Solid-liquid Separation Technology Research Articles

Impacts of Liquid Fractions from Two Solid–Liquid Separation Technologies on the Soil Porosity, Ammonia, and Greenhouse Gas Emissions

Application of organic manure on farmland is one of the most important tasks in agricultural recycling. However, few studies have investigated the potential impact of different solid–liquid separation (SLS) technologies on soil porosity and greenhouse gas (GHG) emissions as a result of the application of liquid fractions (LFs). A microcosm experiment was conducted to track the emissions of ammonia (NH3), nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) from soils (1) without liquid manure application (CK), (2) with a raw dairy slurry (RM), (3) with the liquid fractions of mechanical solid–liquid separation (MS) technologies, and (4) with the LF of an enhanced solid–liquid separation technology including a flocculant (tannic acid, Ta) (MS + Ta). Soil porosities of different treatments were measured using computed tomography (CT). The saturated water conductivities of the RM and MS treatments were 53.38% and 78.63%, respectively, lower than that of the CK. The application of raw slurry and LFs reduced the gas diffusion due to the strong decrease in pore sizes >500 μm and increased gas emissions compared to the CK. Compared with RM, MS had greater N2O and lower CH4 emissions, whereas MS + Ta had lower NH3 and N2O emissions. MS had the greatest CO2-e emissions, mainly owing to high N2O emissions, followed by RM and MS + Ta. The implementation of a simple SLS led to an increase in nitrogen (N) loss and GHG emissions when the resultant LFs were applied to farmlands, whereas high emissions were reduced when a simple SLS was combined with a flocculant, such as Ta. Further research is required to elucidate the reduction mechanism and its effectiveness under field conditions.

Ultrasonic intensification of flocculation filtration for kaolinite: Unraveling mechanisms and performance gains

The mining industry produces substantial tailings, which present environmental challenges. This necessitates the adoption of efficient solid–liquid separation technologies to convert these tailings into a dewatered and environmentally manageable dry stack form. This work aims to investigate the transformative potential of ultrasonic treatment in the context of flocculation filtration for kaolinite dewatering and to elucidate the underlying mechanism. Through Uniform Design optimization, we determined the optimal conditions: 40 W ultrasound power, 12 min duration, and 40 kHz frequency. Experimental validation emphasized the effectiveness of these parameters, revealing a 2.02 % reduction in filter cake water content alongside a significant 2.5-fold enhancement in filtration rate. Furthermore, this combined treatment surpassed the performance of flocculation alone, resulting in the formation of smaller, more desirable flocs. The 3D structural analysis of the filter cake using micro-CT revealed that the synergistic application of ultrasound and flocculation led to a notable decrease in overall porosity. More significantly, there was a substantial reduction of isolated pores (down to 9.32 %). This phenomenon remarkably improved pore connectivity, enlarged pore and channel radii, and effectively mitigated capillary resistance during water transport. Additionally, the filter cake subjected to ultrasound and flocculation treatment showcased a uniform distribution of pore space, indicative of a promising trend towards homogenization across different sections. Ultrasound plays a role in refining flocs and suppressing segregation during tailings flocculation and filtration processes, primarily attributed to the cavitation and acoustic streaming effects of ultrasound. This comprehensive investigation sheds light on the transformative role of ultrasonic treatment in advancing the efficiency and performance of kaolinite dewatering processes.

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.

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.

A novel approach for nature gas hydrate separation: Downhole spiral-cyclone coupled hydraulic in-situ separation

The weakly cemented mixture slurry which is formed by the natural gas hydrate (NGH) solid-state fluidization mining method that is composed of natural gas hydrate, sediment and water. The downhole cyclone of NGH needs to deal with such problems as high viscosity, narrow radial working space, and difficult to adjust the split ratio. Directly using the conventional solid-liquid cyclone structure for downhole sand removal cannot obtain good separation performance. And the conventional separator does not have a tubular structure suitable for solid fluidization exploitation of NGH. Therefore, in order to solve the problem of weak cementation between NGH and sediment due to large sand production during NGH exploitation, this study proposes a new method to separate weakly cemented natural gas hydrate based on the principle of spiral-cyclone coupling. And the model of spiral-cyclone separator was established. This method can break weakly cemented solid-phase particles in the slurry, and the effective separation and removal of ultra-fine sediment with cross-scale and micron size. The research also designs and optimizes the separation device for NGH sand removal. According to numerical simulation and theoretical analysis, the separation efficiency is greater than 60% when the particle size is larger than 5 µm and the inlet velocity is between 2 m/s and 10 m/s. The research results show that the proposed spiral-cyclone separation method has the characteristics of high separation efficiency, strong sand removal, and can break the cementation bond between the sediment and natural gas hydrate, which is a high-efficiency solid-liquid separation technology.

Optimization of Air Flotation and the Combination of Air Flotation and Membrane Filtration in Microalgae Harvesting

On account of its small size and poor sedimentation performance, microalgae harvesting is restricted from a wider application. Air flotation is an efficient and fast solid–liquid separation technology, which has the potential to overcome the impediments of microalgae harvesting. In this study, factors influencing microalgae harvesting by air flotation were investigated. The results illustrated that bound extracellular organic matter (bEOM) had a greater effect on microalgae harvesting by air flotation, compared with dissolved extracellular organic matter (dEOM). Microalgae harvesting by air flotation in different growth stages proceeded, and the effect of air flotation in the heterotrophic stage was better than the autotrophic stage. The molecular weight distributions demonstrated that after air flotation, the proportion of high MW substance increased, while the proportion of low MW substance decreased, regardless of whether dEOM or bEOM. Membrane filtration was carried out for the algal solutions before and after air flotation. The membrane of pre-flotation algal solution had a higher critical flux of 51 L/m2·h than that of no-pre-flotation (24 L/m2·h), and, thus, pre-flotation had an active effect on membrane filtration in microalgae harvesting. Moreover, the combination of air flotation and membrane filtration provided an efficient technology for microalgae harvesting.

Separation efficiency of different solid-liquid separation technologies for slurry and gas emissions of liquid and solid fractions: A meta-analysis

Solid-liquid separation (SLS) technology is widely used in the slurry management in animal farms. This study conducted a comprehensive meta-analysis of 45 published articles to evaluate the differences in separation efficiencies (SEX-SF) of various SLSs and the changes of gas emissions before and after the separation during on-farm slurry storage. The results indicated that the SEX-SF of the untreated raw slurry and acidified slurry were consistently greater than those of the digested slurry, and centrifugation resulted in greater SEX-SF than the other mechanical methods. Both measured and simulated data showed that the centrifuge technology had greater reductions in greenhouse gas (GHG) emissions relative to the screw press (56.1–58.0% vs. 38.9–40.2% for untreated slurry, and 29.7–30.2% vs. 22.5–23.2% for digested slurry), mainly due to CH4 reduction. Additionally, we identify the need for further assessment of the environmental risks that are associated with SLSs for the development of an optimal slurry management chain.

Treatment of Manure and Digestate Liquid Fractions Using Membranes: Opportunities and Challenges.

Manure and digestate liquid fractions are nutrient-rich effluents that can be fractionated and concentrated using membranes. However, these membranes tend to foul due to organic matter, solids, colloids, and inorganic compounds including calcium, ammonium, sodium, sulfur, potassium, phosphorus, and magnesium contained in the feed. This review paper is intended as a theoretical and practical tool for the decision-making process during design of membrane-based systems aiming at processing manure liquid fractions. Firstly, this review paper gives an overview of the main physico-chemical characteristics of manure and digestates. Furthermore, solid-liquid separation technologies are described and the complexity of the physico-chemical variables affecting the separation process is discussed. The main factors influencing membrane fouling mechanisms, morphology and characteristics are described, as well as techniques covering membrane inspection and foulant analysis. Secondly, the effects of the feed characteristics, membrane operating conditions (pressure, cross-flow velocity, temperature), pH, flocculation-coagulation and membrane cleaning on fouling and membrane performance are presented. Finally, a summary of techniques for specific recovery of ammonia-nitrogen, phosphorus and removal of heavy metals for farm effluents is also presented.

Harmless Treatment and Comprehensive Utilization of Dairy Farming Waste Based on Artificial Intelligence

With the rapid development of social economy, people’s living standards are constantly improving. Dairy farming, as the main source of people’s demand for dairy products, plays an important role in the current social development. However, the disposal of its waste has always been a thorny issue. Therefore, the purpose of this paper is to study the harmless treatment and comprehensive utilization of dairy farming waste based on artificial intelligence. Finally, according to the actual investigation and comprehensive combination of artificial intelligence technology, this paper puts forward a dairy farming wastewater treatment system. The system uses artificial intelligence, multistage solid-liquid separation, biodegradation and other technologies, which can effectively treat the wastewater produced during dairy farming with good treatment effect and stable effluent index. In this paper, through experimental research, it is found that the quality of the treated wastewater is higher than the farmland irrigation standard by using the dairy farming wastewater treatment system based on artificial intelligence, and the effluent quality is lower than 200ml/g after advanced treatment. This will greatly improve the current ecological environment pollution, improve the scale process of aquaculture industry, provide an institutional system for the construction of waste discharge and utilization, and also provide new impetus for the green development of dairy farming industry.

An ecological sediment treatment technology based on zero emission and 4R concept

In order to reduce the amount of the contaminated sediment treatment and utilization, an ecological technology of sediment treatment was developed based on zero emission & 4R (Reduce, Recycle, Reuse, and Revolution) concept, centrifugal solid-liquid separation technology and high speed suspended solid settlement technology by gravity and polymeric flocculants and the biological contact oxidation technology. The polluted sediment can be accurately divided into gravel, sand, silt and clay by four-stage treatment process. The dewatered clay is made into the mixture soil of the sponge city facilities or other building materials, gravel and sand are directly used as concrete aggregate, permeable bricks and the silts are used for backfill and planting soil. The treatment efficiency of the ecological sediment treatment technology is higher than the traditional sediment treatment process used in China, and there is no secondary pollution and cost savings. It can be widely applied to quick treatment of the sediment in the polluted rivers, reservoirs and lakes, and construction wastes of subway and tunnels. The investment of the new treatment system is about CNY25 million Yuan for deposits of 2.48 million cubic meters. The innovative ecological treatment technology has been successfully used in the sediment treatment of the Qingxi River in Qingxi Town, Dongguan City, Guangdong Province in 2019.

Combining small-scale screening methods to predict microorganism floatability

Flotation is a common physico-chemical solid-liquid separation technology. It is applied in classical fields like minerals processing, pulp deinking and wastewater treatment and novel fields like biotechnology. The success of flotation is influenced by flotation key parameters. The aim of this study was to present a set of small-scale screening methods for the key flotation parameters particle size, particle hydrophobicity, bubble size and direct particle-bubble interaction. Experiments were performed with the model microorganism S. cerevisiae. Flotation was done in complex fermentation media and in isotonic saline, at varying pH and after flocculant addition. The goal, to combine small-scale laboratory methods to explain, predict and optimize yeast flotation results was achieved. Combining the methods can be used prospectively for wide screening of potential flotation additives, such as collectors, frothers and flocculants and to optimize microorganism floatability.

Solid-Liquid Separation Technology in Contaminated Soil Leaching

The background of this paper is contaminated soil leaching in old industrial relocation areas. This paper will explore and analyze the solid-liquid separation technologies used in contaminated soil leaching from two perspectives, including soil composition and soil texture. For instance, sedimentation separation, filtration separation and hydrocyclone separation technology applied in the soil solid-liquid separation. A horizontal comparison among technologies and corresponding equipment will be demonstrated as well as their characteristics.

A novel filtration system for point of care washing of cellular therapy products.

The cell therapy industry would greatly benefit from a simple point of care solution to remove dimethylsulphoxide (DMSO) from small-volume thawed cell suspensions before injection. A novel dead-end filtration device has been designed and validated, which takes advantage of the higher density of thawed cell suspensions to remove the DMSO and protein impurities from the cell suspension without fouling the filter membrane. The filter was designed to avoid fluid circuits and minimize the surface area that is contacted by the cell suspension, thus reducing cell losses by design. The filtration process was established through optimization of the fluid flow configuration, backflush cycles and filter geometry. Overall, this novel filtration device allows for a 1ml of thawed cryopreserved cell suspensions, containing 107 cells of a fetal lung fibroblast cell line (MRC-5), to be washed in less than 30min. More than 95% of the DMSO and up to 94% of the albumin-fluorescein-isothiocyanate content can be removed while the viable cell recovery is higher than 80%. It is also demonstrated that this system can be used for bone marrow-derived human mesenchymal stem cells with more than 73% cell recovery and 85% DMSO reduction. This is the first time that a dead end (normal) filtration process has been used to successfully wash high-density human cell suspensions. In practice, this novel solid-liquid separation technology fills the need for small-volume washing in closed processing systems for cellular therapies. Copyright © 2016 John Wiley & Sons, Ltd.

The Study on the Operating Characteristics of Algae-Contaminated Reservoir Water Using GAC-sand Dual Media Filter Flofilter

The problem of reservoir water quality caused by massive algae pollution keeps going serious, and the traditional solid-liquid separation technology generally fails to meet water quality standards. In the present study, GAC-sand-double-filtration flofilter was built to treat reservoir water derived from the Yellow River that has been polluted by high levels of algal biomass, with the running characteristics and operating results specifically investigated. The experimental results showed that, running effect was relatively superior when the dosage of PAFC was 4 mg/L (Al3+), the pressure of dissolved air was 0.4 Mpa, and the reflux ratio was 8%. Algal biomass fixed onto GAC and sand filter layer was mainly found in the carbon layer, which accounted for 97.4% of the total biomass (the highest value was 50.2 nmol p/g), and the biomass fixed onto carbon layer was 16.7 times of that fixed onto the sand layer (3.0 nmol p/g). Clearly, the removal of pollutants mainly occurred in the carbon layer. Also, the removal efficiency of particulate matter such as blue-green algae, turbidity, CODMn, UV254, NPOC, ammonia nitrogen was 96.48%, 92.40%, 92.56%, 57.40%, 52.50%, 51.60% and 75.67%, respectively. The odor was reduced from 4 to 0, and the content of geosmin and methylisoborneol was less than their detection limit, with the removal efficiency of chloroform and chlorodibromomethane as 60% and 55.1%, respectively. In general, the results showed that the flofilter process had imposed an efficient effect on the removal of algal biomass, odor substances and disinfection byproducts precursors.

Performance and techno-economic assessment of several solid–liquid separation technologies for processing dilute-acid pretreated corn stover

Solid–liquid separation of pretreated lignocellulosic biomass slurries is a critical unit operation employed in several different processes for production of fuels and chemicals. An effective separation process achieves good recovery of solute (sugars) and efficient dewatering of the biomass slurry. Dilute acid pretreated corn stover slurries were subjected to pressure and vacuum filtration and basket centrifugation to evaluate the technical and economic merits of these technologies. Experimental performance results were used to perform detailed process simulations and economic analysis using a 2000tonne/day biorefinery model to determine differences between the various filtration methods and their process settings. The filtration processes were able to successfully separate pretreated slurries into liquor and solid fractions with estimated sugar recoveries of at least 95% using a cake washing process. A continuous vacuum belt filter produced the most favorable process economics.

Study on Cross-Flow Solid-Liquid Separation Technology

The technology, device current situation , theory ,applied prospect of cross-flow solid-liquid separation have been summarized. It has been studied to making several cuneiform slots on the rotator of traditional crossflow filter, allowing the rotator forms convergence space with canister's inside wall. When suspending liquid fill into the cuneiform convergence space, it will cause kinetic press and improve the efficiency of filtrating. .

An overview of solid–liquid separation of residues from coal liquefaction processes

AbstractDirect coal liquefaction process typically produces mixed oils (60%) and gases (15%). The remainder is a high‐boiling viscous residue that contains oils, asphaltenes, unreacted coal, mineral matter and potentially valuable liquefaction catalyst. Effective separation of the components of the residue stream is important to the economic and environmental performance of the process. Solid–liquid separation technologies, such as filtration, hydrocyclones, centrifugation, critical solvent deashing and distillation have been reviewed in relation to their use in coal liquefaction processes. Individual operations used have not been completely satisfactory, and a better overall result is obtained when they are used in combination. © 2012 Canadian Society for Chemical Engineering

Characterization of tannery wastewater and biomass in a membrane bioreactor using respirometric analysis

Respirometric techniques and an activated sludge model (ASM) were applied for the characterization of tannery wastewater and biomass in a pilot plant membrane bioreactor (MBR) operating at high sludge age. The traditional respirometric tests and the IWA-ASM1 were modified to take into account the specific operating conditions, the solid–liquid separation technology and the wastewater complexity. As a result the wastewater biodegradable COD was fractionated into four components: readily biodegradable, rapidly hydrolysable, slowly hydrolysable and inorganic (due to the presence of reduced sulphur compounds). The kinetic and stoichiometric parameters of the biomass (heterotrophic and nitrifying) were estimated through the integration of model simulations and respirometric tests results. In particular the ammonium and nitrite-oxidizing biomasses were separately characterized: the growth kinetics of ammonium and nitrite-oxidizing bacteria resulted noticeably lower than the traditional reference values ( μ max,AOB = 0.25 d −1 e μ max,NOB = 0.23 d −1 at 20 °C, respectively). The ASM was finally used to confirm that the results of the wastewater and biomass characterization allow to properly simulate the mixed liquor suspended solids in the MBR pilot plant and the COD concentration in the effluent.

Membrane-media active collaboration (M-MAC): an alternative for solid-liquid separation in drinking water treatment

We have proposed membrane-media active collaboration (M-MAC), which is a collaboration between a membrane and media in one unit, as a new solid-liquid separation technology for drinking water treatment. Membrane filtration has a high separation capability, and media filtration provides a superior stability of finished water quality and has the economies of scale. An efficient and stable solid-liquid separation can be ensured by actively utilising the advantages of each filtration function. Hanshin's help-each-other filter (HHF), which installs submerged membranes at the centre gullet of a conventional media filter, is a prototypical configuration of M-MAC. HHF enables the chemical cleaning of a membrane as part of the periodical maintenance of the entire filter and utilises a regular discharge from the membrane as feed water for media filtration. These processes can eliminate problems peculiar to membrane technology, such as those related to chemical cleaning and recovery rate. Simulation and a preliminary experiment showed that HHF provides the same treated water quality as the conventional media filter. we expect that this technological development will lead to innovations in filtration technology and increase the number of options for better solid-liquid separation in drinking water treatment.

Abatement of Ammonia Emissions from Swine Lagoons Using Polymer-Enhanced Solid-Liquid Separation

A study was conducted to determine the effects of solid-liquid separation of liquid swine manure on ammonia emissions from lagoons. This determination was done at full-scale in two contiguous swine production units that had similar animal production management. One of these units was maintained as a control using the anaerobic lagoon treatment method. In the second production unit, solids were removed from liquid manure using an enhanced-polymer solid-liquid separation treatment prior to lagoon storage. The ammonia gas fluxes from both lagoons were measured simultaneously during a 10-month period (Feb.-Nov., 2004) using passive flux samplers. On average, the solid-liquid separation treatment separated 85% of total suspended solids (TSS), 60% of total solids (TS), 73% of chemical oxygen demand (COD), 81% of organic N, and 8% of total ammoniacal N (TAN) from the liquid entering the lagoon. Ammonia emissions from the anaerobic lagoon control totaled 12,542 kg N/yr (13,633 kg N/ha/yr). This compares to lower ammonia emissions of 3,426 kg N/yr (or 3,684 kg N/ha/yr) from the anaerobic lagoon treated with solid-liquid separation. Although water quality changes were modest in the treated lagoon with respect to the control, total annual NH3 emissions abatement in the lagoon with solid-liquid separation was 73% with respect to the anaerobic lagoon control. These results overall demonstrate that solid-liquid separation technologies can substantially reduce ammonia emissions from anaerobic swine lagoons.