sludge are selectively chlorinated to RECl3and the formation of REOCl is avoided in the temperature range of 300-420℃,while the iron components are preferentially oxidized to Fe2O3.The selective chlorination reaction is consistent with the unreacted shrinking core model,and the rate-controlling step of the reaction is the internal diffusion process of NH4Cl through the transition layer of the reactant product to the surface of the Nd-Fe-B sludge.The complete chlorination of REEs is successfully achieved and 99.8%of REEs are selectively extracted into the leaching solution under optimal chlorination conditions(300℃,2.5 times of stoichiometric amount,4 h).展开更多
Anaerobic ammonia oxidation(Anammox)is an economical and sustainablewastewater nitrogen removal technology,and its application in the mainstream process is the inevitable trend of the development of Anammox.However,ho...Anaerobic ammonia oxidation(Anammox)is an economical and sustainablewastewater nitrogen removal technology,and its application in the mainstream process is the inevitable trend of the development of Anammox.However,how to effectively enriching Anammox bacteria from the activated sludge remains challenging and restricts its extensive applications.In this study,the rapid and efficient enrichment of Anammox bacteriawas achieved by raising the reflux ratio and nitrogen loading rate(NLR)using conventional activated sludge as the inoculant.In the screening phase(days 1–90),the reflux ratio was increased to discharge partial floc sludge,resulting in the relative abundance of Candidatus Brocadiaceae increased from0.04%to 22.54%,which effectively reduced thematrix and spatial competition between other microorganisms and Anammox bacteria.On day 90,the stoichiometric ratio of the Anammox process closely approached the theoretical value of 1:1.32:0.26,indicating that the Anammox reaction was the primary nitrogen removal process in the system.In the enrichment phase(days 91–238),the NLR increased from 0.43 to 1.20 kgN/(m^(3)·d)and removal efficiency was 71.89%,resulting in the relative abundance of Candidatus Brocadiaceae increased to 61.27%on day 180.The reactor operated steadily from days 444 to 498,maintaining the nitrogen removal rate(NRR)of 3.00 kgN/(m^(3)·d)and achieving successful sludge granulation with the particle size of 392.4μm.In short,this study provided a simple and efficient approach for enriching Anammox bacteria from the activated sludge,supporting to start an Anammox process efficiently.展开更多
Anaerobic digestion(AD)is widely employed for sludge stabilization and waste reduction.However,the slow hydrolysis process hinders methane production and leads to prolonged sludge issues.In this study,an efficient and...Anaerobic digestion(AD)is widely employed for sludge stabilization and waste reduction.However,the slow hydrolysis process hinders methane production and leads to prolonged sludge issues.In this study,an efficient and eco-friendly lysozyme pre-treatment method was utilized to address these challenges.By optimizing lysozyme dosage,hydrolysis and cell lysis were maximized.Furthermore,lysozyme combined with hydrothermal pretreatment enhanced overall efficiency.Results indicate that:(1)When lysozyme dosage reached 90 mg/g TS after 240 min of pretreatment,SCOD,soluble polysaccharides,and protein content reached their maxima at 855.00,44.09,and 204.86 mg/L,respectively.This represented an increase of 85.87%,365.58%,and 259.21%compared to the untreated sludge.Threedimensional fluorescence spectroscopy revealed the highest fluorescence intensity in the IV region(soluble microbial product),promoting microbial metabolic activity.(2)Lysozyme combined with hydrothermal pretreatment significantly increased SCOD,soluble proteins,and polysaccharide release from sludge,reducing SCOD release time.Orthogonal experiments identified Group 3 as the most effective for SCOD and soluble polysaccharide release,while Group 9 released the most soluble proteins.The significance order of factors influencing SCOD,soluble proteins,and polysaccharide release is hydrothermal temperature>hydrothermal time>enzymatic digestion time.(3)The lysozyme-assisted hydrothermal pretreatment group exhibited the fastest release and the highest SCOD concentration of 8,135.00 mg/L during anaerobic digestion.Maximum SCOD consumption and cumulative gas production increased by 95.89%and 130.58%,respectively,compared to the control group,allowing gas production to conclude 3 days earlier.展开更多
Saccharification of lignocellulosic wastes is the bottleneck of different bio-based chemical industries.Using enzymes for saccharification of lignocellulosic materials has several advantages over using chemicals.In th...Saccharification of lignocellulosic wastes is the bottleneck of different bio-based chemical industries.Using enzymes for saccharification of lignocellulosic materials has several advantages over using chemicals.In the current work,the application of the Maximyze■ enzyme system,which is industrially used in papermaking,was investigated in the saccharification of paper sludge and fiber dust wastes from the tissue paper industry.For optimizing the saccharification process,the effects of the consistency%,enzyme loading,and incubation time were studied and optimized using the Response Surface Methodology.The effect of these factors on the weight loss of paper sludge and total sugars in the hydrolyzate was studied.High-Performance Liquid Chromatography(HPLC)was used to measure the sugars composition of the hydrolyzate.Under the optimized conditions,~90% and~66% of the fiber dust and paper sludge could be hydrolyzed into sugars,respectively.The sugar composition was 80.23% glucose,10.99% xylose,and 8.65% arabinose based on the total sugars in the case of fiber dust.In comparison,80.63% glucose,8.43% xylose,and 10.75% arabinose were detected in the case of paper sludge.The results showed the applicability of the Maximyze Rcommercial enzymes used in the paper industry for efficient saccharification of paper sludge and fiber dust.The presence of non-cellulosic materials in the paper sludge(residual ink,paper additives,and ash)didn’t affect the activity of the enzymes.The study also showed the potential use of fiber dust as a valuable and clean source of sugars that can be used to prepare different bio-based chemicals.展开更多
Sewage sludge in cities of Yangzi River Belt,China,generally exhibits a lower organic content and higher silt contentdue to leakage of drainage system,which caused low bioenergy recovery and carbon emission benefits i...Sewage sludge in cities of Yangzi River Belt,China,generally exhibits a lower organic content and higher silt contentdue to leakage of drainage system,which caused low bioenergy recovery and carbon emission benefits in conventional anaerobic digestion(CAD).Therefore,this paper is on a pilot scale,a bio-thermophilic pretreatment anaerobic digestion(BTPAD)for low organic sludge(volatile solids(VS)of 4%)was operated with a long-term continuous flow of 200 days.The VS degradation rate and CH_(4) yield of BTPAD increased by 19.93%and 53.33%,respectively,compared to those of CAD.The analysis of organic compositions in sludge revealed that BTPAD mainly improved the hydrolysis of proteins in sludge.Further analysis of microbial community proportions by high-throughput sequencing revealed that the short-term bio-thermophilic pretreatment was enriched in Clostridiales,Coprothermobacter and Gelria,was capable of hydrolyzing acidified proteins,and provided more volatile fatty acid(VFA)for the subsequent reaction.Biome combined with fluorescence quantitative polymerase chain reaction(PCR)analysis showed that the number of bacteria with high methanogenic capacity in BTPAD was much higher than that in CAD during the medium temperature digestion stage,indicating that short-term bio-thermophilic pretreatment could provide better methanogenic conditions for BTPAD.Furthermore,the greenhouse gas emission footprint analysis showed that short-term bio-thermophilic pretreatment could reduce the carbon emission of sludge anaerobic digestion system by 19.18%.展开更多
Electroplating sludge(ES),a byproduct of the electroplating industry,is a significant environmental concern due to its high content of soluble heavy metals(HMs).The significance of spinel formation from ES lies in its...Electroplating sludge(ES),a byproduct of the electroplating industry,is a significant environmental concern due to its high content of soluble heavy metals(HMs).The significance of spinel formation from ES lies in its potential for HMs enrichment and environmental remediation,offering a sustainable solution for hazardous waste management.The article delves into themultifaceted recycling of HMs-rich spinel fromES,encompassing its synthesis,metal enrichment,and thermodynamic stability.The pyro-metallurgical and hydrometallurgical processes for spinel synthesis were discussed,with a focus on the critical role of thermodynamic data in predicting the stability and formation of spinel structures.The crystallographic and magnetic properties of spinels,with their applications in environmental remediation and energy storage are highlighted.The article provides a comprehensive reviewon the recycling of HMs-rich spinel fromES,offering a means to recycle HMs,mitigate ecological harm,and contribute to a circular economy through the recovery and application of valuable materials.The selective leaching of metals from ES also faces challenges,which was limited by the separation,purification steps and high energy consumption.This high energy consumption is a significant operational cost and also contributes to environmental concerns related to carbon emissions.It is essential to address the challenges through continued research and development,improved technologies,and supportive regulatory frameworks.展开更多
We read with great interest the investigations conducted by Pourakbar et al.(2024)on the“Stabilization of clay soil using alkali-activated sewage sludge.”The authors have investigated the feasibility of utilizing al...We read with great interest the investigations conducted by Pourakbar et al.(2024)on the“Stabilization of clay soil using alkali-activated sewage sludge.”The authors have investigated the feasibility of utilizing alkali-activated sewage sludge(AASS)as a binder for stabilizing the clayey soil.Sewage sludge(SS)in varying proportions of 1.5%,2%,2.5%,3.5%,and 4.5%was utilized to prepare geopolymer binders using sodium and potassium-based alkali activators.Furthermore,unconfined compressive strength(UCS)and direct shear tests were conducted to examine the strength development of clayey soil stabilized with AASS.While the study presented some intriguing results,we have identified critical concerns regarding(i)the selection of SS as a precursor for alkali activation,(ii)technical inconsistencies associated with the compaction characteristics and microstructural analysis,and(iii)the feasibility of the proposed methodology for practical applications.Through our discussion,we seek to highlight these issues and provide constructive feedback to advance the understanding of alkali activation processes and their implications for soil stabilization.展开更多
The study aims to investigate uranium species in the sediments of the natural-technogenic system within a sludge storage facility in Russia.The relevance of this work is underscored by the need to assess the geochemic...The study aims to investigate uranium species in the sediments of the natural-technogenic system within a sludge storage facility in Russia.The relevance of this work is underscored by the need to assess the geochemical mobility of radionuclides,a critical factor for predicting their migration and environmental impact.The objective of the research was to determine the uranium species in both peat and sedimentary rock samples of the sludge storage facility and the adjacent area.Laboratory analyses included XRD,XRF analysis using synchrotron radiation,and scanning electron microscopy to study the composition and properties of minerals.The uranium species were further identified using a modified Tessier sequential extraction method.The results revealed that uranium predominantly occurs in a stable silicate-bound form(up to 80%)in sedimentary rocks,indicating minimal geochemical mobility.In contrast,in peat deposits,uranium is primarily associated with manganese and iron oxides(30–60%)as well as organic matter(5–40%),with the most mobile forms constituting less than 5%.The decrease in uranium concentration with distance from the facility was attributed to sorption onto organic matter and co-precipitation with mineral compounds,manganese and iron oxides,which serve as effective natural sorbents.The findings highlight the critical role of organic matter and metal oxides in limiting uranium migration,thus identifying them as key components in the formation of natural barriers for radionuclides.These results are crucial for assessing environmental risks associated with radioactive waste management and for developing strategies to minimize the ecological impact of sludge storages.展开更多
Red anaerobic ammonia oxidation (Anammox) granular sludge (AnGS) has been reported insuccessfully operating Anammox systems, and its color is associated with sludge activity.However, in long-term operating systems, An...Red anaerobic ammonia oxidation (Anammox) granular sludge (AnGS) has been reported insuccessfully operating Anammox systems, and its color is associated with sludge activity.However, in long-term operating systems, AnGS exhibits different sensory colors, physicalstructures, community structures, and denitrification performance, but the relationship betweenthem has not yet been elucidated.The AnGS of the Anammox system, which has beenin operation for more than a decade, can be divided into twomain categories: red and white.The specific Anammox activity (SAA) in conventional red AnGS increased continuously asthe particle size increased from <0.51 mm to 6.02 ± 0.84 mm. The SAA of white AnGS wereslightly lower than those of red AnGS with similarly-size granules but significantly higherthan AnGS with smaller red granules. Compared with red AnGS, the extracellular polymericsubstances of white AnGS were significantly reduced,mainly due to the higher intracellulariron content, resulting in lower heme c concentration. Thus, heme c may prove not to bean evaluative tool for measuring Anammox activity. Red and white AnGS, whether throughself-aggregation or adsorption by hydroxyl apatite and other carriers, will face the fate ofinternal voids during particle size growth. White AnGS exhibited amore complex microbialcommunity than red AnGS. Candidatus Brocadia was abundant in red AnGS and the abundanceincreased with increasing granule size. Candidatus Kuenenia and Candidatus Jetteniamade significant contributions to denitrification in white AnGS. This study provides a newperspective on particle selection for anammox engineering applications.展开更多
Sedimentation sludge water(SSW),a prominent constituent of wastewater from drinking water treatment plants,has received limited attention in terms of its treatment and utilization likely due to the perceived difficult...Sedimentation sludge water(SSW),a prominent constituent of wastewater from drinking water treatment plants,has received limited attention in terms of its treatment and utilization likely due to the perceived difficulties associated with managing SSW sludge.This study comprehensively evaluated the water quality of SSW by comparing it to a well-documented wastewater(filter backwash water(FBW)).Furthermore,it investigated the pollutant variations in the SSW during pre-sedimentation process,probed the underlying reaction mechanism,and explored the feasibility of employing a pilot-scale coagulation-sedimentation process for SSW treatment.The levels of most water quality parameters were generally comparable between SSW and FBW.During the pre-sedimentation of SSW,significant removal of turbidity,bacterial counts,and dissolved organic matter(DOM)was observed.The characterization of DOM components,molecular weight distributions,and optical properties revealed that the macromolecular proteinaceous biopolymers and humic acids were preferentially removed.The characterization of particulates indicated that high surface energy,zeta potential,and bridging/adsorption/sedimentation/coagulation capacities in aluminum residuals of SSW,underscoring its potential as a coagulant and promoting the generation and sedimentation of inorganic-organic complexes.The coagulation-sedimentation process could effectively remove pollutants from low-turbidity SSW([turbidity]0<15 NTU).These findings provide valuable insights into the water quality dynamics of SSW during the pre-sedimentation process,facilitating the development of SSW quality management and enhancing its reuse rate.展开更多
Neodymium-iron-boron(Nd-Fe-B)sludge is an important secondary resource of rare-earth elements(REEs).However,the state-of-the-art recycling method,i.e.,HCl-preferential dissolution faces challenges such as slow leachin...Neodymium-iron-boron(Nd-Fe-B)sludge is an important secondary resource of rare-earth elements(REEs).However,the state-of-the-art recycling method,i.e.,HCl-preferential dissolution faces challenges such as slow leaching kinetics,excessive chemical consumption and wastewater generation.In this work,the in situ anodic leaching of Nd-Fe-B sludge was developed to selectively recover REEs with high efficiency.The leaching rates of the REEs are 2.4-9.0 times higher using the in situ anodic leaching at the current density from 10 to 40 mA/cm^(2)than using conventional chemical leaching under the maintained pH of 3.7.Mechanism studies reveal that the anode-generated H~+plays the key role during the in situ anodic leaching process that locally increases the H^(+)concentration at the interface of sludge particles,accele rating the leaching kinetics.By achieving a total leaching efficiency of Nd-Fe-B sludge close to 100%and the Fe deposition efficiency in the range of 70.9%-74.3%,selective leaching of REEs is successfully realized and thus largely reduces chemical consumption.Additionally,a two-step recycling route involving electrolysis-selective precipitation was proposed that enables a stable REEs recovery of 92.2%with recyclable electrolyte.This study provides a novel and environmentally-friendly strategy for the efficient recovery of REEs from secondary resources.展开更多
This paper investigated the use of magnesium phosphate cement (MPC) for solidifying sludge with different humic acid (HA) content (ranging from 0 to 4.5%) and explored the solidification mechanism. Fluidity, setting t...This paper investigated the use of magnesium phosphate cement (MPC) for solidifying sludge with different humic acid (HA) content (ranging from 0 to 4.5%) and explored the solidification mechanism. Fluidity, setting time, unconfined compressive strength (UCS), the strength formation mechanism, and the spontaneous imbibition process of solidified sludge (SS) were studied. The results indicate that MPC can be used as a low-alkalinity curing agent. As the HA content increases, fluidity and setting time also increase, while hydration temperature and strength decrease. Additionally, the failure mode of SS transitions from brittleness to ductility. The strength of SS is composed of the cementation strength provided by MPC hydration products, matric suction, osmotic suction, and the structural strength of the sludge. MPC reduces the structural strength caused by the shrinkage of pure sludge under the action of matric suction, but the incorporation of MPC significantly improved the strength when the sludge is eroded by water. X-ray diffraction (XRD) and scanning electron microscopy (SEM) show that the sludge and MPC can form a dense solid body, forming various hydration products, and synergistically improve the mechanical properties of the sludge.展开更多
基金supported by National Natural Science Foundation of China(Nos.52370025,22176012)BUCEA Post Graduate Innovation Project(No.PG2024086)。
文摘Sludge,the massive by-product of the sewage system,became a major challenge for the wastewater treatment industry.Yet,conventional methods often face challenges like low efficiency,high energy consumption,and environmental pollution.Especially,the improper treatment and disposal of toxic sludge generated from different industrial processes or specific wastewater treatment operations exerted significant pressure and threat to hydrosphere,pedosphere,atmosphere and even biosphere.
基金supported by the Opening Project of National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology,and the National Natural Science Foundation of China(No.52270017).
文摘The organic compound composition ofwastewater,serves as a crucial indicator for the operational performance of activated sludge processes and has a major influence on the development of filamentous bulking in activated sludge.This study focused on the impact of typical soluble and slowly-biodegradable organic compounds,investigating the pathways through which these substrates affect the occurrence of filamentous bulking in systems operated under both high-and low-oxygen conditions.Results showed that slowly-biodegradable organic compounds lead to a concentrated distribution of microorganisms within flocs,with inward growth of filamentous bacteria.Both Tween-80 and granular starch treated systems exhibited a significant increase in protein content.The glucose system,utilizing soluble substrates,exhibited a markedly higher total polysaccharide content.Microbial communities in the Tween-80 and granular starch treated systems were characterized by a higher abundance of bacteria known to enhance sludge flocculation and settling,such as Competibacter,Xanthomonadaceae and Zoogloea.These findings are of high significance for controlling the operational performance and stability of activated sludge systems,deepening our understanding and providing a novel perspective for the improvement of wastewater treatment processes.
基金supported by the National Key Research and Development Program of China(2019YFA0705800)the National Natural Science Foundation of China(52030001)the Science&Technology Commission of Shanghai Municipality(20dz1207600).
文摘Drying operations are of grave importance to realize the reduction and utilization of sewage sludge resources,but the conventional thermal evaporation drying(TED)technology presents challenges due to the need for a large amount of thermal energy to conquer the phase-change latent heat of moisture.Herein,we report a non-phase change technology based on particle high-speed self-rotation in a cyclone for fast,low-temperature drying of viscous sludge with high-moisture contents.Dispersed phase medium(DPM)is introduced into the cyclone self-rotation drying(CSRD)reactor to enhance the dispersion of the viscous sludge.The effects of carrier gas temperature,feeding rate,size,and proportion of DPM particles in the drying process are systematically examined.Under optimal operating conditions,the weighted content of moisture in the viscous sludge could be reduced from 80%to 15.01%in less than 5 s,achieving a high drying efficiency of 95.79%.Theoretical calculations also reveal that 89.26%of the moisture is removed through non-phase change pathway,contributing to a 522-fold increase in the drying rate of CSRD compared to TED technology.This investigation presents a sustainable effective approach for high moisture viscous sludge treatment with low energy consumption and carbon emissions.
基金Funded by the National Nature Science Foundation of China(Nos.51978439,52278269,52278268,and 52108238)the Tianjin Outstanding Young Scholars Science Fund Project(No.22JCJQJC00020)the State Key Laboratory of Green Building Materials Open Foundation(No.2021GBM08)。
文摘We examined the enhancing effects of different dosages of product of Centrifugation of Bacterial Liquid(product of CBL)on the performance of slag-fGD gypsum-cement-bentonite-sludge system using MICP technology.We analyzed the multifaceted performance of the solidified sludge from macroscopic and microscopic perspectives.The experimental results reveal that the increase in product of CBL dosage results in positive impacts on the solidified sludge,including higher side compressive strength,lower leachate heavy metal concentration,and improved crack repair rates.At a 0.4%product of CBL doping concentration,the strength of the solidified sludge is enhanced by 26.6%at 3 d,61.2%at 7 d,and 13.9%at 28 d when compared to the unmodified solidified sludge.After 28 days,the concentrations of Zn and Cu ions reduce by 58%and 18%,respectively,and the crack repair rate is 58.4%.These results demonstrate that the increase in heavy metal concentration in the leachate leads to an increase in the strength of the solidified sludge.The strengthening procedure heavily relies on the mineralisation reaction of Bacillus pasteurii,which produces a substantial amount of CaCO_(3)to cement the particles and fill the pores initially.The modified solidifying sludge exhibits a self-repairing effect and an enhanced multifaceted performance as a result of oxygen being restored after crack formation and reactivation of Bacillus pasteurii.Such conditions facilitate the body's recovery.
文摘This study investigates the innovative reuse of sewage sludge with eco-friendly alkaline solutes to improve clayey soil without conventional cementitious binders.The unconfined compressive strength(UCS)was the main criterion to assess the quality and effectiveness of the proposed solutions,as this test was performed to measure the strength of the stabilized clay by varying binders’dosages and curing times.Moreover,the direct shear test(DST)was used to investigate the Mohr-Coulomb parameters of the treated soil.Microstructure observations of the natural and treated soil were conducted using scanning electron microscope(SEM),energy-dispersive spectroscopy(EDS),and FTIR.Furthermore,toxicity characteristic leaching procedure(TCLP)tests were performed on the treated soil to investigate the leachability of metals.According to the results,using 2.5%of sewage sludge activated by NaOH and Na_(2)SiO_(3)increases the UCS values from 176 kPa to 1.46 MPa after 7 d and 56 d of curing,respectively.The results of the DST indicate that sewage sludge as a precursor increases cohesion and enhances frictional resistance,thereby improving the Mohr-Coulomb parameters of the stabilized soil.The SEM micrographs show that alkali-activated sewage sludge increases the integrity and reduces the cavity volumes in the stabilized soil.Moreover,TCLP tests revealed that the solubility of metals in the treated soil alkaliactivated by sewage sludge significantly decreased.This study suggests that using sewage sludge can replace cement and lime in ground improvement,improve the circular economy,and reduce the carbon footprint of construction projects.
基金supported by the Guangdong Special Support ProgramProject(No.2021JC060580)the Foshan Innovation Team Project(No.2130218003140).
文摘In this study,the effects of different salinity gradients and addition of compatible solutes on anaerobic treated effluent water qualities,sludge characteristics and microbial communities were investigated.The increase in salinity resulted in a decrease in particle size of the granular sludge,which was concentrated in the range of 0.5-1.0 mm.The content of EPS(extracellular polymeric substances)in the granular sludge gradually increased with increasing salinity and the addition of betaine(a typical compatible solute).Meanwhile,the microbial community structure was significantly affected by salinity,with high salinity reducing the diversity of bacteria.At higher salinity,Patescibacteria and Proteobacteria gradually became the dominant phylum,with relative abundance increasing to 13.53%and 12.16%at 20 g/L salinity.Desulfobacterota and its subordinate Desulfovibrio,which secrete EPS in large quantities,dominated significantly after betaine addition.Their relative abundance reached 13.65%and 7.86%at phylum level and genus level.The effect of these changes on the treated effluent was shown as the average chemical oxygen demand(COD)removal rate decreased from 82.10%to 79.71%,78.01%,68.51%and 64.55%when the salinity gradually increased from 2 g/L to 6,10,16 and 20 g/L.At the salinity of 20 g/L,average COD removal increased to 71.65%by the addition of 2 mmol/L betaine.The gradient elevated salinity and the exogenous addition of betaine played an important role in achieving stability of the anaerobic system in a highly saline environment,which provided a feasible strategy for anaerobic treatment of organic saline wastewater.
文摘The development of sustainable sludge management systems requires looking at them with a new vision in which the concepts of SD(Sustainable Development)must integrate those of CE(Circular Economy),both concepts subject to the principles of TD(Thermodynamics),thus allowing the adoption of actions that are all the more effective the more complete the evaluation of the social dimension has been.This involves a new“Way of thinking”which sees the sludge system as the“Locomotive”of the entire wastewater/sludge treatment train and is developed through“Ways of acting”which includes both“Technical”actions to maximize recoveries of useful materials and/or or energy,and“Socio/Institutional”actions to overcome barriers linked to local cultures and traditions,also considering that the specific local context heavily influences the choices capable of satisfying the concepts of CE.It follows the need of issuing realistic and applicable regulations and overcoming social barriers,such as lack of infrastructure and/or qualified personnel,to achieve an effective integration of the concepts of CE with the more general ones of sustainability.
基金supported by Shanghai Pujiang Program(No.22PJD001)the Fundamental Research Funds for the Central Universities(No.2232021G-11).
文摘Catalytic oxidation of NO at room temperature was carried out over nitrogen(N)-doped sludge char(SC)prepared from pyrolysis ofmunicipal sewage sludge,and urea was adopted as nitrogen source.The effects of different N-doping methods(one-step and two-step method),dried sludge(DS)/urea mass ratios(5:1,4:1,3:1,2:1,and 1:1),SC preparation procedures(pyrolysis only,pyrolysis with acid washing,and pyrolysis with KOH activation and acid washing),and different pyrolysis temperatures(500,600,700,and 800°C)on the catalytic oxidation of NO were compared to optimize the procedure for SC preparation.The results indicated that N-doping could obviously promote the catalytic performance of SC.The one-step method with simultaneous sludge pyrolysis(at 700°C),KOH activation,and N-doping(DS/urea of 3:1)was the optimal procedure for preparing the N-doped SC with the NO conversion rate of 54.7%,whereas the optimal NO conversion rate of SC without N-doping was only 47.3%.Urea worked both as carbon and nitrogen source,which could increase about 2.9%-16.5%of carbon and 24.8%-42.7%of nitrogen content in SC pyrolyzed at 700°C.N-doping significantly promoted microporosity of SC.The optimal N-doped SC showed specific surface areas of 571.38 m^(2)/g,much higher than 374.34 m^(2)/g of the optimal SC without N-doping.In addition,N-doping also increased amorphousness and surface basicity of SC through the formation of N-containing groups.Finally,three reaction paths,i.e.microporous reactor,active sites,and basic site control path,were proposed to explain the mechanism of N-doping on promoting the catalytic performance of NO.
基金Project supported by the National Natural Science Foundation of China(52261037,52401251)Key Research Project of Jiangxi Province(20203ABC28W006)+2 种基金the Research Fund of Key Laboratory of Rare Earths,Chinese Academy of SciencesKey Laboratory of Ionic Rare Earth Re sources and Environment,Ministry of Natural Resources of the People's Republic of China(2022IRERE302)the Ganzhou Science and Technology Innovation Empowerment Youth"Jie bang Gua shuai"Project。
文摘Recovery of rare earth elements(REEs)from bulk Nd-Fe-B scrap by chlorination with NH_(4)Cl as a chlorinating agent has been reported to be an energy efficient and environmentally friendly method.However,the reaction mechanism and phase evolution of the low-temperature selective chlorination process of Nd-Fe-B sludge are not clear.In this paper,we systematically investigated the lowtemperature selective chlorination process of Nd-Fe-B sludge with NH4Cl by combining thermokinetic theoretical calculations and experiments,and revealed its reaction mechanism.The phase evolution during chlorination was determined by X-ray diffraction(XRD),scanning electron microscopy(SEM)and ene rgy-dispersive X-ray spectroscopy(EDS)characterization as well as co mputational analysis of the phase stability diagram of the M-O-Cl system.To determine the optimum chlorination conditions,the effects of chlorinating agent dosage,reaction temperature and reaction time on the reaction were investigated.The results show that the rare earth components in Nd-Fe-B sludge are selectively chlorinated to RECl3and the formation of REOCl is avoided in the temperature range of 300-420℃,while the iron components are preferentially oxidized to Fe2O3.The selective chlorination reaction is consistent with the unreacted shrinking core model,and the rate-controlling step of the reaction is the internal diffusion process of NH4Cl through the transition layer of the reactant product to the surface of the Nd-Fe-B sludge.The complete chlorination of REEs is successfully achieved and 99.8%of REEs are selectively extracted into the leaching solution under optimal chlorination conditions(300℃,2.5 times of stoichiometric amount,4 h).
基金supported by the National Natural Science Foundation of China(No.52070149)Shaanxi Innovative Research Team for Key Science and Technology(No.2023-CXTD-36)+1 种基金Shaanxi Province Key Program for International S&T Cooperation Projects(No.2024GH-ZDXM-04)the Bureau of Science and Technology of Xi’an City of China(No.23SFSF0011).
文摘Anaerobic ammonia oxidation(Anammox)is an economical and sustainablewastewater nitrogen removal technology,and its application in the mainstream process is the inevitable trend of the development of Anammox.However,how to effectively enriching Anammox bacteria from the activated sludge remains challenging and restricts its extensive applications.In this study,the rapid and efficient enrichment of Anammox bacteriawas achieved by raising the reflux ratio and nitrogen loading rate(NLR)using conventional activated sludge as the inoculant.In the screening phase(days 1–90),the reflux ratio was increased to discharge partial floc sludge,resulting in the relative abundance of Candidatus Brocadiaceae increased from0.04%to 22.54%,which effectively reduced thematrix and spatial competition between other microorganisms and Anammox bacteria.On day 90,the stoichiometric ratio of the Anammox process closely approached the theoretical value of 1:1.32:0.26,indicating that the Anammox reaction was the primary nitrogen removal process in the system.In the enrichment phase(days 91–238),the NLR increased from 0.43 to 1.20 kgN/(m^(3)·d)and removal efficiency was 71.89%,resulting in the relative abundance of Candidatus Brocadiaceae increased to 61.27%on day 180.The reactor operated steadily from days 444 to 498,maintaining the nitrogen removal rate(NRR)of 3.00 kgN/(m^(3)·d)and achieving successful sludge granulation with the particle size of 392.4μm.In short,this study provided a simple and efficient approach for enriching Anammox bacteria from the activated sludge,supporting to start an Anammox process efficiently.
文摘Anaerobic digestion(AD)is widely employed for sludge stabilization and waste reduction.However,the slow hydrolysis process hinders methane production and leads to prolonged sludge issues.In this study,an efficient and eco-friendly lysozyme pre-treatment method was utilized to address these challenges.By optimizing lysozyme dosage,hydrolysis and cell lysis were maximized.Furthermore,lysozyme combined with hydrothermal pretreatment enhanced overall efficiency.Results indicate that:(1)When lysozyme dosage reached 90 mg/g TS after 240 min of pretreatment,SCOD,soluble polysaccharides,and protein content reached their maxima at 855.00,44.09,and 204.86 mg/L,respectively.This represented an increase of 85.87%,365.58%,and 259.21%compared to the untreated sludge.Threedimensional fluorescence spectroscopy revealed the highest fluorescence intensity in the IV region(soluble microbial product),promoting microbial metabolic activity.(2)Lysozyme combined with hydrothermal pretreatment significantly increased SCOD,soluble proteins,and polysaccharide release from sludge,reducing SCOD release time.Orthogonal experiments identified Group 3 as the most effective for SCOD and soluble polysaccharide release,while Group 9 released the most soluble proteins.The significance order of factors influencing SCOD,soluble proteins,and polysaccharide release is hydrothermal temperature>hydrothermal time>enzymatic digestion time.(3)The lysozyme-assisted hydrothermal pretreatment group exhibited the fastest release and the highest SCOD concentration of 8,135.00 mg/L during anaerobic digestion.Maximum SCOD consumption and cumulative gas production increased by 95.89%and 130.58%,respectively,compared to the control group,allowing gas production to conclude 3 days earlier.
基金funding of the current work by the Science,Technology,and Innovation Funding Authority(STDF),Egypt,project no.46104:“Recycling of sludge wastes from paper industry via green technologies”.
文摘Saccharification of lignocellulosic wastes is the bottleneck of different bio-based chemical industries.Using enzymes for saccharification of lignocellulosic materials has several advantages over using chemicals.In the current work,the application of the Maximyze■ enzyme system,which is industrially used in papermaking,was investigated in the saccharification of paper sludge and fiber dust wastes from the tissue paper industry.For optimizing the saccharification process,the effects of the consistency%,enzyme loading,and incubation time were studied and optimized using the Response Surface Methodology.The effect of these factors on the weight loss of paper sludge and total sugars in the hydrolyzate was studied.High-Performance Liquid Chromatography(HPLC)was used to measure the sugars composition of the hydrolyzate.Under the optimized conditions,~90% and~66% of the fiber dust and paper sludge could be hydrolyzed into sugars,respectively.The sugar composition was 80.23% glucose,10.99% xylose,and 8.65% arabinose based on the total sugars in the case of fiber dust.In comparison,80.63% glucose,8.43% xylose,and 10.75% arabinose were detected in the case of paper sludge.The results showed the applicability of the Maximyze Rcommercial enzymes used in the paper industry for efficient saccharification of paper sludge and fiber dust.The presence of non-cellulosic materials in the paper sludge(residual ink,paper additives,and ash)didn’t affect the activity of the enzymes.The study also showed the potential use of fiber dust as a valuable and clean source of sugars that can be used to prepare different bio-based chemicals.
基金supported by the National Key Research and Development Project (Nos.2020YFC1908702 and 2021YFC3200700)the National Natural Science Foundation of China (Nos.52192684 and 52192680).
文摘Sewage sludge in cities of Yangzi River Belt,China,generally exhibits a lower organic content and higher silt contentdue to leakage of drainage system,which caused low bioenergy recovery and carbon emission benefits in conventional anaerobic digestion(CAD).Therefore,this paper is on a pilot scale,a bio-thermophilic pretreatment anaerobic digestion(BTPAD)for low organic sludge(volatile solids(VS)of 4%)was operated with a long-term continuous flow of 200 days.The VS degradation rate and CH_(4) yield of BTPAD increased by 19.93%and 53.33%,respectively,compared to those of CAD.The analysis of organic compositions in sludge revealed that BTPAD mainly improved the hydrolysis of proteins in sludge.Further analysis of microbial community proportions by high-throughput sequencing revealed that the short-term bio-thermophilic pretreatment was enriched in Clostridiales,Coprothermobacter and Gelria,was capable of hydrolyzing acidified proteins,and provided more volatile fatty acid(VFA)for the subsequent reaction.Biome combined with fluorescence quantitative polymerase chain reaction(PCR)analysis showed that the number of bacteria with high methanogenic capacity in BTPAD was much higher than that in CAD during the medium temperature digestion stage,indicating that short-term bio-thermophilic pretreatment could provide better methanogenic conditions for BTPAD.Furthermore,the greenhouse gas emission footprint analysis showed that short-term bio-thermophilic pretreatment could reduce the carbon emission of sludge anaerobic digestion system by 19.18%.
基金supported by the National Natural Science Foundation of China(Nos.52370158 and 22006053)Guangzhou Science and Technology Plan Project(No.2024A04J0821)Guangdong Provincial Education Science Planning Project(Higher Education Special Project)(No.2023GXJK108).
文摘Electroplating sludge(ES),a byproduct of the electroplating industry,is a significant environmental concern due to its high content of soluble heavy metals(HMs).The significance of spinel formation from ES lies in its potential for HMs enrichment and environmental remediation,offering a sustainable solution for hazardous waste management.The article delves into themultifaceted recycling of HMs-rich spinel fromES,encompassing its synthesis,metal enrichment,and thermodynamic stability.The pyro-metallurgical and hydrometallurgical processes for spinel synthesis were discussed,with a focus on the critical role of thermodynamic data in predicting the stability and formation of spinel structures.The crystallographic and magnetic properties of spinels,with their applications in environmental remediation and energy storage are highlighted.The article provides a comprehensive reviewon the recycling of HMs-rich spinel fromES,offering a means to recycle HMs,mitigate ecological harm,and contribute to a circular economy through the recovery and application of valuable materials.The selective leaching of metals from ES also faces challenges,which was limited by the separation,purification steps and high energy consumption.This high energy consumption is a significant operational cost and also contributes to environmental concerns related to carbon emissions.It is essential to address the challenges through continued research and development,improved technologies,and supportive regulatory frameworks.
文摘We read with great interest the investigations conducted by Pourakbar et al.(2024)on the“Stabilization of clay soil using alkali-activated sewage sludge.”The authors have investigated the feasibility of utilizing alkali-activated sewage sludge(AASS)as a binder for stabilizing the clayey soil.Sewage sludge(SS)in varying proportions of 1.5%,2%,2.5%,3.5%,and 4.5%was utilized to prepare geopolymer binders using sodium and potassium-based alkali activators.Furthermore,unconfined compressive strength(UCS)and direct shear tests were conducted to examine the strength development of clayey soil stabilized with AASS.While the study presented some intriguing results,we have identified critical concerns regarding(i)the selection of SS as a precursor for alkali activation,(ii)technical inconsistencies associated with the compaction characteristics and microstructural analysis,and(iii)the feasibility of the proposed methodology for practical applications.Through our discussion,we seek to highlight these issues and provide constructive feedback to advance the understanding of alkali activation processes and their implications for soil stabilization.
基金supported by the Russian Science Foundation grant number 23-27-00362,https://rscf.ru/en/project/23-27-00362/.
文摘The study aims to investigate uranium species in the sediments of the natural-technogenic system within a sludge storage facility in Russia.The relevance of this work is underscored by the need to assess the geochemical mobility of radionuclides,a critical factor for predicting their migration and environmental impact.The objective of the research was to determine the uranium species in both peat and sedimentary rock samples of the sludge storage facility and the adjacent area.Laboratory analyses included XRD,XRF analysis using synchrotron radiation,and scanning electron microscopy to study the composition and properties of minerals.The uranium species were further identified using a modified Tessier sequential extraction method.The results revealed that uranium predominantly occurs in a stable silicate-bound form(up to 80%)in sedimentary rocks,indicating minimal geochemical mobility.In contrast,in peat deposits,uranium is primarily associated with manganese and iron oxides(30–60%)as well as organic matter(5–40%),with the most mobile forms constituting less than 5%.The decrease in uranium concentration with distance from the facility was attributed to sorption onto organic matter and co-precipitation with mineral compounds,manganese and iron oxides,which serve as effective natural sorbents.The findings highlight the critical role of organic matter and metal oxides in limiting uranium migration,thus identifying them as key components in the formation of natural barriers for radionuclides.These results are crucial for assessing environmental risks associated with radioactive waste management and for developing strategies to minimize the ecological impact of sludge storages.
基金supported by the National Key Research and Development Programme of China(No.2023YFC3206903)the Natural Science Foundation of China(No.51938010)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.SJCX23_1717).
文摘Red anaerobic ammonia oxidation (Anammox) granular sludge (AnGS) has been reported insuccessfully operating Anammox systems, and its color is associated with sludge activity.However, in long-term operating systems, AnGS exhibits different sensory colors, physicalstructures, community structures, and denitrification performance, but the relationship betweenthem has not yet been elucidated.The AnGS of the Anammox system, which has beenin operation for more than a decade, can be divided into twomain categories: red and white.The specific Anammox activity (SAA) in conventional red AnGS increased continuously asthe particle size increased from <0.51 mm to 6.02 ± 0.84 mm. The SAA of white AnGS wereslightly lower than those of red AnGS with similarly-size granules but significantly higherthan AnGS with smaller red granules. Compared with red AnGS, the extracellular polymericsubstances of white AnGS were significantly reduced,mainly due to the higher intracellulariron content, resulting in lower heme c concentration. Thus, heme c may prove not to bean evaluative tool for measuring Anammox activity. Red and white AnGS, whether throughself-aggregation or adsorption by hydroxyl apatite and other carriers, will face the fate ofinternal voids during particle size growth. White AnGS exhibited amore complex microbialcommunity than red AnGS. Candidatus Brocadia was abundant in red AnGS and the abundanceincreased with increasing granule size. Candidatus Kuenenia and Candidatus Jetteniamade significant contributions to denitrification in white AnGS. This study provides a newperspective on particle selection for anammox engineering applications.
基金supported by the Ministry of Science and Technology of China (Nos.2021YFC3200904,and 2022YFC3203705)the National Natural Science Foundation of China (Nos.52070184,and 52270012)the Nanning Scientific Research and Technology Development Project (No.ZC20223238).
文摘Sedimentation sludge water(SSW),a prominent constituent of wastewater from drinking water treatment plants,has received limited attention in terms of its treatment and utilization likely due to the perceived difficulties associated with managing SSW sludge.This study comprehensively evaluated the water quality of SSW by comparing it to a well-documented wastewater(filter backwash water(FBW)).Furthermore,it investigated the pollutant variations in the SSW during pre-sedimentation process,probed the underlying reaction mechanism,and explored the feasibility of employing a pilot-scale coagulation-sedimentation process for SSW treatment.The levels of most water quality parameters were generally comparable between SSW and FBW.During the pre-sedimentation of SSW,significant removal of turbidity,bacterial counts,and dissolved organic matter(DOM)was observed.The characterization of DOM components,molecular weight distributions,and optical properties revealed that the macromolecular proteinaceous biopolymers and humic acids were preferentially removed.The characterization of particulates indicated that high surface energy,zeta potential,and bridging/adsorption/sedimentation/coagulation capacities in aluminum residuals of SSW,underscoring its potential as a coagulant and promoting the generation and sedimentation of inorganic-organic complexes.The coagulation-sedimentation process could effectively remove pollutants from low-turbidity SSW([turbidity]0<15 NTU).These findings provide valuable insights into the water quality dynamics of SSW during the pre-sedimentation process,facilitating the development of SSW quality management and enhancing its reuse rate.
基金Project supported by the Natural Science Foundation of Inner Mongolia Autonomous Region of China(2021BS02007,2022MS02014)the"Science and Technology Project of Ordos"Program(2021 CGI 17-9,2021 ZDI11-14)+2 种基金the National Natural Science Foundation of China(21971129,21961022,51903125,21661023)the"Inner Mongolia Autonomous Region 2022 Leading Talent Team of Science and Technology"Program(2022LJRC0008)China Postdoctoral Science Foundation(2018M640043,2019T120038)。
文摘Neodymium-iron-boron(Nd-Fe-B)sludge is an important secondary resource of rare-earth elements(REEs).However,the state-of-the-art recycling method,i.e.,HCl-preferential dissolution faces challenges such as slow leaching kinetics,excessive chemical consumption and wastewater generation.In this work,the in situ anodic leaching of Nd-Fe-B sludge was developed to selectively recover REEs with high efficiency.The leaching rates of the REEs are 2.4-9.0 times higher using the in situ anodic leaching at the current density from 10 to 40 mA/cm^(2)than using conventional chemical leaching under the maintained pH of 3.7.Mechanism studies reveal that the anode-generated H~+plays the key role during the in situ anodic leaching process that locally increases the H^(+)concentration at the interface of sludge particles,accele rating the leaching kinetics.By achieving a total leaching efficiency of Nd-Fe-B sludge close to 100%and the Fe deposition efficiency in the range of 70.9%-74.3%,selective leaching of REEs is successfully realized and thus largely reduces chemical consumption.Additionally,a two-step recycling route involving electrolysis-selective precipitation was proposed that enables a stable REEs recovery of 92.2%with recyclable electrolyte.This study provides a novel and environmentally-friendly strategy for the efficient recovery of REEs from secondary resources.
基金This research work was financially supported by the National Natural Science Foundation of China(Grant No.51972209).
文摘This paper investigated the use of magnesium phosphate cement (MPC) for solidifying sludge with different humic acid (HA) content (ranging from 0 to 4.5%) and explored the solidification mechanism. Fluidity, setting time, unconfined compressive strength (UCS), the strength formation mechanism, and the spontaneous imbibition process of solidified sludge (SS) were studied. The results indicate that MPC can be used as a low-alkalinity curing agent. As the HA content increases, fluidity and setting time also increase, while hydration temperature and strength decrease. Additionally, the failure mode of SS transitions from brittleness to ductility. The strength of SS is composed of the cementation strength provided by MPC hydration products, matric suction, osmotic suction, and the structural strength of the sludge. MPC reduces the structural strength caused by the shrinkage of pure sludge under the action of matric suction, but the incorporation of MPC significantly improved the strength when the sludge is eroded by water. X-ray diffraction (XRD) and scanning electron microscopy (SEM) show that the sludge and MPC can form a dense solid body, forming various hydration products, and synergistically improve the mechanical properties of the sludge.
