Solid-liquid Separation Research Articles

A Critical Review on Water Overconsumption in Lignocellulosic Biomass Pretreatment for Ethanol Production through Enzymic Hydrolysis and Fermentation

Global demand for renewable and sustainable energy fostered the considerable development of biomass-to-ethanol valorization strategies. Thermochemical pretreatment methods have been proposed to render biomass more amenable to enzymatic and microbial digestion. However, the efforts have not led to its industrial-scale worldwide realization. One of the obstacles to commercialization could be related to water overconsumption, as excessive water washing of the pretreated slurry is often performed to remove inhibitory compounds and residual chemicals after biomass pretreatment. Only increasing solid loading for biomass pretreatment results in ineffective pretreatment performance, more inhibitors formation, and high viscosity, which in turn necessitates the water washing step. A number of physicochemical and biological methods are applied to detoxify the acid-pretreated liquid fraction for enzymatic hydrolysis and fermentation. Among them, alkaline neutralization and liquid–liquid extraction are preferred because of their simple operation and low cost. Seemingly, recycling black liquor for alkali pretreatment offers a pathway to reduce water and chemical consumption, but alkali replenishment and inhibitor accumulation significantly weaken this technology. Interestingly, quite a few studies have removed the water washing and even solid–liquid separation steps after (liquid hot water, Tween 40, and CaO) pretreatment. There is still much room for future studies to render biomass pretreatment more feasible in terms of economic and environmental points of view. This review provides a deep understanding of wastewater generation during biomass upgrading and discusses the solutions to reduce water consumption critically.

New grain boundary diffusion strategy of Nd-Fe-B sintered magnets to achieve breakthroughs in Tb-availability and thick limitation

Grain boundary diffusion (GBD) Nd-Fe-B sintered magnets were prepared using a newly developed solid-liquid phase separation diffusion (SepD) technique, as well as a currently popular solid-liquid phase simultaneous diffusion (SimD) technique. The magnetic properties, microstructures, and magnetic domain morphologies of the magnets with different Tb contents diffused using the two techniques were then investigated. A SepD magnet using 0.25 wt% Tb exhibited a similar coercivity and a stronger maximum energy product compared to a SimD magnet with 0.50 wt% Tb, demonstrating high Tb availability. Moreover, by using the new diffusion technique, Tb could diffuse deeper into the magnet and distribute more homogeneously around the surface region of the Nd2Fe14B crystal grains, forming the crucial core-shell structure without undesirable enrichment in the surface area of the magnet. As a result, the squareness factor increased noticeably from 0.842 for the current technique diffused magnet to 0.925 for the new technique diffused magnet with a thickness of 8 mm.

Potentiality of Rod-Type Chitosan Adsorbent Derived from Sewage Sludge

The potential use of wastewater sludge as a biosorbent for the removal of various metals and metalloids from aqueous solutions was investigated. The sludge was immobilized in a rod shape with chitosan to improve sorption capacity and solid–liquid separation ability. An optimal condition for the production of rod-shaped chitosan-immobilized sludge (RCS) was determined by considering the biosorbent production potential and As(V) removal efficiency. The optimal sludge and chitosan contents and RCS thickness were 6.0%, 4.0%, and 0.2–0.3 mm, respectively. The anion removal performance of RCS was investigated for As(V), Cr(VI), and Mn(VII), and the cation removal performance was investigated for Cd(II). Pseudo-first-order and pseudo-second-order models adequately explained the kinetic data for the RCS, while the Langmuir and Freundlich models explained the equilibrium data for the RCS. These results showed that RCS has a higher adsorption capacity for anions than for cations. The results also indicated that electrostatic attraction or ion exchange is the main mechanism for metal/metalloid removal by RCS, except for the case of Mn(VII) where an adsorption-coupled reduction mechanism may be suggested.

One-step preparation of coal-based magnetic activated carbon with hierarchically porous structure and easy magnetic separation capability for adsorption applications

Coal-based magnetic activated carbons (CMACs) were prepared from Zhundong coal in the presence of various Fe-based additives by fast one-step physical activation method. The roles of types and doses of Fe sources for pore structures and magnetic properties of the resulting CMACs were systematically investigated. Fe species in coal promoted the development of mesopore structures, and AC-FC-3 derived from FeCl3-loaded coal (3% Fe content) possessed hierarchical pore structure with highest micropore and mesopore volumes up to 0.282 cm3·g−1 and 0.222 cm3·g−1, respectively. Considering the minimum dose of additives, the CMACs loaded a trace amount of reduced iron powder (0.5% and 1% weight ratios of coal) were prepared, and had improved micropore and mesopore structures compared with AC derived from the demineralized coal. Meanwhile, strong magnetic iron oxides (Fe3O4 and γ-Fe2O3) were generated during CO2 activation process. The CMACs derived from different Fe sources loaded coal samples with same Fe content (3% weight ratio of coal) had saturation magnetizations of 0.55–14.26 emu·g−1. Evaluated as adsorbents for Methylene Blue (MB) removal, the CMACs with hierarchical pore structure exhibited better MB adsorption capacities up to 120.3 mg·g−1. Furthermore, the magnetic properties of CMAC could accelerate the solid–liquid separation with an applied magnetic field and improve recovery efficiency of the adsorbent.

The effects of grass biomass preservation methods, organic acid treatment and press type on the separation efficiency in the green biorefinery

Processing green biomass into novel products provides opportunities to improve the sustainability of the bioeconomy. The objective of this study was to evaluate the effects of biomass types (fresh, frozen-and-thawed, dried-and-rehydrated and ensiled grass) as well as formic and propionic acid-based additive on the efficiency of liquid-solid separation and crude protein (CP) yield. Three different pressing methods for liquid-solid separation were used. All preservation methods improved biorefinery efficiency compared to fresh grass, and the effect of additive was more profound on the fresh biomass than other materials. However, due to lower CP concentration in the liquid, presumably caused by lower nitrogen solubility, the amount of CP retained in the liquid was not improved in response to the additive treatment. The type of processing technology plays a key role in the extraction of relevant compounds from biomass. With less efficient separation methods, the effects of pretreatments were more pronounced.

Polyethyleneimine/polydopamine-functionalized self-floating microspheres for caramel adsorption: Interactions and phenomenological mass transfer kinetics

A polyethyleneimine/polydopamine-functionalized self-floating microsphere (EHGM/PDA/PEI) bears an etched hollow glass microsphere as a support, polydopamine as an interfacial cross-linking “glue”, and polyethyleneimine as a functional monomer was fabricated and used as a decolorization sorbent for sugarcane juice. The advantages of EHGM/PDA/PEI for sugarcane juice decolorization were attributed to its richness of target polyethyleneimine monomers, well-connected and abundant three-dimensional network-like aperture structure, and nontoxicity. Moreover, EHGM/PDA/PEI has excellent self-floating performance to allow separation from the adsorption system after decolorization and may have a faster separation speed and lower energy consumption than conventional solid–liquid separation methods. Synthetic caramels were used as model colorants of sugarcane juice to assess EHGM/PDA/PEI performance. The adsorption capacity of EHGM/PDA/PEI for caramels was 18.36 mg/g with a removal efficiency of 91.80% in the adsorption equilibrium state. The interaction mechanisms revealed that the caramel adsorption on EHGM/PDA/PEI was mostly mediated by protonated amine groups, followed by electron sharing. Two layers of caramels adhered onto EHGM/PDA/PEI were mainly mediated by electrovalent bonds between carboxylate and protonated amine. On average, one caramel molecule can be shared by 3–4 protonated amine groups of EHGM/PDA/PEI, which suggests a parallel sorption orientation. Four phenomenological mass transfer models [external diffusion resistance (EXTDR), internal diffusion resistance (INTDR), EXTDR–INTDR mixed, and adsorption onto active sites (AOAS)] proposed new and unique insights into the dynamic properties of the adsorption process.

Maximizing agricultural reuse of recycled nutrients: A spatially explicit assessment of environmental consequences and costs

Recovering nutrients from organic materials to reduce artificial fertilizer inputs requires the implementation of processing technologies and can involve considerable logistics and transportation costs. Reducing such costs by directly applying organic materials to agricultural land can contribute to pollution due to potential contaminants and unbalanced nutrient ratios. Assessing the cost of increased recycling requires a spatially explicit approach because availability of organic materials, nutrient demand and agro-ecosystem properties vary spatially. A multi-objective model was developed to estimate the trade-offs between costs of nutrient recovery and improvements in nutrient distribution for a case study area in The Netherlands. The evaluated recovery processes included solid-liquid separation followed by reverse osmosis to recover nutrients from pig manure which was compared to a conventional process via hygienisation and export. Results indicate that, even in a nutrient saturated area, replacement potential of artificial nitrogen (N) and phosphorus (P) fertilizers through locally reclaimed nutrients is limited to about 17% N and 55% P. A cost optimum was found when about 48% of the initial pig manure quantities were processed via nutrient recovery and directed to land. Increasing manure processing for nutrient recovery led to a redistribution of nutrients and trace metals (zinc (Zn) and copper (Cu)), resulting in more localized concentration. Zn and Cu were enriched by about 8% and 2%, respectively, when maximizing nutrient recovery. Our generic model offers a methodology to assess the trade-offs between increased recycling and associated spatial effects to facilitate sustainable recycling infrastructures for achieving more circular agriculture.

Selective removal of La(III) from mine tailwater using porous titanium phosphate monolith: Adsorption behavior and mechanism

The separation of rare earth elements from mine tailwater has received extensive attention because of the harm to the surrounding environment caused by the low concentrations of rare earth elements in tailwater produced by rare earth mining, and the high demand for rare earth elements in modern society. In this study, a porous titanium phosphate (TP) monolith material was prepared via a sol-gel process accompanied by a phase separation method for the adsorption of La(III) in mine tailwater. The results show that the adsorbent had a stable co-continuous porous skeletal structure. The adsorption performance of the adsorbent was almost unaffected when the solution pH was greater than 2. The PSO kinetic model and Langmuir isotherm model fit the experimental data well, and the maximum adsorption capacity at 30 °C was 253.97 mg·g−1. The TP monolith material exhibited excellent properties such as easy solid-liquid separation, good acid resistance and high adsorption capacity. In addition, the porous TP monolith had not only a certain selectivity for La(III), but also excellent adsorption-desorption and regeneration properties, which promote the application of TP monolith in the recovery of La(III) in actual wastewater. Finally, it was inferred from the mechanistic analysis that the phosphate groups on the material surface played a key role in the adsorption of La(III) by TP monolith materials.

EFFECT OF TRACE METAL FECL3 ON BIOGAS PRODUCTION IN INDUSTRIAL WASTEWATER TREATMENT WITH HIGH ORGANIC LOAD

Wastewater from the food industry that contains a high organic load, such as wastewater from the tofu manufacturing process, requires an appropriate and efficient treatment system to reduce pollutants before being discharged into water bodies. The most suitable treatment for high organic loads is the anaerobic treatment system. The anaerobic treatment process is a system of suspended media, attached media, or the combination thereof as a hybrid. This study uses a Hybrid Upflow Anaerobic Sludge Blanket (HUASB) reactor with the consideration that this reactor has advantages in maintaining high concentrations of biomass, high operating load rates, good decomposition capabilities, and good solid-liquid separation due to suitable granulation. The purpose of this study was to determine the effect of the addition of the trace metal FeCl3 on biogas production and the ability to remove pollutants in the tofu industrial process wastewater treatment in the HUASB reactor. The operation of the reactor uses variations in the concentration of tofu industrial waste water (75 and 100%) and trace metal concentrations (0.3–0.6 mg/L). The optimum biogas production was obtained with 8190 mL at a concentration of 75% tofu industrial waste water, a trace metal concentration of 0.6 mg/L FeCl3, and removal of COD and TSS of 94.09% and 94.2%, respectively. The role of the trace metal FeCl3in the anaerobic process shows that it is a source of nutrition for increasing the growth of microorganisms in anaerobic systems so that biogas production and pollutant removal are increased.

Removal of ultrafine colloidal particles from shale gas fracturing flowback fluid by microbubble-intensified flocculation: Effect of microbubble size

Shale gas fracturing flowback fluid (FFF) is characterized as the hazardous wastewater with high viscosity, large displacement, and complex components, which is difficult to deal with. Flocculation has been proven to be the most extensively applied treatment process considering its effortless operation, low energy consumption, and comparatively high efficiency. However, efficient removal of ultrafine colloidal particles (<10 μm) from FFF still remains a big challenge since their extremely stable properties. Herein, microbubbles (MBs) were introduced into the flocculation reaction to enhance the flocculation performance. When the median particle diameter (d50) of MBs reached 0.97 μm (which matched the size of selected colloidal particles), the turbidity removal rate was as high as 91.93 % at 0.70 g/L flocculant dosage, which was superior to traditional stir flocculation without MBs (66.67 %). Under this condition, the mean floc size reached the maximum value of 64.77 μm at 30 s after adding the flocculant. Meanwhile, the floc fractal dimension was significantly improved and the flocs held more resilient, which was beneficial for solid-liquid separation. The MBs worked by the trapping and bridging functions. Consequently, microbubble-intensified flocculation provided an advantageous way for the effective removal of ultrafine colloidal particles in FFF by controlling the bubble size appropriately.

Three-Dimensional Modeling of Spun-Bonded Nonwoven Meso-Structures.

As a type of fiber system, nonwoven fabric is ideal for solid-liquid separation and air filtration. With the wide application of nonwoven filter materials, it is crucial to explore the complex relationship between its meso structure and filtration performance. In this paper, we proposed a novel method for constructing the real meso-structure of spun-bonded nonwoven fabric using computer image processing technology based on the idea of a "point-line-body". Furthermore, the finite element method was adopted to predict filtration efficiencies based on the built 3D model. To verify the effectiveness of the constructed meso-structure and simulation model, filtration experiments were carried out on the fabric samples under different pollution particle sizes and inlet velocities. The experimental results show that the trends observed in the simulation results are consistent with those of the experimental results, with a relative error smaller than 10% for any individual datum.

Synthetic and biopolymers for lake restoration – An evaluation of flocculation mechanism and dewatering performance

In the frame of the global phosphorus (P) crisis and ongoing eutrophication issues in the environmental sector, lake sediment can be considered as an alternative P source after its removal from eutrophic lakes. However, high water contents make sediment dewatering a crucial step towards the efficient reusability of remaining solids. The application of polymeric substances facilitates solid-liquid separation by flocculation of suspended particles. To lower the environmental risk of contamination with toxic, non-biodegradable monomeric residues during and after the application of synthetic polyacrylamide(PAM)-based polymers, switching to natural polymeric substances (biopolymers), e.g., starch- or chitosan-based, is increasingly emphasized. The dewatering performance of four conventional PAM-based polymers was compared to two starch- and one chitosan-based biopolymer. Laboratory experiments were conducted to determine the dewatering rate, floc size and strength, and reject water quality. Biopolymers generally caused the formation of smaller but less shear-sensitive flocs, and lower P levels in the reject water compared to synthetic polymers. Dewatering performance was correlated to the most important functioning influencing polymer-specific properties intrinsic viscosity (polymer extension) and surface charge density (CD). Due to the high CD and low intrinsic viscosity of the biopolymers, electrostatic patch flocculation seems to be the favored flocculation mechanism, while for synthetic polymers bridging seems to be dominating. Solid-liquid separation technologies should be adjusted to the resulting floc size and structure, while surface CD and intrinsic viscosity are important properties for the choice of biopolymer. Overall, biopolymers can function as a more environmentally friendly alternative to synthetic products for lake sediment dewatering accompanied by the potential for P recovery.

Reusable self-floating carriers recover heavy metals from industrial wastewater through heterogeneous nucleation for resource reuse

Coagulation-flocculation in industrial wastewater treatment drives environmental pollution from landfilling heavy metal-laden sludge. Efficient separation of the sludge is crucial for cost-effective metal recovery. This study explored a new separation method of Cu2+, Ni2+, Zn2+ and Cr3+ via self-floating metal hydroxides assisted by hollow glass microsphere (HGM) carriers. The amount of OH− was stoichiometric to the positive charges of metal ions, mixed with 1 mg mL−1 HGM, causing metal hydroxides to attach to HGM surface via heterogeneous nucleation. The self-floating system removed 37.5% and 14.0% more metals than sedimentation at 50 and 200 mg L−1 metal concentrations. HGM additions increased the particle size of metal hydroxides by up to 12.5 times to that of HGM at 18.8 ± 1.1 µm, benefiting their solid-liquid separation. By pumping the wastewater downward in column reactor at velocities equal to or less than the self-floating sludge, 96.4% metals were removed in continuous flow. The recovery rates of HGM and metals reached 92.0 ± 2.2% and 92.7 ± 3.2%, and the concentration of the recovered metal reached 19,339 ± 394 mg L−1 for potential reutilization in industrial electroplating. This research investigated a new separation strategy based on solid self-flotation for sustainable treatment of metal-laden wastewater.

Achieving win-win outcomes with cerium-loaded porous aluminum sludge hydrogel microspheres for enhanced phosphate removal

Breaking the technical bottleneck of traditional powdered adsorbent in phosphate adsorption application treatment, a macroscopic high adsorption performance aluminum sludge-based composite hydrogel material was constructed to synergistically solve the problems of water eutrophication and aluminum sludge resourcization. In this study, porous Ce-modified aluminum sludge hydrogel microspheres (Ce-AlS-SA) were prepared to improve the surface chemical structure and microscopic morphology of the macroscopic adsorbent material to enhance the adsorption capacity and achieve effective solid-liquid separation. The best adsorption performance of the material (Ce-AlS12-SA1) was obtained when the Ce-AlS: SA: Na2CO3 was 12:1:1, and obtained the optimal adsorption conditions by Response Surface Method (RSM) with 1.5 mg/L of the dosage, 4 of pH and 50 mg/L of Cphosphate. The maximum adsorption of 20.36 mg P/g was obtained by the Langmuir model at 303 K, which was 2.92 times more than raw sludge. According to the Freundlich and pseudo-second-order kinetic model, the adsorption process is chemisorption; the multi-stage adsorption process is reflected in the intraparticle diffusion and film diffusion models. The main mechanisms combined with the characterization analysis are electrostatic gravity, ligand exchange, and inner-sphere complexation. Meanwhile, Ce-AlS12-SA1 shows good resistance to interference in the coexistence of multiple ions. Therefore, this material can be recognized as a new material with in-depth, diversified and practical needs for resourceful utilization, which is expected to achieve extensive engineering applications in the future.

Parallel filtration for solid-liquid separation: A case study of highly-efficient algal removal under parallel configuration driven by magnetic force

In traditional membrane filtration systems, the perpendicular permeate flow to the membrane surface causes the retentate to block the membrane pores, which results in an unavoidable cake resistance, thus making it difficult to achieve high filtration flux. In this study, a novel parallel filtration configuration driven by magnetic force was proposed for the removal of Microcystis flos-aquae. The results showed that the filtration flux under parallel filtration configuration reached 750,000 L⋅m−2⋅h−1 which is 3 times higher than the highest flux (280,000 L⋅m−2⋅h−1) reported in previous literature for algal removal. The permeate flow did not need to cross the cake layer, and the “pore size” of the filter chamber can be as high as 10 cm, thus resulting in negligible resistance (2.1 × 101 m−1) and higher filtration flux compared to traditional vertical filtration. For the magnetic-driven parallel filtration, the use of cationic polyacrylamide after polyaluminum chloride coagulation and magnetic particles (MPs) spiking was necessary. Increasing the MPs size and dosage further improved the filtration performance. Moreover, excessive flow velocity would affect the capture probability of algae-MPs aggregates by the magnetic field, which can be overcome by enhancing the magnetic field strength. We have developed a parallel filtration configuration for highly-efficient solid-liquid separation with simple and sustainable processes, which have the potential for rapid, efficient and large-scale applications in product purification, contaminant removal, and resource recycling in the future.

Predicting Escherichia coli levels in manure using machine learning in weeping wall and mechanical liquid solid separation systems.

An increased understanding of the interaction between manure management and public and environmental health has led to the development of Alternative Dairy Effluent Management Strategies (ADEMS). The efficiency of such ADEMS can be increased using mechanical solid-liquid-separator (SLS) or gravitational Weeping-Wall (WW) solid separation systems. In this research, using pilot study data from 96 samples, the chemical, physical, biological, seasonal, and structural parameters between SLS and WW of ADEM systems were compared. Parameters including sodium, potassium, total salts, volatile solids, pH, and E. coli levels were significantly different between the SLS and WW of ADEMS. The separated solid fraction of the dairy effluents had the lowest E. coli levels, which could have beneficial downstream implications in terms of microbial pollution control. To predict effluent quality and microbial pollution risk, we used Escherichia coli as the indicator organism, and a versatile machine learning, ensemble, stacked, super-learner model called E-C-MAN (Escherichia coli-Manure) was developed. Using pilot data, the E-C-MAN model was trained, and the trained model was validated with the test dataset. These results demonstrate that the heuristic E-C-MAN ensemble model can provide a pilot framework toward predicting Escherichia coli levels in manure treated by SLS or WW systems.

Greenhouse gas balances and yield-scaled emissions for storage and field application of organic fertilizers derived from cattle manure

Manure treatment such as anaerobic digestion and solid-liquid separation has shown a potential to abate greenhouse gas (GHG) emissions, but few studies have considered GHG emissions from both storage and field application regarding crop yield. In this study, four different organic fertilizers were studied: untreated cattle manure (CA); digestate of cattle manure anaerobically co-digested with grass-clover (DD); a liquid fraction from the separation of DD (LF); and a liquid fraction derived from a biogas desulfurization biofilter enriched with sulfur and ammonium (NS). The CH4, N2O and NH3 emissions during storage of CA, DD and LF between August and November 2020 (11 weeks) were quantified. Storage continued until April 2021 when these materials, as well as the NS fertilizer and a mineral NKS fertilizer, were applied at a rate of 100 kg total N ha−1 to spring barley. N2O emissions and soil mineral N content were monitored during the growing season. Overall, CH4 emissions during storage were the main source of GHG emissions independent of treatments, accounting for 85 %, 40 % and 11 % of total GHG emissions (based on field application of 100 kg ha−1 total N) from treatments CA, DD and LF, respectively. Anaerobic digestion and separation significantly reduced CH4 emissions during storage due to the diminished content of degradable organic matter available for methanogens. The N2O emissions from treatments CA, DD, and LF during storage were not significantly different. Treatments DD and LF emitted more NH3 than CA during storage, presumably because of higher pH and ammonium content. In the field experiment, the dilute solution of NS emitted the most N2O, while emissions from treatments CA, DD and LF were comparable. Yield-scaled GHG emissions for treatments CA, DD, LF and NS during both periods of storage and field were 44.4, 17.1, 8.5 and 24.3 kg CO2 eq hkg−1 grain yield, respectively. Anaerobic digestion with or without separation were thus effective strategies for the mitigation of GHG emissions from cattle manure in this study. Yields and nitrogen use efficiencies of the processed manure materials were not significantly different from those observed with the same N application rate as inorganic fertilizer, and hence anaerobic digestion with or without separation were promising GHG mitigation strategies.

Hydration makes a difference! How to tune protein complexes between liquid-liquid and liquid-solid phase separation.

Understanding how protein rich condensates formed upon liquid-liquid phase separation (LLPS) evolve into solid aggregates is of fundamental importance for several medical applications, since these are suspected to be hot-spots for many neurotoxic diseases. This requires developing experimental approaches to observe in real-time both LLPS and liquid-solid phase separation (LSPS), and to unravel the delicate balance of protein and water interactions dictating the free energy differences between the two. We present a vibrational THz spectroscopy approach that allows doing so from the point of view of hydration water. We focus on a cellular prion protein of high medical relevance, which we can drive to undergo either LLPS or LSPS with few mutations. We find that it is a subtle balance of hydrophobic and hydrophilic solvation contributions that allows tuning between LLPS and LSPS. Hydrophobic hydration provides an entropic driving force to phase separation, through the release of hydration water into the bulk. Water hydrating hydrophilic groups provides an enthalpic driving force to keep the condensates in a liquid state. As a result, when we modify the protein by a few mutations to be less hydrophilic, we shift from LLPS to LSPS. This molecular understanding paves the way for a rational design of proteins.

Effect of Mechanical Solids Separators on Potential Reduction of Methane Emissions From Dairy Manure Storage

Highlights Four mechanical manure separators were evaluated in on-farm studies. Mass balances and biochemical methane potential tests were conducted to measure on-farm separation efficiencies. Separator performance depended on environmental, material, and design factors. Over 70% solids separation and methane emission reduction potentials were achieved. Abstract. The separation efficiencies of four mechanical solid-liquid separation technologies and their effect on the reduction of methane production potential from dairy lagoons were studied using on-farm separator measurements and laboratory biomethane potential tests. The studied technologies included 1-stage sloped dual-screen, 2-stage sloped dual-screen, 1-stage horizontal scraped screen, and 1-stage sloped single-screen separators. The technologies were evaluated across various seasons on four dairies in California. On-farm sampling and measurements of the influent of flushed manure and the mass of the solids separated, as well as in-laboratory measurements of methane (CH4) production potential, were carried out. A mass balance approach was employed to determine the removal efficiencies of total and volatile solids (TS and VS) and nutrients, as well as methane emission reduction potential. The performance of the separators depended on manure characteristics, system design (e.g., screen size and orientation), separator operation and management (e.g., manure flow rate), and manure processing pit type and configuration. Among the four studied separator systems, the 2-stage sloped dual-screen separator showed the highest average TS and VS removal efficiencies, and methane emission potential reduction of 52.5%, 59.7%, and 55.8%, respectively. The 1-stage horizontal scraped screen separator had the lowest TS and VS removal efficiencies, and methane emission reduction potential of 6.3%, 9.3%, and 4.9%, respectively. The results have potential implications for nutrient and greenhouse gas management strategies and/or policies in agriculture. Keywords: Greenhouse gas, Lagoon, Manure management, Separation efficiency, Settling basin, Solid-liquid separation, Sustainable agriculture.

Feasibility Study on A Novel Waste Heat Recovery Process of Industrial Waste Salt Based on High Temperature Melting Dry Method

Industrial waste salt is mainly produced by industrial production processes of pesticides, drug synthesis, printing and dyeing, as well as solid-liquid separations, concentration and crystallization of solution, and sewage treatment, etc. At the present stage, the annual output of waste salt in China has exceeded 2.0×107 tons and the high-temperature melting method is considered to be a promising treatment method, but there are problems such as molten salt adhesion and agglomeration, unused high-temperature sensible heat, and waste of water resources. A novel process for waste heat recovery by high temperature melting dry method is proposed in this paper, using a combination of centrifugal granulation and waste heat recovery to dispose high-temperature molten salt and effectively recover heat. Through thermal equilibrium analysis and calculation, the waste heat recovering efficiency of the waste heat recovery using the novel process can reach up to 98%. Taking the annual treatment of 100,000 tons of waste salt as an example, the benefits of effective heat recovery converted to standard coal could be approximately 5 billion. While efficiently utilizing waste heat resources, the novel process brings considerable economic benefits to enterprises, has good industrial application prospects, and helps to advance the process of national hazardous waste solid waste treatment.