In order to explore the effects of CaO,lignite dust and sawdust on the drying characteristics ofmunicipal sludge at different concentrations,a three-factor three-level regression experiment was carried out based on th...In order to explore the effects of CaO,lignite dust and sawdust on the drying characteristics ofmunicipal sludge at different concentrations,a three-factor three-level regression experiment was carried out based on the results of thermogravimetric experiment and single factor experiment.By fitting three common mathematical models,the Page model with the highest fitting degree was selected to determine the most suitable mathematical model to describe the municipal sludge drying process.In addition,the Box-Behnken design principle in the response surface method was used to analyze the interaction of three factors on the drying characteristics of municipal sludge.The results of the study show that below 100℃is the optimal drying temperature range for municipal sludge.The results of single factor experiments showed that the order of influence of the three factors on sludge drying time was CaO concentration>sawdust concentration>lignite dust concentration.In the single factor experiment,the optimal process parameterswere CaOconcentration 3%,lignite powder concentration 7%,and sawdust concentration 7%.In themulti-factor interaction analysis,the interaction between CaO and sawdust had the most significant effect on the reduction of drying time,and the order of influence was as follows:CaO interaction with sawdust>lignite dust interaction with sawdust>CaO interaction with lignite powder.Further analysis showed that the optimal process ratio was 3%CaO concentration and 3%sawdust concentration.展开更多
Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the o...Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the occurrence of Be in BCS is unclear,which seriously hinders the development of pollution control technologies.In order to enhance the understanding of BCS,the occurrence of Be and the microscale interactions with coexisting phases were investigated for the first time.It was found that CaSO_(4)·2H_(2)O and amorphous SiO_(2) are the primary phases of BCS.The simulated experiments of purified materials showed that Be interacted with CaSO_(4)·2H_(2)O and amorphous SiO_(2).Be can enter into the lattice of CaSO_(4)·2H_(2)O mainly as free Be2+.Amorphous SiO_(2) can adsorb Be2+particularly at a pH range of 3–5.The dissolution behavior experiment of BCS shows that about 52%of the Be is readily extracted under acidic conditions,which refers to the Be of independent occurrence.In contrast,the remaining 48%of Be can be extracted only after the CaSO_(4)·2H_(2)O has completely dissolved.Hence,CaSO_(4)·2H_(2)O is identified as the key occurrence phase which determines the highly efficient dissolution of Be.As a result,this study enhances the understanding of BCS and lays the foundation for the development of Be separation technologies.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
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
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
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
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
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
Leachate sludge,a byproduct of municipal solid waste leachate treated through biochemical processes,is characterized by high water content(761.1%)and significant organic matter content(71.2%).Cement that is commonly u...Leachate sludge,a byproduct of municipal solid waste leachate treated through biochemical processes,is characterized by high water content(761.1%)and significant organic matter content(71.2%).Cement that is commonly used for solidifying leachate sludge has shown limited effectiveness.To address this issue,an alkali-activated ground-granulated blast-furnace slag(GGBS)geopolymer blended with polypropylene fibers was developed to solidify leachate sludge.Moreover,unconfined compressive strength(UCS),immersion,as well as X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and scanning electron microscope(SEM)tests were conducted to investigate the solidification effect and mechanism of the GGBS-based geopolymer and fibers on leachate sludge.The results showed that:the 28-d UCS of the solidified sludge with 20%and 30%GGBS is 0.35 MPa and 1.85 MPa,and decreases to 0.18 MPa and 1.13 MPa,respectively,after soaked in water for 28 d.Notably,the UCS of the solidified sludge with 30%GGBS satisfied the strength requirement of roadbed materials.Polypropylene fibers significantly enhanced the strength,ductility and water stability of the solidified sludge,with an optimal fiber content of 0.3%.Alkali-activated GGBS geopolymer generated three-dimensional,cross-linked geopolymeric gels within the solidified sludge,cementing sludge particles and filling intergranular pores to form a stable cementitious structure,thereby achieving effective solidification.Furthermore,incorporating polypropylene fibers improved the bonding and anchoring effect between fiber and solidified sludge,constrained lateral deformation of the solidified sludge,restricted crack propagation,and enhanced engineering performance of the solidified leachate sludge.展开更多
The removal of harmful cyanobacterial blooms(HCBs)and reuse of the resulting algal sludge are pressing issues in current environmental governance and ecological conservation.Aiming at tackling the abovementioned chall...The removal of harmful cyanobacterial blooms(HCBs)and reuse of the resulting algal sludge are pressing issues in current environmental governance and ecological conservation.Aiming at tackling the abovementioned challenges,titanium(Ti)-based coagulants are promising candidates.However,most of them suffer from poor stability and weak actual algal removal ability,and recycling of the algal sludge usually produces titanium dioxide(TiO_(2))with low photocatalytic ability.In this work,a lanthanum(La)-modified polytitanium chloride(La-PTC)coagulant is reported.La in the La-PTC coagulant serves a"kill two birds with one stone"strategy in algae removal and algae sludge reuse.Owing to the introduction of La ions,the La-PTC coagulant exhibits ultra-high stability and excellent algae removal capability with an efficiency of 98.71%,which is 7.25%higher than that of PTC coagulant.Moreover,recycling algae sludge can prepare high catalytic(2.45 times the commercial P25 TiO_(2))La/C-TiO_(2),where the presence of La enhances its visible light response range and inhibits electron hole recombination.The strategy of this La modified coagulant can not only achieve efficient re moval of HCBs,but also transfo rm the recovered algal sludge into photocatalysts with higher catalytic capacity.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
The resource utilization of sludge can effectively achieve the regeneration and utilization of resources,and promote sustainable economic development.Sludge carbonization is a sludge treatment and disposal technology ...The resource utilization of sludge can effectively achieve the regeneration and utilization of resources,and promote sustainable economic development.Sludge carbonization is a sludge treatment and disposal technology with broad application prospects,and its products have shown significant resource potential in land use,fuel utilization,and other fields.At present,China still faces some challenges in the resource utilization of sludge carbonization,such as issues related to heavy metal stability and outdated standards.In the future,it is necessary to further strengthen research,improve the standard system,and promote the widespread application of sludge carbonization technology,so as to achieve the goals of sludge reduction,harmlessness,and resource utilization and support the development of circular economy.展开更多
Coupling adsorption and in-situ Fenton-like oxidation process was developed for Methylene blue(MB) using refined iron-containing lowgrade attapulgite(ATP) clay, and the removal mechanism was investigated. The MB was i...Coupling adsorption and in-situ Fenton-like oxidation process was developed for Methylene blue(MB) using refined iron-containing lowgrade attapulgite(ATP) clay, and the removal mechanism was investigated. The MB was initially adsorbed on the porous ATPs, and then the enriched MB was removed by the H2O2-assisted Fenton-like oxidation with the iron-containing ATP catalyst. Under optimal conditions, the ATP powder exhibits the maximum removal efficiency of 100% with negligible iron leaching(1.5 mg L^(-1)) and no sludge formation. Furthermore,polysulfone/ATP(PSF/ATP) pellets were fabricated through a water-induced phase separation process to construct a fixed-bed reactor(FBR) for continuous contaminant removal. For the first cycle, the maximum adsorption capacity was 15.5 L with an outlet MB concentration of1.973 mg L-1(< 2 mg L^(-1), GB4287-2012) using the PSF/ATP pellets containing 50.0 g of ATP powders, and the maximum Fenton-like oxidation capacity was 35.5 L with the outlet concentration of 0.831 mg L^(-1). After five cycles, the total treated volume of the MB solution was ca. 255 L, and the efficiency remained above 99%. After 10 h of continuous treatment towards practical resin industrial wastewater, the chemical oxygen demand(COD) removal efficiency was still measured at 83.05%, costing 0.398 $ m^(-3). These results demonstrate the practical applicability of iron-containing low-grade ATP clay for textile water treatment.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
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
In the Republic of Benin,as in many other West African countries,urban areas have experienced rapid popula-tion growth in recent years.This situation has led to an increasing demand for sanitation facilities,necessita...In the Republic of Benin,as in many other West African countries,urban areas have experienced rapid popula-tion growth in recent years.This situation has led to an increasing demand for sanitation facilities,necessitating regular emptying of these systems.In a bid to reduce health risks and protect the surrounding natural environment,the manage-ment of the by-products from these systems has become a significant concern for decision-makers at various levels.This study aims to characterize fecal sludge at the Abomey-Calavi treatment station and suggest a mixed biological treatment approach.Fifteen sewage sludge samples were collected in 1,500 ml plastic bottles from Adjagbo’s Sewage Treatment Station,operated by SGDS-SA,a Waste Management and Sanitation company.Physico-chemical parameters were de-termined using spectrophotometric analysis.Colonies were enumerated using membrane filtration and inoculation.Cor-relation analysis was performed on sewage sludge samples.The main results indicate an alkaline character(pH>7)and a high organic pollutant load in the fecal sludge,with average concentrations of Chemical Oxygen Demand(COD)and Biochemical Oxygen Demand over 5 days(BOD_(5))at 18,730 mg O_(2).L^(-1)and 6,612 mg O_(2).L^(-1),respectively.The COD/BOD_(5) ratio of 2.83 suggests that the material is partially biodegradable.Furthermore,the nutrients exhibited high con-centrations of nitrates,with an average value of 4,786 mg.L^(-1),while nitrites,ammoniacal nitrogen,and orthophosphates had average concentrations of 22.48 mg.L^(-1),119.74 mg.L^(-1),and 239.0 mg.L^(-1),respectively.This study characterized fe-cal sludge at the Abomey-Calavi treatment station and suggests a mixed biological treatment approach.展开更多
This study focuses on the evaluation of the ammonia(NH_(3))stripping and the sizing of a sludge treatment plant,based on experimental results obtained at the station Sonfonia(Conakry,Guinea),based on the Heins-Coll mo...This study focuses on the evaluation of the ammonia(NH_(3))stripping and the sizing of a sludge treatment plant,based on experimental results obtained at the station Sonfonia(Conakry,Guinea),based on the Heins-Coll model.The targeted physicochemical parameters are temperature,the pH and nitrogenous forms NH_(3)/NH_(4)^(+).The nitrogen stripping process is described using the Azov and Goldman mathematical model,which allows for the estimation of the concentration of stripped ammonia nitrogen(N-NH_(3))as a function of temperature and pH.The methodology is based on sampling the liquid fraction at different levels of the station,followed by physicochemical analyses and a comparative interpretation of the results.The average results obtained for the period 2022-2023 at the plant inlet are as follows:temperature of 29.71℃,pH of 7.74,and NH_(3)concentration of 28.76 mg/L.These values show that the ammonia load of the incoming sludge is significantly lower than that considered in the initial design of the plant(142 mg/L).Monitoring the flow of the effluent through the four lagoons reveals a progressive decrease in concentrations,with average values of 29.66℃ and pH of 7.66.And NH_(3)of 16.91 mg/L,reflecting a significant purification performance of the lagoon system.Nitrogen stripping tests were conducted in 2023 at Lagoon 1,based on six observation points.The application of the Azov and Goldman model yielded the following results:temperature of 32.15℃,pH of 9.62,NH_(4)^(+)of 37.82 mg/L,NH_(3)of 29.83 mg/L,with an NH_(3)/NH_(4)^(+)ratio of 78.78%,confirming the determining influence of pH and temperature on the effectiveness of ammonia stripping.In conclusion,the analysis of the treatment performance of the Sonfonia sludge treatment plant highlights the relevance and robustness of the Azov and Goldman model,combined with the Heins-Coll model,for understanding nitrogen stripping mechanisms.The results obtained provide a reliable scientific basis for the optimization and design of new sludge treatment plants adapted to tropical climatic conditions.展开更多
The type and quantity of active sites on a catalyst surface determine catalytic activity.In this study,machine learning was employed to assist in the construction of C=O and pyridine N active sites using sludge waste....The type and quantity of active sites on a catalyst surface determine catalytic activity.In this study,machine learning was employed to assist in the construction of C=O and pyridine N active sites using sludge waste.Reactive descriptors,including C%,N%,O%,Fe%,pyrolysis temperature,heating rate,and pyrolysis time were proposed.Decision tree,extra tree,extreme gradient boosting(XGB),automatic relevance determination,and Bayesian ridge regression models were constructed and optimized.Among these,the XGB model was demonstrated with superior accuracy for prediction of C=O sites on the catalyst surface.Additionally,an ensemble model combining extra trees and XGB was developed to predict pyridine N,with R~2 value as high as 0.80 and minimum root mean square error(RMSE)of 0.1386.The ensemble model demonstrated a 17%improvement in accuracy compared to individual models.The model enables high-throughput screening of construction conditions for C=O and pyridine N.The study found that a pyrolysis temperature above of 500–800℃,a heating rate of 10–20℃/min,and a heating time of 120–200 min favor the generation of C=O active sites.For pyridine N sites,a pyrolysis temperature between 400℃ and 600℃,a heating rate of 5–10℃/min,and a pyrolysis time of around 150 min are optimal.Experimental validation demonstrated that both models exhibit excellent predictive performance,with prediction errors below 10%in all cases.This research provides a method to assist in the construction of C=O and pyridine N active sites,which is beneficial for guiding the design of sludge catalysts.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
基金the National Natural Science Foundation of China,grant number 52406074the China Postdoctoral Science Foundation under Grant Number 2025T180171+1 种基金the Natural Science Foundation of Guangdong Province(2025A1515011270)the China Southern Power Grid Technology Project(GDKJXM20231415/030100KC23120104).
文摘In order to explore the effects of CaO,lignite dust and sawdust on the drying characteristics ofmunicipal sludge at different concentrations,a three-factor three-level regression experiment was carried out based on the results of thermogravimetric experiment and single factor experiment.By fitting three common mathematical models,the Page model with the highest fitting degree was selected to determine the most suitable mathematical model to describe the municipal sludge drying process.In addition,the Box-Behnken design principle in the response surface method was used to analyze the interaction of three factors on the drying characteristics of municipal sludge.The results of the study show that below 100℃is the optimal drying temperature range for municipal sludge.The results of single factor experiments showed that the order of influence of the three factors on sludge drying time was CaO concentration>sawdust concentration>lignite dust concentration.In the single factor experiment,the optimal process parameterswere CaOconcentration 3%,lignite powder concentration 7%,and sawdust concentration 7%.In themulti-factor interaction analysis,the interaction between CaO and sawdust had the most significant effect on the reduction of drying time,and the order of influence was as follows:CaO interaction with sawdust>lignite dust interaction with sawdust>CaO interaction with lignite powder.Further analysis showed that the optimal process ratio was 3%CaO concentration and 3%sawdust concentration.
基金supported by the National Natural Science Foundation of China(No.22276219)the foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52121004)+1 种基金the major program Natural Science Foundation of Hunan Province of China(No.2021JC0001)the Fundamental Research Funds for the Central Universities of Central South University(No.2024ZZTS0063).
文摘Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the occurrence of Be in BCS is unclear,which seriously hinders the development of pollution control technologies.In order to enhance the understanding of BCS,the occurrence of Be and the microscale interactions with coexisting phases were investigated for the first time.It was found that CaSO_(4)·2H_(2)O and amorphous SiO_(2) are the primary phases of BCS.The simulated experiments of purified materials showed that Be interacted with CaSO_(4)·2H_(2)O and amorphous SiO_(2).Be can enter into the lattice of CaSO_(4)·2H_(2)O mainly as free Be2+.Amorphous SiO_(2) can adsorb Be2+particularly at a pH range of 3–5.The dissolution behavior experiment of BCS shows that about 52%of the Be is readily extracted under acidic conditions,which refers to the Be of independent occurrence.In contrast,the remaining 48%of Be can be extracted only after the CaSO_(4)·2H_(2)O has completely dissolved.Hence,CaSO_(4)·2H_(2)O is identified as the key occurrence phase which determines the highly efficient dissolution of Be.As a result,this study enhances the understanding of BCS and lays the foundation for the development of Be separation technologies.
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.
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.
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.
基金financially supported by the National Natural Science Foundation of China(Grant No.52078142).
文摘Leachate sludge,a byproduct of municipal solid waste leachate treated through biochemical processes,is characterized by high water content(761.1%)and significant organic matter content(71.2%).Cement that is commonly used for solidifying leachate sludge has shown limited effectiveness.To address this issue,an alkali-activated ground-granulated blast-furnace slag(GGBS)geopolymer blended with polypropylene fibers was developed to solidify leachate sludge.Moreover,unconfined compressive strength(UCS),immersion,as well as X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and scanning electron microscope(SEM)tests were conducted to investigate the solidification effect and mechanism of the GGBS-based geopolymer and fibers on leachate sludge.The results showed that:the 28-d UCS of the solidified sludge with 20%and 30%GGBS is 0.35 MPa and 1.85 MPa,and decreases to 0.18 MPa and 1.13 MPa,respectively,after soaked in water for 28 d.Notably,the UCS of the solidified sludge with 30%GGBS satisfied the strength requirement of roadbed materials.Polypropylene fibers significantly enhanced the strength,ductility and water stability of the solidified sludge,with an optimal fiber content of 0.3%.Alkali-activated GGBS geopolymer generated three-dimensional,cross-linked geopolymeric gels within the solidified sludge,cementing sludge particles and filling intergranular pores to form a stable cementitious structure,thereby achieving effective solidification.Furthermore,incorporating polypropylene fibers improved the bonding and anchoring effect between fiber and solidified sludge,constrained lateral deformation of the solidified sludge,restricted crack propagation,and enhanced engineering performance of the solidified leachate sludge.
基金Project supported by the National Natural Science Foundation of China(62175266,61775245)。
文摘The removal of harmful cyanobacterial blooms(HCBs)and reuse of the resulting algal sludge are pressing issues in current environmental governance and ecological conservation.Aiming at tackling the abovementioned challenges,titanium(Ti)-based coagulants are promising candidates.However,most of them suffer from poor stability and weak actual algal removal ability,and recycling of the algal sludge usually produces titanium dioxide(TiO_(2))with low photocatalytic ability.In this work,a lanthanum(La)-modified polytitanium chloride(La-PTC)coagulant is reported.La in the La-PTC coagulant serves a"kill two birds with one stone"strategy in algae removal and algae sludge reuse.Owing to the introduction of La ions,the La-PTC coagulant exhibits ultra-high stability and excellent algae removal capability with an efficiency of 98.71%,which is 7.25%higher than that of PTC coagulant.Moreover,recycling algae sludge can prepare high catalytic(2.45 times the commercial P25 TiO_(2))La/C-TiO_(2),where the presence of La enhances its visible light response range and inhibits electron hole recombination.The strategy of this La modified coagulant can not only achieve efficient re moval of HCBs,but also transfo rm the recovered algal sludge into photocatalysts with higher catalytic capacity.
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 the Scientific Research Start-up Project for the Introduction of Senior Talents of Chongqing Three Gorges Vocational College(sxzyzg-202405).
文摘The resource utilization of sludge can effectively achieve the regeneration and utilization of resources,and promote sustainable economic development.Sludge carbonization is a sludge treatment and disposal technology with broad application prospects,and its products have shown significant resource potential in land use,fuel utilization,and other fields.At present,China still faces some challenges in the resource utilization of sludge carbonization,such as issues related to heavy metal stability and outdated standards.In the future,it is necessary to further strengthen research,improve the standard system,and promote the widespread application of sludge carbonization technology,so as to achieve the goals of sludge reduction,harmlessness,and resource utilization and support the development of circular economy.
基金supported by Gansu Cuihua Technology Co.,Ltd.(H2020292)Science and Technology Planning of Baiyin City,Fundamental Research Funds for the Central Universities (buctrc202208)+2 种基金Engineering Research Center of Non-metallic Minerals of Zhejiang Province and the Beijing Engineering Center for Hierarchical Catalysts. Central Government Guiding Funds for Local Science and Technology Development (2022ZY015)Nanjiang Technology Project(2023AB028)Open Laboratory of State Key Laboratory of Organic and Inorganic Composites (oic-202301006)。
文摘Coupling adsorption and in-situ Fenton-like oxidation process was developed for Methylene blue(MB) using refined iron-containing lowgrade attapulgite(ATP) clay, and the removal mechanism was investigated. The MB was initially adsorbed on the porous ATPs, and then the enriched MB was removed by the H2O2-assisted Fenton-like oxidation with the iron-containing ATP catalyst. Under optimal conditions, the ATP powder exhibits the maximum removal efficiency of 100% with negligible iron leaching(1.5 mg L^(-1)) and no sludge formation. Furthermore,polysulfone/ATP(PSF/ATP) pellets were fabricated through a water-induced phase separation process to construct a fixed-bed reactor(FBR) for continuous contaminant removal. For the first cycle, the maximum adsorption capacity was 15.5 L with an outlet MB concentration of1.973 mg L-1(< 2 mg L^(-1), GB4287-2012) using the PSF/ATP pellets containing 50.0 g of ATP powders, and the maximum Fenton-like oxidation capacity was 35.5 L with the outlet concentration of 0.831 mg L^(-1). After five cycles, the total treated volume of the MB solution was ca. 255 L, and the efficiency remained above 99%. After 10 h of continuous treatment towards practical resin industrial wastewater, the chemical oxygen demand(COD) removal efficiency was still measured at 83.05%, costing 0.398 $ m^(-3). These results demonstrate the practical applicability of iron-containing low-grade ATP clay for textile water treatment.
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.
文摘In the Republic of Benin,as in many other West African countries,urban areas have experienced rapid popula-tion growth in recent years.This situation has led to an increasing demand for sanitation facilities,necessitating regular emptying of these systems.In a bid to reduce health risks and protect the surrounding natural environment,the manage-ment of the by-products from these systems has become a significant concern for decision-makers at various levels.This study aims to characterize fecal sludge at the Abomey-Calavi treatment station and suggest a mixed biological treatment approach.Fifteen sewage sludge samples were collected in 1,500 ml plastic bottles from Adjagbo’s Sewage Treatment Station,operated by SGDS-SA,a Waste Management and Sanitation company.Physico-chemical parameters were de-termined using spectrophotometric analysis.Colonies were enumerated using membrane filtration and inoculation.Cor-relation analysis was performed on sewage sludge samples.The main results indicate an alkaline character(pH>7)and a high organic pollutant load in the fecal sludge,with average concentrations of Chemical Oxygen Demand(COD)and Biochemical Oxygen Demand over 5 days(BOD_(5))at 18,730 mg O_(2).L^(-1)and 6,612 mg O_(2).L^(-1),respectively.The COD/BOD_(5) ratio of 2.83 suggests that the material is partially biodegradable.Furthermore,the nutrients exhibited high con-centrations of nitrates,with an average value of 4,786 mg.L^(-1),while nitrites,ammoniacal nitrogen,and orthophosphates had average concentrations of 22.48 mg.L^(-1),119.74 mg.L^(-1),and 239.0 mg.L^(-1),respectively.This study characterized fe-cal sludge at the Abomey-Calavi treatment station and suggests a mixed biological treatment approach.
文摘This study focuses on the evaluation of the ammonia(NH_(3))stripping and the sizing of a sludge treatment plant,based on experimental results obtained at the station Sonfonia(Conakry,Guinea),based on the Heins-Coll model.The targeted physicochemical parameters are temperature,the pH and nitrogenous forms NH_(3)/NH_(4)^(+).The nitrogen stripping process is described using the Azov and Goldman mathematical model,which allows for the estimation of the concentration of stripped ammonia nitrogen(N-NH_(3))as a function of temperature and pH.The methodology is based on sampling the liquid fraction at different levels of the station,followed by physicochemical analyses and a comparative interpretation of the results.The average results obtained for the period 2022-2023 at the plant inlet are as follows:temperature of 29.71℃,pH of 7.74,and NH_(3)concentration of 28.76 mg/L.These values show that the ammonia load of the incoming sludge is significantly lower than that considered in the initial design of the plant(142 mg/L).Monitoring the flow of the effluent through the four lagoons reveals a progressive decrease in concentrations,with average values of 29.66℃ and pH of 7.66.And NH_(3)of 16.91 mg/L,reflecting a significant purification performance of the lagoon system.Nitrogen stripping tests were conducted in 2023 at Lagoon 1,based on six observation points.The application of the Azov and Goldman model yielded the following results:temperature of 32.15℃,pH of 9.62,NH_(4)^(+)of 37.82 mg/L,NH_(3)of 29.83 mg/L,with an NH_(3)/NH_(4)^(+)ratio of 78.78%,confirming the determining influence of pH and temperature on the effectiveness of ammonia stripping.In conclusion,the analysis of the treatment performance of the Sonfonia sludge treatment plant highlights the relevance and robustness of the Azov and Goldman model,combined with the Heins-Coll model,for understanding nitrogen stripping mechanisms.The results obtained provide a reliable scientific basis for the optimization and design of new sludge treatment plants adapted to tropical climatic conditions.
基金supported by the Young Scientific and Technological Talents(Level Two)in Tianjin(No.QN20230214)Climbing Program of Tianjin University(No.2023XPD-0006)+1 种基金National Natural Science Foundation of China(No.52100156)National Engineering Research Center for Digital Construction and Evaluation Technology of Urban Rail Transit(No.2023HJ02)for the financial support。
文摘The type and quantity of active sites on a catalyst surface determine catalytic activity.In this study,machine learning was employed to assist in the construction of C=O and pyridine N active sites using sludge waste.Reactive descriptors,including C%,N%,O%,Fe%,pyrolysis temperature,heating rate,and pyrolysis time were proposed.Decision tree,extra tree,extreme gradient boosting(XGB),automatic relevance determination,and Bayesian ridge regression models were constructed and optimized.Among these,the XGB model was demonstrated with superior accuracy for prediction of C=O sites on the catalyst surface.Additionally,an ensemble model combining extra trees and XGB was developed to predict pyridine N,with R~2 value as high as 0.80 and minimum root mean square error(RMSE)of 0.1386.The ensemble model demonstrated a 17%improvement in accuracy compared to individual models.The model enables high-throughput screening of construction conditions for C=O and pyridine N.The study found that a pyrolysis temperature above of 500–800℃,a heating rate of 10–20℃/min,and a heating time of 120–200 min favor the generation of C=O active sites.For pyridine N sites,a pyrolysis temperature between 400℃ and 600℃,a heating rate of 5–10℃/min,and a pyrolysis time of around 150 min are optimal.Experimental validation demonstrated that both models exhibit excellent predictive performance,with prediction errors below 10%in all cases.This research provides a method to assist in the construction of C=O and pyridine N active sites,which is beneficial for guiding the design of sludge catalysts.
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.
