Solid-liquid Separation Research Articles

Phosphonate functionalized magnetic mesoporous silica for rare earth element recovery from citrate assisted solid waste extracts

The growing high demand of rare earth elements (REEs) has prompted extensive research on REE recovery from waste streams. This study reports the synthesis and evaluation of phosphonate-functionalized magnetic mesoporous silica (MMS-PP) for REE recovery from the acidic extracts of solid wastes. MMS-PP was synthesized using surfactant template and post-synthesis methods, and tested using simulated and real extraction solutions from citrate-assisted REE extracts from municipal solid waste incineration (MSWI) ash. The organic-inorganic hybrid MMS-PP was evaluated for La recovery from 50 mM simulated citrate extract, with the adsorption capacity of 13.5 mg/g compared to ∼2.5 mg/g for non-functionalized MMS. The MMS-PP material exhibited fast adsorption within 10 min, good La selectivity against competing Na+ and Ca2+, moderate selectivity against Al3+ and Fe3+, high recyclability over multiple adsorption-desorption cycles, and equivalent efficiency for La, Ce, Nd, and Y recovery. The MMS-PP material also demonstrated 70–95% REE recovery from real citrate extracts of MSWI ash, and the spent MMS-PP material can be regenerated and reused for multiple cycles. Functionalized mesoporous materials in combination with organic-ligand assisted extraction can potentially provide a green, effective, and tunable solid-liquid separation platform for REE recovery from complex solid waste streams.

Analysis of microbial communities in solid and liquid pig manure during the fertilization process

Utilizing livestock manure as organic fertilizer in sustainable agriculture is crucial and should be developed through an appropriate manufacturing process. Solid–liquid separation contributes to reducing odor, managing nutrients in livestock excretions, and lowering the cost of transporting manure to arable soil. To investigate the impact of fermentation after solid–liquid separation, we examined the specific correlation between chemical properties and bacterial communities in solid–liquid manures before and after the fermentation process. In terms of chemical properties before fermentation, the levels of electrical conductivity, nitrogen, ammonium nitrogen (NH4+-N), potassium, sodium, and chloride were higher in the liquid sample than in the solid sample. However, the chemical components of the liquid sample decreased during fermentation, which could be attributed to the low organic matter content. Many chemical components increased in the solid samples during fermentation. Fifty-six bacterial species were significantly correlated with NH4+-N and phosphorus. Following fermentation, their abundance increased in the solid samples and decreased in the liquid samples, indicating the potential for NH4+-N release or phosphorus mineralization from organic matter. These results provide information regarding changes in nutrient and bacterial formation when applying the fermentation process after solid–liquid separation.

The characteristics and flocculation performance of hydrophobic association poly‐(3‐methacryloylamido propyl trimethyl ammonium chloride)

AbstractThe cationic polymer plays a crucial role in the flocculation process for solid–liquid separation. A hydrophobic‐associated cationic polymer was prepared through micellar free‐radical polymerization of cationic monomer 3‐methyl acrylamide propyl trimethyl ammonium chloride (MAPTAC) and hydrophobic monomer Poly (ethylene glycol) Octadecyl methacrylate (OEMA). The Poly‐MAPTAC‐OEMA can form network structure through intermolecular hydrophobic association in aqueous solution, which leads to the solution viscosity increase and the salt thickening property. The critical associating concentrations (CACs) of Poly‐MAPTAC‐OEMA are 5818–6992 mg/L in aqueous solution. For the diatomite suspensions, at the dosage above about 5 mg/L, the Poly‐MAPTAC‐OEMA can show higher flocculation efficiency compared with Poly‐MAPTAC. Specifically, at the dosage of 8 mg/L, the enhancement rate of sedimentation rate can reach 7.27%–32.31%. Meanwhile, the hydrophobic association mainly enhances the bridging ability but has no significant effect on the improvement of the electric neutralization ability of Poly‐MAPTAC‐OEMA. The flocculation performance‐enhanced dosage of Poly‐MAPTAC‐OEMA is obviously lower than the CAC of Poly‐MAPTAC‐OEMA; this may be because during the flocculation process, the Poly‐MAPTAC‐OEMA first absorb and deeply concentrate on the particle surface, and then the hydrophobic association and bridging enhancement of Poly‐MAPTAC‐OEMA can occur more easily on the particle surface.

Solid-liquid phase separation diffused Nd-Fe-B sintered magnets by using DyH3 nanopowder realize high-efficiency coercivity improvement and overcome thickness limit

In this study, new grain boundary diffusion (GBD) technology is applied to Nd-Fe-B sintered magnets with different thicknesses utilizing DyH3 nanopowder. The weight ratio is 0.25 wt.%. For comparison, the GBD processes include solid-liquid phase separation diffusion (SepD) and solid-liquid phase simultaneous diffusion (SimD). The magnetic properties and microstructure of GBD magnets with different thicknesses are thoroughly investigated. The comprehensive magnetic properties of SepD magnets are higher than SimD magnets. When the magnets are 8 mm thick, the SepD magnet obtains a coercivity of 18.10 kOe, which is higher than the SimD magnets (17.00 kOe). It was determined that SepD can manufacture thick magnets with excellent coercivity. In SepD magnets, the Dy element diffusion distance is deeper than in SimD magnets. For SepD magnets, there are core-shell structures formed in the surface region, while there are anti-core-shell structures that are unfavorable to magnetic properties in the surface region of the SimD magnets. The enhanced coercivity and temperature stability of the SepD magnets is primarily due to the more continuous core-shell structures produced by the deeper diffusion depth of the Dy element. This study will provide more theoretical guidance for the application of SepD in magnets with different thicknesses.

Surface charge density and induced currents by self-charging sliding drops.

Spontaneous charge separation in drops sliding over a hydrophobized insulator surface is a well-known phenomenon and lots of efforts have been made to utilize this effect for energy harvesting. For maximizing the efficiency of such devices, a comprehensive understanding of the dewetted surface charge would be required to quantitatively predict the electric current signals, in particular for drop sequences. Here, we use a method based on mirror charge detection to locally measure the surface charge density after drops move over a hydrophobic surface. For this purpose, we position a metal electrode beneath the hydrophobic substrate to measure the capacitive current induced by the moving drop. Furthermore, we investigate drop-induced charging on different dielectric surfaces together with the surface neutralization processes. The surface neutralizes over a characteristic time, which is influenced by the substrate and the surrounding environment. We present an analytical model that describes the slide electrification using measurable parameters such as the surface charge density and its neutralization time. Understanding the model parameters and refining them will enable a targeted optimization of the efficiency in solid-liquid charge separation.

Solid–liquid separation of lignocellulosic sugars from biomass by rotating ceramic disc filtration

A simple, low energy, and productive filtration method to clarify biomass hydrolysate to enable biochemical and thermochemical pathways to biofuels and biochemicals.

Membrane fouling and control in algae-rich water treatment

Microfiltration and ultrafiltration membrane technology has now become one of the important methods for algae-rich water treatment due to its better solid-liquid separation effect and microbial retention capacity, while the existence of membrane fouling has been restricting the full-scale promotion and application of low-pressure membrane technology. The main foulants causing membrane fouling in algal-rich water include algal cells, algal debris and algal organic matter AOM (EOM and IOM). In this paper, the mechanism of membrane fouling caused by algal foulants in MF/UF for high algal water treatment is analysed in terms of both individual and composite fouling. Both individual and composite effects of algal foulants can lead to severe membrane fouling, in which algal cells and algal debris mainly dominate the accumulation of filter cake, while AOM mainly leads to membrane pore blockage membrane fouling is exacerbated by compounding effects, with severe reversible and irreversible fouling caused by filter cake formation and membrane pore shrinkage. This paper also discusses several common membrane fouling control methods, including pretreatment (oxidation, coagulation, combined oxidation-coagulation and adsorption) and membrane modification, and it is found that these several membrane fouling control methods can achieve good results.

牛粪压缩和应力松弛特性及其本构模型构建研究

In order to study the mechanical properties of compression and stress relaxation of manure under drainage conditions, the experiment was carried out with cattle manure as the object, and the constitutive models were improved to describe the stress-strain curves of compression and stress relaxation. The defined constitutive model was determined by parameter identification, and the influence laws of moisture content and filling mass on the compression and relaxation process were investigated. The results show that the improved Nishihara model and the five-component generalized Maxwell model can better describe the compression and stress relaxation properties of cattle manure, and the coefficients of determination of the parameters of the fitted intrinsic model are all greater than 0.9, with high fitting accuracy. The compression process was divided into three stages: exhaust, drainage, and viscoelastic-plastic deformation. The stress decay rate tended to change quickly and then slowly, and there was a negative correlation between the compressed mass, moisture content, and stress decay rate. Duncan's mean comparisons revealed that the differences in elastic modulus between different moisture content / compressed mass groups in the parameters of the cattle manure compression principal model were all significant (P<0.05). The differences in elastic modulus and coefficient of viscous attenuation between different moisture content groups in the parameters of the stress relaxation model were all significant. The study's results can provide the theoretical basis for the study and simulation of CM's compression and dewatering mechanism and provide support for the solid-liquid separator for livestock and poultry manure.

Morphology control of waste polyesters for enhanced glycolysis reactivity and minimization of side reactions

Effective pretreatment routes using dimethyl sulfoxide (DMSO) as solvent were accomplished to enhance the polyethylene terephthalate (PET) glycolysis rate. Highly ordered structure PET flakes were dissolved in DMSO at high temperatures, followed by solid–liquid separation using two different methods to generate micro-sized powders. Under identical glycolysis conditions, the reaction time of pretreated PET powders was gradually reduced by approximately five times that of PET flakes. During the glycolysis of PET with ethylene glycol (EG), diethylene glycol-containing terephthalate compounds (DCTC) are formed as undesired byproducts at high temperatures. These byproducts significantly affect the overall quality of BHET. Consequently, pretreated PET degradation under mild conditions was employed as a preventive measure against EG dehydration, leading to the production of DCTC. PET powders with controlled morphology exhibit outstanding performance and achieve a 100 % PET conversion at 180 °C to DCTC-free bis(2-hydroxyethyl) terephthalate (BHET). The purity of the obtained BHET was characterized using proton–NMR spectroscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry. The utilization of this technology presents a potential solution for overcoming the technical and economic challenges associated with current PET upcycling methodologies.

Dynamic membrane filtration accelerates electroactive biofilms in bioelectrochemical systems

Bioelectrochemical systems (BES) have emerged as a dual-function technology for treating wastewater and recovering energy. A vital element of BES is the rapid formation and maintenance of electroactive biofilms (EABs). Previous attempts to accelerate EAB formation and improve electroactivities focused on enhancing the bacterial adhesion process while neglecting the rate-limiting step of the bacterial transport process. Here, we introduce membrane filtration into BES, establishing a dynamic membrane filtration system that enhances overall performance. We observed that optimal membrane flux considerably reduced the startup time for EAB formation. Specifically, EABs established under a 25 L m−2 h−1 flux (EAB25 LMH) had a formation time of 43.8 ± 1.3 h, notably faster than the 51.4 ± 1.6 h in the static state (EAB0 LMH). Additionally, EAB25 LMH exhibited a significant increase in maximum current density, approximately 2.2 times higher than EAB0 LMH. Pearson correlation analysis indicated a positive relationship between current densities and biomass quantities and an inverse correlation with startup time. Microbial analysis revealed two critical findings: (i) variations in maximum current densities across different filtration conditions were associated with redox-active substances and biomass accumulation, and (ii) the incorporation of a filtration process in EAB formation enhanced the proportion of viable cells and encouraged a more diverse range of electroactive bacteria. Moreover, the novel electroactive membrane demonstrated sustained current production and effective solid-liquid separation during prolonged operation, indicating its potential as a viable alternative in membrane-based systems. This approach not only provides a new operational model for BES but also holds promise for expanding its application in future wastewater treatment solutions.

Facile synthesis of robust polyethyleneimine incorporated chitosan composite hydrogel for efficient enrichment of uranium(VI) in aqueous solution

The development of polymer hydrogel with abundant ion diffusion paths is needed to address sustainable energy supply and ecological security. Herein, a robust chitosan-based polymer hydrogel with superior structural stability and sufficient active sites was fabricated by incorporating polyethyleneimine into chitosan for efficient enrichment of uranium(VI). The as-prepared chitosan-based polymer hydrogel has a maximum uranium adsorption capacity of 291.75 mg-U/g at pH= 6, together with relatively good selectivity to uranium(VI). The adsorption process was described well with the pseudo-second-order kinetic model and Langmuir isotherm model. The main adsorption mechanism was related to the complexation of uranyl ions with the amino and hydroxyl groups. The chitosan-based polymer hydrogel, with the merits of facile preparation, easy solid-liquid separation, eco-friendliness and cyclic utilization highlights its promising application in uranium removal and recovery from uranium-containing wastewater.

Removing copper ion from wastewater by surface precipitation using novel hierarchical hydrated magnesium carbonate crystal

It is significant to develop a low-cost, easy-to-separate and efficient adsorbent to remove heavy metals from wastewater. Therefore, the hierarchical hydrated magnesium carbonate (HMC) crystal is prepared. The performances of HMC crystal at different adsorption conditions are studied. The surfaces of HMC crystal before and after Cu2+ adsorption are characterized by XRD, FTIR, XPS, SEM and EDS mapping. The removal efficiency of Cu2+ reaches 99 % under the conditions of an initial concentration of 300 mg/L, HMC dosage of 0.5 g/L, pH value of 4.5 and adsorption time of 180 min. The adsorption kinetic and isotherm can be described by the pseudo-second-order model and Langmuir adsorption model, respectively. The maximum adsorption capacity of Cu2+ is 1406 mg/g. The hierarchical structure provides HMC crystal with sufficient hydroxide ions for Cu2+ surface precipitation and large particle size (40–100 μm) for subsequent solid–liquid separation, presenting a promising application prospect in the future.

Adsorption of polyacrylamides on mineral oxides: Effect of solution pH and polymer molecular weight

Acrylamide-based polymers such as polyacrylamide (PAM) and their derivatives are widely used as additives to enhance solid-liquid separation in the mineral processing industry. Thus, an investigation of polyacrylamide behaviour at oxide-aqueous solution interfaces is of vital importance. In this work, the adsorption of different molecular weight polyacrylamides onto iron oxides and silica was quantified at different pH values. Mineral oxides were characterised by zeta potential, particle size distribution, scanning electron microscopy images and X-ray diffraction. The Sauter mean D[3,2] diameter of the hematite, magnetite and silica were measured to be 0.8, 1.9, and 2.0 µm respectively. An anionic polyacrylamide (PAM A, MW 520 kg/mol) exhibited strong variation in adsorbed amount with pH, while the adsorption of two neutral polyacrylamides (PAM N, MW 40 & 5500 kg/mol) had a weak dependence on pH. All three polyacrylamides had similar adsorption capacity on the iron oxides particles, thus minimal influence of molecular weight was observed. The adsorption isotherms were fit to the Langmuir model to facilitate interpretation of the adsorption mechanism. The highest adsorption plateau density of 11.4 mg/m2 on magnetite and 7.4 mg/m2 on hematite for PAM A was found to be at lower pH. At the same pH, high molecular weight PAM N shows the highest adsorption plateau density of 7.8 mg/m2 and at unadjusted pH, low molecular weight PAM N adsorbs to 5.2 mg/m2 on magnetite. All PAM samples selectively adsorb on the iron oxide particles compared to silica particles. These quantified adsorbed amounts are concordant with the current use of high molecular weight PAM as an effective flocculant.

Resolved Simulation of the Clarification and Dewatering in Decanter Centrifuges

Solid–liquid separation is a fundamental operation in process engineering and thus an important part of many process chains in the preparation of slurries in the chemical industry and other parts of the industrial environment. For the separation of micron-sized particles which, due to their size, do not settle or settle very slowly in the earth’s gravity field, centrifuges are often used. The preferred choice are often decanter centrifuges because they work continuously and stabilize the process against product fluctuations due to their adjustment possibilities. The design of the apparatus is complex: The main components of the apparatus are the cylindrical-conical bowl, which rotates at a high speed, and a screw located inside the bowl, which rotates in the same direction at a low differential speed to transport the separated solids out of the apparatus. Geometrical properties of the apparatus, as well as the adjustable operating parameters, such as rotational speed or differential speed, have a significant influence on the separation. In practice, analytical models and the experience of the manufacturers form the basis for the design. Characteristics of the disperse phase, interactions with the liquid, as well as the influence of the flow on the separation, are not taken into account. As a consequence, the transfer to industrial scale always requires a large number of pilot-scale experiments, which are time-consuming and expensive. Due to the increasing computational power, computational fluid dynamics (CFD) provides one possibility to minimize the experimental effort in centrifuge design. In this work, the open-source software OpenFOAM is used to simulate the multi-phase flow in a laboratory decanter centrifuge. For validation, experiments were carried out on a laboratory scale and the main operating parameters, such as speed, differential speed, and volume flow rate, were varied. The simulation results show a good agreement with the experimental data. Furthermore, the numerical investigations show the influence of the flow on the separation of the particles. To evaluate the transportability of a material, the transport efficiency was introduced as a dimensionless parameter. In addition, the simulation allows the consideration of the individual velocity components, making it possible to generate an impression of the complex three-dimensional flow in the apparatus for the first time.

Solid–Liquid Separation and Its Environmental Impact on Manure Treatment in Scaled Pig Farms—Evidence Based on Life Cycle Assessment

Recently, there has been a significant focus on the issue of pollution caused by livestock and poultry rearing, which is recognized as a prominent contributor to nonpoint source pollution in the agricultural sector. This study employed the life cycle assessment (LCA) methodology to evaluate the environmental impact of several pig manure processing scenarios with the aim of determining the appropriate solid–liquid separation tool for large-scale pig farms. The findings indicate that the utilization of a screw extruder for solid–liquid separation in Scenario 2 has a lower environmental impact. In contrast to Scenario 1, Scenario 2 exhibits reduced environmental potential in the areas of global warming, human toxicity, acidification, and eutrophication. Specifically, the global warming, human toxicity, acidification, and eutrophication impacts decreased by 56%, 81%, 83%, and 273%, respectively, due to the implementation of solid–liquid separation. The type of solid–liquid separation equipment used during the processing of swine manure, as well as the subsequent treatment, have a significant impact on environmental emissions. Compared to Scenario 2, Scenario 3, which utilizes a centrifugal microfilter for solid–liquid separation, exhibits a lower environmental impact in terms of human toxicity, resulting in a reduction of 0.736 kg DCB-eq. In general, solid–liquid separation is a viable and environmentally friendly method for the disposal of waste from large-scale pig farms. The adoption of this method is highly recommended. During its implementation, careful consideration should be given to factors such as separation efficiency and pollution emissions. It is crucial to select appropriate equipment for solid–liquid separation to effectively process the waste.

Innovative cation exchange-driven carbon migration and recovery patterns in anaerobic fermentation of waste activated sludge

Despite numerous treatments have been developed to enhance anaerobic fermentation of waste activated sludge, the innovative cation exchange (CE) approach has been rarely reported, little attempt was conducted to revealcarbon source fate. The interphase carbon balance was illustrated to clarify endogenous carbon dissolution, biotransformation,and recovery patterns. By CE-mediated divalent cation removal, almost 34.72 % of particulate carbon sources were dissolved in 2-day treatment, corresponding to soluble carbon content of 1165.58 mg C/L. Most of the originally dissolved carbon sources (58.01–66.81 %) were bio-transformed to volatile fatty acids with high bioavailability, while the further transformation to biogas was inhibited, contributing to recoverable carbon source accumulation. Overall, 21.38 % of total solid carbon sources were recovered through 8-day fermentation, the carbon extraction was implemented by solid–liquid separation with carbon loss of 14.21–22.91 %, manifesting the valid carbon recovery of 85.05–87.96 mg C/g VSS. Such CE-driven carbon recovery provided negentropy benefits in sustainable cycle economy.

Fast and efficient capture of iodide ions by silver-modified GO nanosheets: From adsorption to membrane filtration

The treatment of radioactive contaminated water is highly valued all over the world nowadays. In this article, an easy-operated strategy with clear principle for the efficient purification of radioactive iodide wastewater was proposed. Silver nanoparticles (Ag NPs) were grown in-situ at the oxygen-containing defect sites on the edge of GO nanosheets, and the nanocomposites were tested for both adsorption and membrane filtration. HRTEM and XRD results confirmed the crystalline structure of Ag and AgI before and after the adsorption. Fast adsorption equilibrium of iodides was observed within 15 min, and theoretical maximum equilibrium capacity was calculated as high as 150.17 mg g−1. Dead-end filtration performances of this Ag-GO stacked membranes were further studied from the view of avoiding secondary radionuclides pollution caused by the difficult recovery of nano powders. The rejection ratio of iodides kept constant which was higher than 90 % during the first thirty minutes. AgI precipitation adsorption and size sieving of confined GO interlayers by the stacked Ag-GO membranes happened simultaneously. Suitable concentration of NaOH can wash out most of the iodide ions entrapped between the confined GO interlayers, and desorb part of the AgI meanwhile. All these results elucidated the application of these Ag-GO NPs for the fast and efficient adsorption of iodides are the most prominent advantage, and the adsorbents exhibited desired adsorption irreversibility. Ag-GO filtration membranes could help these nano powders get an easy solid–liquid separation step.

Ultra-High-Molecular-Weight, Narrow-Polydispersity Polyacrylamides Synthesized Using Photoiniferter Polymerization to Generate High-Performance Flocculants.

Ultra-high-molecular-weight, water-soluble polyelectrolytes are commonly employed as flocculants for solid-liquid separation via colloidal destabilization, enabling the rapid and efficient removal of particulate matter from wastewater streams. A drive toward more sustainable and less polluting industrial practices, coupled with the desire to reduce freshwater usage and improve closed-loop systems, demands the development of flocculants with ever-higher dewatering dose performance. Herein, the use of trithiocarbonate-mediated reversible addition-fragmentation chain transfer (RAFT) polymerization under either blue LED (λmax = 470 nm) or UV (λmax = 365 nm) irradiation, known as photoiniferter polymerization, was successfully utilized to generate ultra-high-molecular-weight (Mn > 1,000,000 g mol-1) polyelectrolyte copolymer flocculants with narrow molecular weight distributions (Mw/Mn < 1.2). Cationic and anionic polyelectrolyte flocculants were synthesized containing various monomer compositions of acrylamide (AM), dimethylacrylamide (DMA), 3-(acryloyloxyethyll)trimethylammonium chloride (DMAEAq), 3-(acrylamidopropyl)trimethylammonium chloride (APTAC), sodium acrylate (NaAA), and sodium 2-(acrylamido)-2-methylpropylsulfonate (NaATBS) with high monomer conversion using simple experimental apparatus. The narrow molecular weight distribution cationic polyelectrolytes showed improved flocculation efficiency in the clarification of kaolin suspensions of up to 50% in comparison to a broad polydispersity (Mw/Mn > 5.0) commercial benchmark with an equivalent number average molecular weight. The improved performance of the narrow-polydispersity copolymers is attributed to the reduction in the content of the lower-molecular-weight polymer chains, which impart lower flocculation performance.

Influence of three different manure treatments on antimicrobial resistance genes and mobile genetic elements

There is a growing concern about the potential dissemination of antimicrobial resistance into agricultural fields due to the application of manure as crop fertilizer. While reducing the usage of antibiotics in livestock production stands as the first alternative to prevent this problem, there is evidence that this may not be enough to eliminate antimicrobial resistance elements already present in manure microbiomes. This study employed a metagenomic approach to investigate the impact of common manure treatments, including aerobic storage, mesophilic anaerobic digestion (MAD), and solid-liquid separation, on the presence and abundance of antimicrobial resistance genes (ARGs), bactericides, and heavy metal resistance genes (BacMet), and mobile genetic elements (MGEs) in manure from three different farms, including one operating in an antibiotic-free environment. The results indicated that MAD was the best method to reduce the numbers of ARGs, BacMet, and MGEs, achieving reduction rates greater than 40%, 89%, and 68%, respectively. Manure storage significantly reduced BacMet levels (over 30%) and MGEs (28%) but had no significant effect on total ARG levels. Solids recovered through solid-liquid separation exhibited elevated levels of ARGs, BacMet, and MGEs, while the liquid fraction displayed levels similar to untreated manures. Correlation and co-occurrence modeling analyses indicated that changes in microbial communities, particularly fluctuations in aerobic and facultative communities belonging to Bacillota, Actinomycetota, and Pseudomonadota phyla, played a significant role in driving changes in ARGs, BacMet, and MGEs. The results also showed the presence of toxin-antitoxin and transposon systems near different ARGs. Overall, the results confirmed that genes conferring resistance to various antimicrobials and MGE capable of mobilizing them are widely spread in dairy farms; that even under the absence of antibiotics, the use of heavy metals and disinfectants may promote the maintenance of ARGs and MGEs, and; that treatment such as anaerobic digestion could reduce the risk of the spread of antimicrobial resistance.

Insights into the kinetics, thermodynamics and evolved gases for the pyrolysis of freshly excreted and solid-liquid separated swine manures

Swine manure (SM) is one of the dominant livestock wastes in China. Pyrolysis is increasingly needed in valorizing SM into diverse products. However, little is known about the pyrolysis characteristics for SM. The results showed that the common-used solid-liquid separation in the SM management chain changed its physicochemical properties and pyrolysis characteristics. Specifically, the average activation energies (Ea) calculated by Flynn-Wall-Ozawa, Kissenger-Akahira-Sunose and Starink models for SM collected in pigsty (SM-A) were 184.70, 181.34 and 181.73 kJ/mol (R2 > 0.9) at conversion rate (a) = 0.2–0.7, respectively, which were increased by > 30 kJ/mol for solid-liquid separated SM (SM-B). Top pre-exponential values (A) for SM-A were also lower than these for SM-B. The ΔG and ΔS were decreased with the progressing of SM-A pyrolysis, while these for SM-B pyrolysis showed increases. Furthermore, SM-A pyrolysis produced more gas species than SM-B, which was more reactive during pyrolysis. Finally, this study suggested that although SM could be a potential energy source through the conversion by pyrolysis, attention should be paid on the impacts of manure management chain on SM pyrolysis.