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Energy use, together with consumption of raw materials, machine clothing, and wet end chemicals, are some of the most critical aspects in successful tissue making today. This work was aimed at developing a laboratory-scale method of estimating dewatering mechanisms, vacuum efficiency, and energy use of Through Air Drying (TAD) of tissue. When compared to pilot data, the results of the new laboratory method for investigating dewatering during TAD were in the same magnitude, around 24 to 26% dryness after vacuum dewatering, and 27 to 29% dryness after TAD molding. Sheet properties, such as caliper and surface profile, were evaluated and compared to commercial tissue sheets. The results indicate that it will be possible to precisely measure accurate dryness development and penetrated air volume for tissue sheet forming and TAD molding at a laboratory scale. This can contribute to the efforts of implementing a circular forest-based bioeconomy by increasing the fundamental understanding of dewatering of tissue paper materials, which is facilitated by improvements in energy use. The new method developed in this work will make it easier to assess ideas that are difficult to bring to pilot scale or full scale before learning more of the dewatering capabilities. The authors are convinced that improved knowledge of tissue dewatering mechanisms, forming, and material transport during and after TAD dewatering can increase the efficiency of the industrial manufacturing processes.

Technological comparison and system modelling of sewage sludge treatment are important in terms of sustainable development and climate change mitigation. Dewatering and drying are important processes for reducing volume for transportation and often a requirement for further sludge treatment. Inventory data on mass transfers and material and energy consumptions are therefore crucial in improving and understanding sludge management systems. Reviewing the scientific literature (2003–2021) revealed 55 and 21 datasets on dewatering and drying of sewage sludge, respectively. The scarcity of data did not allow for identifying detailed relationships between inputs and outputs for the technologies, but the reviewed data can serve as the first port of call when planning sludge management. The average total solid (TS) content obtained was statistically different for mechanical dewatering (MDW), deep dewatering, bio-drying (BDR) and thermal drying (TDR). Loss of volatile solids (VS) during dewatering is barely described, but a substantial VS loss was observed for TDR (8%) and BDR (27%). The use of chemical agents in MDW showed typical values of 5–15 g kg−1 TS. The use of energy is low for MDW (average of 0.12 and 0.26 kWh kg−1 TS for raw and digested sludges, respectively) but substantially higher for TDR (average of 3.8 kWh kg−1 TS). The justified inventory data for sludge dewatering and drying provide essential support to system modelling and technological comparison in future studies, but additional data from full-scale plants on energy consumption and the composition of removed water are strongly requested to improve the inventory.

The horizontal strain in the vacuum preloading/dewatering of dredged slurry is significant to the apparent clogging effect and estimation of surface settlement around a drain; however, it has seldom been investigated in previous studies. In this study, a vacuum consolidation model test assisted by particle image velocimetry (PIV) technology was conducted. The displacement vector field was obtained through PIV analysis and image processing; it was used to visually observe the deformation features around a drain. Based on the displacement field, the vertical/horizontal strains at varied radial distances were calculated to explain the ‘soil pile’ and apparent clogging effect. From the strain distribution with radial distances, a significant lateral compression zone near the drain and an extension zone at farther areas were confirmed. Furthermore, a simple explicit model was established to evaluate the horizontal strain within a prefabricated vertical drain unit cell considering a horizontal attenuated vacuum and compression/extension zone. Finally, this method was applied to predict the horizontal displacement in the model test. The results showed that the proposed method can estimate the lateral displacement of soft clay slurry fairly well.

This paper describes a model for the prediction of sinkhole collapse for two-dimensional and axisymmetric conditions. The model explains the arching effect on the threshold of collapse by a catenary arch or dome that tries to redirect the self-weight of the unstable soil to the adjacent stable mass. The collapse mechanism considers the vertical displacement of this unstable soil mass through vertical slip planes. An adapted Krynine's construction is used for predicting Mohr–Coulomb failure conditions on the base of the catenary arches for saturated or dry conditions, whereas a simple modification is proposed for unsaturated conditions. Upward growth of sinkholes is also discussed on the basis of the model described, as well as the dependency of the stability of arches on oscillations of the water level. Some case studies and experimental evidence are presented for evaluation and application of the proposed model. It is shown that the catenary arch assumption is an efficient but simple approach for the prediction of sinkhole growth and collapse.

This study proposes a new method using the combination of flocculation and prefabricated horizontal drain (PHD) assisted with vacuum pressure for rapid dewatering of high-water-content dredged slurry. First, to demonstrate the superiority of using PHD over the more commonly used prefabricated vertical drain (PVD), experiments were conducted to compare the dewatering performance between the PHD and the PVD. Then six model tests with the proposed dewatering method were performed with various contents of flocculant (anionic polyacrylamide (APAM)) to investigate the effect of APAM content on the dewatering process and soil properties (i.e. undrained shear strength, permeability and compressibility). Furthermore, particle size distributions of the slurry before and after model tests were measured to analyze the dewatering behavior and changes in material properties. Finally, particle loss during vacuum consolidation for various APAM contents were compared to study the flocculation effect on clogging problem. Results indicate that the proposed method can prevent significant bending deformation of the drain board and mitigate clogging of the drain filter and, thus, can significantly accelerate the dewatering process of high-water-content dredged slurry.

International audience; Dehydration is a critical step in many food processes. In this paper, we propose an original strategy, basedon experiments and modelling, to evaluate the performance of the compression dewatering of cassava and tohelp design dewatering equipment. The dewatering of various grated cassava roots was experimentally studiedthrough 42 experiments in a filtration–consolidation cell in the pressure range 4–21 bar. The dewateringperformance was evaluated in terms of moisture content limit and dewatering kinetics. Each filtration–consolidation experiment was first individually fitted with a model combining Hermia cake filtration andShirato consolidation mechanisms using an original systematic approach. Then, a global model, linking the cakefiltration and consolidation properties to the applied pressure, was validated over the whole set of experimentswith an average RMSE of 13% on the cake moisture content. The results demonstrated the relevance of thechosen identification procedure and modelling strategy for the design of a compression dewatering step.

Jet grouting (JG) is a well-known and often used geotechnical technique suitable for various applications, such as underpinnings and foundation reinforcement. The downsides are its comparatively high CO2 footprint, caused by the high amount of cement used, and accumulating waste, i.e., backflow slurry. The former, cement, is recognized for its CO2 emission potential and we are seeing new binders being introduced as surrogates, a process driven by the cement industry. The latter, spoil, must be taken care of on site. Here, the use of centrifuges is a promising approach to reduce waste. Centrifuges offer a high throughput in relation to space requirements when compared with other systems, e.g., chamber filter presses (CFP). This paper presents exemplary projects which used jet grouting for foundation reinforcement. For our analysis we are using data from a construction site that worked both with and without a centrifuge during different stages of its production time. This allowed a more precise analysis than comparing two different sites. Using the calculated CO2 footprint and other parameters, the operation of the centrifuge is evaluated regarding its environmental and economic impact, Paper presentation

Although cellulose nanomaterials have promising properties and performance in a wide application space, one hinderance to their wide scale industrial application has been associated with their economics of dewatering and drying and the ability to redisperse them back into suspension without introducing agglomerates or lose of yield. The present work investigates the dewatering of aqueous suspensions of cellulose nanofibrils (CNF) using ultrasound as a potentially low-cost, non-thermal, and scalable alternative to traditional heat-based drying methods such as spray drying. Specifically, we use vibrating mesh transducers to develop a direct-contact mode ultrasonic dewatering platform to remove water from CNF suspensions in a continuous manner. We demonstrate that the degree of dewatering is modulated by the number of transducers, their spatial configuration, and the flow rate of the CNF suspension. Water removal of up to 72 wt.% is achieved, corresponding to a final CNF concentration of 11 wt.% in 30 minutes using a twotransducer configuration. To evaluate the redispersibility of the dewatered CNF material, we use a microscopic analysis to quantify the morphology of the redispersed CNF suspension. By developing a custom software pipeline to automate image analysis, we compare the histograms of the dimensions (length, width) of the redispersed dewatered fibrils with the original CNF samples and observe no significant difference, suggesting that no agglomeration is induced due to ultrasonic dewatering. We estimate that this ultrasound dewatering technique is also energyefficient, consuming up to 36% less energy than the enthalpy of evaporation per kilogram of water. Together with the inexpensive cost of transducers (

Electrokinetic (EK) treatment is becoming increasingly important in the geotechnical field, especially for treating fine-grained soils. Above all, dredged sediments (slurries) need to be treated in order to be reutilised. Applying an electric potential difference within the soil, three phenomena take place: electrophoresis, electro-osmosis and electromigration. Negative particles move towards the positive electrode while water and cations move towards the negative electrode. Although the literature is full of cases describing the parameters that affect the EK process, there is a need to understand its limits and fields of application. This paper summarises the results collected from several case studies to understand the influence of some parameters on the efficiency of EK treatment, specifically in terms of dewatering rate. Soil conditions (soil type, pH, pore fluid salinity and water content) and set-up design parameters (electrode materials, configurations and operational mode) are analysed. Finally, parameter ranges for assessing the acceptability of electro-osmotic treatment are proposed. The results show that there are optimum values for the previously mentioned parameters that improve the dewatering and thus enhance the behaviour of the treated soils. EK treatment can be effective when applied on dredged sediments with low salinity.

Geotextile tube dewatering is a pre-treatment method utilized in the remediation of high-water content materials (i.e. sediments and slurries). However, given the association some contaminants (e.g. dioxins and furans, (i.e. PCDD/F)) have with particulate matter in these contaminated sediments, understanding the fate and transport of this particle matter in the dewatered effluent is essential. In this paper, pressure filtration tests (PFTs) were conducted to investigate the effect of pressure and filter cake formation on both geotextile filtration efficiency and effluent quality. Transport tests were then performed to evaluate the particle transport through the developed filter cake, as well as the hydraulic characteristics of the medium during dewatering. HYDRUS, a one-dimensional model contaminant transport model was then employed to simulate the experimental particle transport test results. Three different mechanisms of particle transport (i.e. attachment only, detachment only, both attachment and detachment) through saturated porous media were examined to identify the possible mechanisms of observed effluent particle concentration. HYDRUS modeling outputs suggest that both attachment and detachment mechanisms are involved in a given particle's fate and transport during geotextile dewatering. In addition, parameters such as confining pressure and filter cake properties affect the particle concentration in the effluent.

Considerable research has been conducted over the past decade by oil sands mining companies to improve the dewatering and strength properties of fluid fine tailings deposits in an effort to meet the regulatory and closure requirements. Commercially employed dewatering treatment technologies (inline flocculation, thickening, and centrifugation) may not be sufficient to develop the strength for the creation of trafficable landscape without the use of soft soil capping technologies. These treated tailings are continuously deposited creating soft and saturated deep deposits. Seasonal weathering may be an additional promising technology to further dewater the treated tailings and promote the development of shear strength at the surface. This paper presents the effects of seasonal weathering on dewatering and strength that were investigated by performing multiple cycles of freeze–thaw and alternate drying–wetting cycles on two types of treated tailings deposit. The results indicate that multiple cycles of seasonal weathering significantly increased the dewatering and strength properties. However, different parameters such as freezing gradient, number of seasonal cycles, and pore water chemistry play an influential role in changing the magnitude of the strength. The results also suggest that a minimum threshold strength value is required where the effects of rainfall rewetting had a minimal impact on strength reduction (the strength corresponding to the moisture content approaching the plastic limit).

In this study, the macro-structure of quartz flocs was assessed from X-ray computed tomography images. An image segmentation workflow was established to identify the floc sub-units that comprised each macro-floc, which permitted the macro-structure to be defined in terms of the number, size, and connectivity of the sub-units. A simplified structural model of non-penetrating spheres was used to understand the scaling relationships of the macro-floc properties. It was found that although sub-unit size varied widely, there was a limiting volume (2.8 × 106μm3), above which floc growth occurs only by sub-unit aggregation. This approach permits the quantification of macro-floc structure and composition in 3D on the scale of tens of μm to the mm scale. Knowledge of macro-floc structure allows a deeper understanding of the role of macro-floc breakage and re-arrangement in subsequent dewatering treatments such as thickening or filtration.

Groundwater level has to be lowered during deep excavation. A vertical curtain is usually adopted to control the drawdown both inside and outside a foundation pit in a built-up area. However, the cost and working difficulty increases substantially with the increasing depth of vertical curtains. In the manuscript, a kind of man-made horizontal seepage reducing body (HSRB) was introduced to shorten the vertical curtain depth and control drawdown. With the No. 4 shaft foundation pit of Guangyuan Project, Shanghai as background, HSRB was proposed in foundation pit dewatering. Microbially induced carbonate precipitation grouting technology was recommended to form an environment-friendly HSRB. Numerical method was used to simulate and understand the influence of position, thickness, and hydraulic conductivity of HSRB on groundwater level. The non-separated HSRB was better than the separate HSRB. Decreasing HSRB hydraulic conductivity was better than increasing HSRB depth. Four seepage modes are summarized considering vertical curtain penetration conditions into multi-aquifer, and the fifth seepage mode was formed for vertical curtain using man-made HSRB, which can be referred by similar engineering.

The conditions of the open pit drainage are usually very complex and, as a rule, insufficiently researched. When it comes to the exploitation of technical stone, especially limestone, the working environment is characterized by the crack porosity, and the present system of cracks and faults, apart from being in a complex relationship with each other, is characterized by greater or lesser water permeability as a function of the size of crack openings, type of material with which they are filled and degree of filling. As a result of exploitation works, the seismic impact that occurs as a result of blasting at the open pit, change in stress conditions due to the excavation and filling of the openings of existing cracks by the formation of transport roads and working plateaus at the open pit itself and during exploitation, the working environment conditions are changed, affecting the selection and functioning of drainage system of the open pit. Due to a number of affecting factors and their changes during exploitation, the selection and achievement of high efficiency of the open pit drainage system is a complex task. When it comes to testing the possibility of applying the water drainage from the open pit into surrounding rock massif, in order to achieve the expected high efficiency and safety of the drainage system, the working environment characteristics must be well known. This paper presents an analysis of application the conditions of the Kriveljski Kamen open pit drainage system by mine water drainage into massif [1]. This type of system was analyzed as a part of development the limestone exploitation project at this open pit with the basic idea of creating a reliable and economical system for protecting the open pit from water in the conditions of extremely high rainfall.

In order to avoid the energy consumption of dewatering and dust pollution in the preparation of non-sintered lightweight aggregates from dredged sediment, a new low-dust process of preparing non-sintered extruded wrap-shell aggregates (TH-WSLAs-W) by extrusion granulation is proposed and applied to produce TH-WSLAs-W baking-free bricks (TH-WSLAB-W). The basic physical properties (cylinder compressive strength, bulk density and water absorption) and microstructure of TH-WSLAs-W was explored. It shows that the curing agent will form a hydrophobic gel film around the sediment particles and form a network structure, which enhances the cylinder compressive strength (6.7 MPa) and frost resistance of TH-WSLAs-W. In addition, the interfacial transition zone among TH-WSLAB-Ws was studied by scanning electron microscope. It found that the micropore structure endow the TH-WSLAs-W with excellent water absorption and drainage property, promoting the hydration of cement, promising the integration of aggregate and cement, and its compressive strength reaches 20.5 MPa.

The unsatisfactory performance of the conventional swine wastewater treatment is drawing increasing attention due to the large amount of refractory chemical oxygen demand (COD), nitrogen, and phosphorus attached to the suspended solids (SS). In this study, for the first time, a novel process based on bio–coagulation dewatering followed by a bio–oxidation (BDBO) system was developed to treat swine wastewater containing high–strength SS, COD, TN, and TP. Firstly, after the bio–coagulation process, the removal efficiencies of SS, COD, NH3–N, and TP reached as high as 99.94%, 98.09%, 61.19%, and 99.92%, respectively. Secondly, the filtrate of the bio–coagulation dewatering process was introduced into the subsequent bio–oxidation process, in which the residual COD and NH3–N were further biodegraded in a sequence batch reactor. In addition, the dewatering performance of the concentrated swine slurry was substantially improved, with the specific resistance to filtration decreasing from 17.0 × 1012 to 0.3 × 1012 m/kg. Moreover, the concentrated swine slurry was pressed and filtered into a semi–dry cake after pilot–scale bio–coagulation dewatering treatment. Finally, the concentrations of COD and NH3–N in the effluent after the BDBO process, ranging between 150–170 mg/L and 75–90 mg/L, met the relevant discharge standard. Compared to traditional treatments, the BDBO system has excellent large–scale potential for improving the treatment efficiency, shortening the operation period, and reducing the processing costs, and is emerging as a cost–effective alternative for the treatment of wastewater containing high concentrations of SS, COD, TN, and TP.

The ability of cationized dialdehyde cellulose to improve the mechanical properties of paper was evaluated. The majority of cationized additives are synthesized by introducing cationic groups through chemical reactions. Here, cationized additives were produced in a more environmentally friendly manner by use of non-toxic and readily biodegradable deep eutectic-like solvent mixtures (DESs). The modified cellulose’s properties were characterized by FTIR, polarized-light optical microscopy, charge titrations, and SEM/EDX. The cationized additives were investigated as strength additives for papermaking. Three different amounts of cationic additive (2%, 5%, and 10%) were added to the pulp, and the properties of handsheets were studied. Because increasing the additive content can affect dewatering of the process, the dewatering capabilities of the pulps with additives were evaluated by Schopper-Riegler (°SR) value, water retention value (WRV), and vacuum dewatering. Finally, the recyclability of the DES was assessed in terms of cationization reaction efficiency and their effect on paper mechanical properties.

Over one third of the global population is not connected to a sewage system. Many low- and middle-income economy countries do not rely on infrastructure for centralised wastewater solutions. This results in blackwater being untreated, which leads to an increased public and environmental risk. As a solution in these often densely populated urban areas, cost-effective off-grid and decentralised systems seem to be an auspicious option. Most of these solutions include a dewatering step. However, current dewatering technologies (for example drying beds) are based on a high footprint and are not a sustainable solution for dense urban areas. A dewatering screw press offers a promising alternative that has the potential to solve these problems. It consists of a revolving screw that squeezes out the liquid in the blackwater through a sieve by compression. Hereby, the solid and liquid content is separated, and the blackwater is set up for further treatment. Screw presses already exist to treat wastewater on a large scale for entire cities, but not on a small scale. The goal of this thesis was to build a simple, robust and cost-effective screw press for up to 50 people, by reaching a high solid content in the sludge cake. The method to build such a system is by the means of agile product development. The idea behind this process is to work in many iterations with a large amount of testing. By this, it is possible to reach high adaptability to changes, and to minimise risks through early and numerous testing. This project started by building a minimum viable product, which puts the focus on the core mechanism of the screw press. Upon that, further prototypes are built and continuously improved by an iterative process including many trials. The tests are carried out with real blackwater in order to obtain as realistic a scenario as possible. The turbidity and the solid content are measured to assess the performance of the screw press. The final prototype is manufactured mostly by using metal sheet parts made of stainless steel. This made it possible to use simple and cost-effective manufacturing techniques. Other parts were produced by additive manufacturing, which allowed more complex designs like that of the screw to be realised at low costs. The results showed that by such a machine a high solid content of up to 30.3 wt% could be achieved. This is comparable to commercial screw presses. To summarise, it was possible to build a simple, robust and cost-effective screw press on a small scale. The system worked fine and was able to perform its task.

This chapter describes the treatment of fine coal tailings from a coal preparation facility, starting from the acceptance of tailings, or fine raw coal, into a plant thickener, which concentrates the tailings as a slurry, and produces clarified water for recirculation to the process plant. The methods of disposal of the thickened slurry tailings are discussed, from the types of filtration technologies available, to new methods, including deep cone paste thickening. All these dewatering processes are designed to recirculate the maximum amount of water to the plant and offer alternatives for the tailings solids disposal to the older solution of pumping to tailings pond, or dam.

The environmental concerns that come with the currently used traditional papermaking process where petroleum-based additives are used, has tempted researchers to study “green” additives by introducing environmentally friendly modifications of cellulose as an additive in the papermaking process. This thesis will spin further on that by producing additives with different charge densities and focus on to incorporate an etherification reaction into potentially greens systems based on non-toxic and readily biodegradable deep eutectic solvent (DES). Before modifying the cellulose with DES, an oxidation of cellulose to dialdehyde cellulose (DAC) with sodium periodate as oxidizing agent, took place. The high reactivity of the aldehyde groups in DAC serves as a starting material for further derivatization. The aldehyde content (AC) in the DAC was measured using titration. Additionally, the charge densities (mmol/g) of all modified pulps were determined by using a particle charge detector. The dewatering and drainage abilities of the different modified pulps was determined by measuring the drainage (°SR), the moisture ratio (g/g) before and after vacuum dewatering, and the water retention value (g/g). The tensile strength index was tested on the paper sheets and all parameters were compared with a reference pulp to find out which ionic DES was the most effective in modifying cellulose and using it as a wet-strength additive. From the result gained, one can see that there is a correlation between charge density and mechanical strength as well as the fibres capability to retain water. Generally, swelling considerably improves the strength properties of paper meanwhile the additives with strength-enhancing effects are also the additives that decrease the dewatering capacity. The conclusions from this work are that DESs reagents can work as sustainable modification methods for increasing the mechanical strength of papers together with oxidation of cellulose. In particular the cationic AH-G additive, which in accordance with other studies, show that cationic additives are better in increasing the mechanical strength than anionic because of their ability to adsorb to anionic fibers.

Dewatering in surface and underground mining is highly dependent on the permeability of fractured rocks, which is usually investigated by analytical and numerical methods. Analytical methods are used for simple, regular joint systems, while for complicated discrete fracture networks, numerical methods are more suitable. However, such numerical simulations demand considerable computation resources and are time-consuming for large-scale models. An attractive approach is to perform a rough mapping of the fractures into a lattice to apply effective medium theory. A computational code based on effective medium theory for calculating the overall permeability of fracture networks was developed. Several stochastic discrete fracture network models were generated with the fracture aperture distributed uniformly, correlated and uncorrelated with fracture trace length. The results showed that when the aperture was correlated or uncorrelated with trace length, the calculated mean permeability values by the effective medium theory method agreed well with numerical modelling. Also, approximated representative elementary volume was well fitted by numerical methods in the constant fracture aperture case. However, the calculated representative elementary volume by the effective medium theory method was smaller than the numerical estimation in the other two cases.

Resumo: A perfilagem eletrorresistiva da umidade no leito de areia quartzosa sobre tela vibratória em escala piloto foi tratado aqui. No que tange à configuração do eletrodos para medição de eletrorresistividade, o arranjo Wenner alfa clássico foi usado, exigindo espaçamento igual entre os eletrodos e mesma profundidade de penetração e alinhamento corretos. Aqui, a influência de pequenas variações na profundidade de penetração e falta de colinearidade dos eletrodos nas leituras de umidade, usando um eletrorresistivímetro digital e eletrodos de cobre, foi avaliada. As profundidades de penetração estudadas foram de 50 mm e 55 mm. Por sua vez, o desalinhamento testado dos eletrodos foi de 10 mm. O único fator que causou efeito estatisticamente significativo nas medições foi a profundidade de penetração de eletrodo, ao menos na faixa aqui estudada.Title: ELECTRICAL PROFILING OF VIBRATION-INDUCED DEWATERING OF SANDAbstract: Electrorresistive profiling of moisture inside a quartz sand bed on a pilot-scale vibrating screen was treated here. As electrode or probe configuration for resistivity measurement is concerned, the classical Wenner ? array was used, requiring equal electrode spacing, and correct penetration depth and alignment. Here, the influence of small variations in penetration depth and lack of probe collinearity on the moisture readings, using a digital earth resistance tester and copper wires as probes, was evaluated. The penetration depths studied were 50 mm and 55 mm. In turn, the electrode misalignment tested was 10 mm. The only factor that has caused a statistically significant effect in measurements was probe penetration depth, at least under the range tested here.

The spacing of PVDs is an essential factor affecting the consolidation effect of vacuum preloading. For exploring the influence of spacing of PVDs on the impact of sludge drainage consolidation, FeCl3, a commonly used inorganic coagulant, was used to pretreat the sludge. In the experiment a vacuum filtration test was carried out to determine the optimal addition amount of FeCl3, and then the landfill sludge was pretreated according to the FeCl3 optimal addition amount. And two different spacing of PVDs were used to carry out a vacuum preloading contrast test. Then, the drainage and settlement were recorded, and water content and vane shear strength (VSS) were measured after the experiment. Finally, Mercury intrusion porosimetry (MIP) was carried out to explore the pore characteristics of the sludge further. The main conclusions are as follows: After conditioning by FeCl3, the sludge’s flocculent structure was destroyed, the intracellular water was released, and the effect of drainage capacity was significantly improved. After the spacing of PVDs is halved, the average volume reduction ratio and shear strength increases, and the effect of advanced dewatering and volume reduction of sludge improved significantly, leading to a better consolidation effect. In the progress of vacuum drainage consolidation, halving the spacing of PVDs results in large pores transformation into small pores, and the range of drainage consolidation is greatly expanded.

Arthrospira platensis (A. platensis) is a microalga with a wide range of commercial uses. One of the main concerns that needs to be addressed in microalgae biorefineries is the costs associated with the harvesting and concentration steps. Filtration has been shown to be an effective technique for concentrating microalgae and recent studies have attempted to enhance membrane filtration by applying an external electric field to the filtration cell. This study consisted of assessing the use of electrically assisted filtration (electrofiltration) at 60 A/m2 and 1 bar for the dewatering of A. platensis, as well as the effect of pretreating the microalgae with ultrasounds (US) on the filtration process. Untreated A. platensis exhibited better filtration kinetics than US-treated A. platensis, and electrofiltration was found to increase the cake dryness. More protein and pigments were present in the US-treated microalgae solution compared to the untreated microalgae, which led to the presence of higher concentrations of protein and pigments in the filtrate streams after pressure filtration at 1 bar without the application of an external electric field. Electrofiltration was found to consume less energy compared to traditional drying techniques used for A. platensis. However, electrofiltration degrades the biocompounds present in the filtrate and cake due to pH changes and other electrophoresis phenomena, which shows the need to optimize the process in future work.

In situ extraction or “milking” of microalgae is a promising approach to reduce downstream costs in order to produce low-value substances such as lipids from microalgae in an economical way. Due to its ability to secrete high amounts of long-chain hydrocarbons to an extracellular matrix, the green microalga Botryococcus braunii is suitable for the process of in situ extraction as the cost intensive steps of harvesting, dewatering, and cell disruption could be omitted. Based on a previous study investigating various B. braunii strains in terms of growth, lipid accumulation, and solvent compatibility, the B. braunii strains Showa and Bot22 (both B race) were identified as potential candidates for the process of in situ extraction. In order to prove the suitability of these two strains for the process of in situ extraction, this study first determined the optimal extraction time using short-term in situ extraction over 7 days at different starting biomass concentrations of 1.5 and 2.5 g L−1. Furthermore, both strains were treated applying the optimal extraction time in long-term in situ extractions for 30 days to confirm the results from the short-term extractions. The results indicate a strain-dependent optimal extraction time of 300 min day−1 for strain Showa and 200 min day−1 for strain Bot22. During long-term in situ extraction for 30 days, hydrocarbon productivity was 16.99 mg L−1 day−1 (10.53 mg gDW−1 day−1) for strain Showa and 14.53 mg L−1 day−1 (10.48 mg gDW−1 day−1) for strain Bot22. Furthermore, a direct correlation between hydrocarbon productivity achieved by in situ extraction and the hydrocarbon concentration in the biomass of the respective strain could be established. It could be shown that the consideration of the effective extraction time and the phase boundary area is required to calculate an extraction system independent value for the comparison of different extraction setups.

An electroassisted filtration technique has been employed to improve dewatering of a suspension of microfibrillated cellulose (MFC) produced via 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-mediat...

Achieve high-efficiency dewatering and purification of emulsion is not always feasible using conventional single method. A centrifugal separator embedded in electric field can achieve efficient dem...

This study was conducted to develop a machine that continuously operates two processing operations (grating and pressing) for cassava grates production. Due to a lack of concrete literature for the type of screws to be used for the continuous dewatering operation for cassava, three types of screws were evaluated to identify which is the most suitable screw to be used. The screws were tested using five (5) kg cassava tubers as input materials and the capacity and rate of moisture removal were measured as a response. The variable pitch screw failed to show its performance due to the failure occurs during evaluation. A t-test analysis was used to analyze the significant difference between the remaining two screws. The analysis shows that the tapered screw shaft shows the most promising results having an average output capacity of 5.35 kg/hr and rate of moisture removal of 4.69 kg/hr.

Dewatering of anaerobic digested (AD) sludge containing waste-activated sludge (WAS) from enhanced biological phosphorus removal (EBPR) poses numerous challenges including poor dewaterability, struvite scale formation, and recycling of high N and P levels in the sludge liquor to the treatment process. A full-scale water reclamation facility was investigated to mitigate these problems by experimenting with direct dewatering of EBPR WAS, bypassing the AD step. The investigations experimented with various blends of AD primary sludge with undigested thickened WAS to achieve dewatering performance improvements and overall operational cost savings. Direct thickened WAS dewatering has had many positive impacts including enhanced sludge cake solids concentration, reduced chemical use for facility operations, reduced struvite scaling, reduced biogas conditioning media servicing, eliminated need for centrate treatment, recovered capacity of existing unit operations including anaerobic digesters, and eliminated several proposed capital improvement projects that were previously deemed necessary. Although bypassing of WAS to AD reduced total biogas production, the specific gas yield increased to meet all of the facility's biogas demands and minimized excess gas flaring. The overall biosolids production mass increased causing increased transportation costs for disposal and caused notable odors, both of which are being currently investigated. PRACTITIONER POINTS: Direct WAS dewatering bypassing anaerobic digestion yields operational and process benefits in an EBPR water resource recovery facility Dewatered cake solids were increased compared with combined primary and WAS anaerobic digestion and dewatering Nutrient loads in sludge processing returns streams and operational costs are reduced by direct WAS dewatering.

Most sludges are dewatered using mechanical dewatering systems that can bring the weight percentage of the sludge solids up to a maximum of about 40 TS%. This study examined a new way to enhance pr...

Bioleaching is of increasing interest because of its high efficiency in improving sludge dewaterability and removing heavy metals from sewage sludge. However, in traditional single-phase bioleaching, a high-efficiency level cannot be maintained continuously, wherein the microbial synergistic effect is disrupted at a low pH environment. Therefore, in this study, a series of multi-compartment-baffled flow trials were performed to assess the effects of phase separation on sludge bioleaching by comparing a two-phase trial with two single-phase trials. Energy substrate and part of the bioleached sludge were introduced separately into two compartments to form two phases, namely selection phase and bioleaching phase. The results show that phase separation apparently shortened the start-up duration of sludge bioleaching from 7 days in a single-phase bioleaching to 4 days in two-phase bioleaching. The dewaterability of bioleached sludge was also enhanced by phase separation with relative decreases of 25.0-33.3% for specific resistance to filtration and 14.2% for capillary suction time, which was attributed to lower pH values, zeta potential closer to zero, and less dissolved organic matter in bioleached sludge after two-phase bioleaching. Phase separation generally increased the removal ratios of heavy metals during sludge bioleaching by -0.79 to 2.60%, 11.06 to 15.04%, 4.45 to 11.03%, 17.98 to 23.46%, 7.20 to 9.28%, -9.22 to -2.46%, and -6.72 to -10.68% for As, Cd, Cr, Cu, Ni, Pb, and Zn, respectively. Phase separation also enriched the Acidithiobacillus spp. and reduced the inactivation of acid-tolerant fungi, which can be conducive to better synergistic effect, and therefore maintain long-term stable state in the bioleaching phase of the two-phase bioleaching process.

In this study, a two-dimensional consolidation solution for geotextile tubes filled with fine-grained material was presented. The solution is based on a combination of various methods that were modified or extended to take into account the change in tube shape, the nonlinear interaction between the soil and geotextile, and the water content distribution of the tube during consolidation. Using the proposed solution, the effect of various necessary input parameters was investigated. Thereafter, numerous dewatering and consolidation properties of various combinations of geotextiles and fill materials were obtained from several tests such as the half cross-section test, hanging bag tests, and geotextile tube demonstration test. Results of the study have shown that the method presented in this study can well-represent the consolidation behavior of geotextile tubes filled with fine-grained material.

Anaerobic digestion is an important way for maintaining sewage sludge stability, reduction, and resource recovery. However, the low organic content generally limits methane production. Recently, thermal hydrolysis has been widely used for sludge pretreatment to improve the anaerobic digestion efficiency. Generally, an increased temperature is preferred to enhance the solubility of organic matters in the sludge. However, high energy requirement comes with increased temperature. Application of low-temperature thermal treatment could overcome this drawback. However, the appropriate low-temperature pretreatment time is still uncertain. In this study, an extended contact time with low thermal pretreatment (90 °C) was chosen to realize a more efficient and economical digestion process of low-organic content sludge. The results demonstrated that the solubilization of proteins and carbohydrates was significantly promoted by the contact time-extended thermal hydrolysis pretreatment. The following anaerobic digestion efficiency of low-organic content sludge was also dramatically improved with the prolonged contact time. The maximum methane production could reach around 294.73 mL/gVS after 36 h of 90 °C treatment, which was 5.56 times that of the untreated groups. Additionally, based on the energy balance calculation, extending the thermal hydrolysis time resulted in a more economically feasible anaerobic digestion than increasing the temperature. The dewatering properties and the stability of the heavy metals were also reinforced, implying the advanced deep utilization of the digested low-organic content sludge. In conclusion, sludge pretreated by low-temperature thermal hydrolysis with a prolonged contact time could be more effective for low-organic content sludge treatment and disposal.

Beneficiation of coal is a water intensive process, and the water is recovered in downstream operations in the high rate thickener (HRT) and vacuum belt filtration (VBF). Clean coal particles entering the HRT have an inherent tendency to enter the overflow because they are extremely fine and hydrophobic. Hence, flocculants (polymers) are used to floc the ultrafine particles so that they settle and enter the underflow. Ultrafine coal particles (−37 μ), which are highly hydrophobic, if present in the stream, will not be efficiently captured by using flocculants alone. This is observed in the normal plant operation at one of the beneficiation plants in the Jharia region, Jharkhand, India. Approximately 6–7% of the feed to the HRT enters the over flow (supernatant water). Hence, this amount of clean coal particles is not recovered and account for production losses. A comprehensive settling and dewatering test work was conducted with clean coal slurry using several commercially available reagents. Studies were also done on different combinations of reagents, including coagulants and surfactants along with flocculants, to improve the settling behavior of the coal particles. The reagents were assessed based on their performance with respect to settling rates, overflow water clarity, and compaction of the underflow solids. Emphasis was given to the ability of the reagents in compacting thickener underflow to higher densities so that maximum water could be recovered from the thickener. Pretreatment of highly hydrophobic coal slurry with a combination of coagulant and surfactant followed by flocculation showed very good settling characteristics with clear overflow.

A sound understanding of groundwater engineering principles is a prerequisite for effective construction dewatering and the associated pumping tests. This paper makes practical recommendations to improve dewatering designs in reclaimed land in Hong Kong and the interpretation of groundwater monitoring data. The paper first introduces the reader to the hydrogeology of Hong Kong and its implications on dewatering. It then draws upon experiences in Hong Kong, reviewing and recommending best practices in groundwater monitoring, and the design of extraction and recharge wells.

Nanoparticles can undergo aging phenomena that change their physical and chemical properties in sewage treatment systems. However, the effect of aged nanoparticles under long-term low concentrations on the dewatering performance of activated sludge in sewage treatment systems has not been reported yet. Here, we compared the chronic effects of pristine and aged TiO2 nanoparticles on sludge dewatering index including specific resistance to filtration (SRF) and bound water (BW) in the sequencing batch reactor (SBR) with the µg/L concentration levels and the relevant mechanisms were analyzed. The results show that the aging experiment in sludge supernatant could change the photosensitivity and water stability of nanoparticles, which was mainly due to the changes in the zeta potential and energy band of the particle, and ultimately attributed to the combined effect of particle surface inclusions such as organic matter and inorganic salt. At 10µg/L, nanoparticles could reduce the dewaterability of sludge, but at 100µg/L, nanoparticles could improve the dewaterability of sludge, because 10µg/L promoted the secretion of extracellular polymeric substance (EPS), regulated the structure of sludge flora and increased the abundance of secreting quorum sensing-acyl-homoserine lactones (QS-AHL) and EPS genera, while the corresponding exposure results of 100µg/L were the opposite, due to the damage and necrosis exposure effects of 100µg/L under long-term light, which reduced EPS production and increased sludge density. Interestingly, aging could alleviate the effects of two exposure concentrations on sludge dewatering, mainly being attributed to the decrease of the photoactivity of nanoparticles. The results of this study show that environmental aging could slow down, but cannot reverse the results of exposure to specific concentrations of nanoparticles. However, the ecological effects of photosensitive nanoparticles with two environmentally-relevant concentration levels of ug/L were significantly different, which should be refined and confirmed again in freshwater environment to provide a basis for subsequent scientific management and control of photosensitive nanoparticles.

This paper reports the dewatering scheme of a deep excavation in sandy pebble strata. The excavation is in high permeability strata and is close to the Yellow River, making the dewatering difficult during construction. At present, few researchers have specially studied the dewatering scheme of deep excavations in strong permeable strata near the water resource. Field pumping test was conducted before the excavation activity, and the permeability coefficient of the strata was obtained by reverse analysis. According to the characteristics of the project, the dewatering scheme of “ waterproof curtain + base grouting + pumping ” was proposed. The influence of vertical waterproof curtain and base grouting on dewatering was analyzed by numerical simulation. In the construction process, the field water table and ground settlement were measured. The results show that (1) the groundwater table versus permeability coefficient curve shows three different stages and (2) the dewatering scheme of “ waterproof curtain + base grouting + pumping ” is effective for deep excavation in strong permeable strata.

Dewatering is considered as extremely significant and primary step to enhance the quality of lignite. A great number of research focus on conventional fluidized-bed drying technology or dynamics. I...

This work investigates the effect of partially hydrophobic grafted polymers on flocculation and dewatering of oil sands mature fine tailings. Here, we combine confocal microscopy and rheology to investigate how the graft density of ethylene-propylene-diene grafted with hydrolyzed poly(methyl acrylate) (EPDM-g-HPMA) affects its dispersion in water and flocculation efficiency in terms of sediment solids content and long-term dewatering of oil sands tailings. Increasing the graft density from 30 to 50% makes the flocculant easier to disperse, increases the rate of initial dewatering, and also enhances the viscoelastic response of the flocculated sediments. Conversely, the long-term rheological properties of the flocculated sediments were similar for all flocculants. Tri-dimensional microscopic details of the spatial distribution of water within the flocculated sludge provide novel insights into the performance of the flocculants. Increasing the graft density in EPDM-g-HPMA traps more water within the individual flocs and, consequently, decreases the post-flocculation dewatering rate. Our systematic approach confirms the importance of the spatial distribution of water in the flocculated sediment, which depends on how the flocculant is dispersed and how it retains water in the flocs.

Soil in situ remediation, such as washing, always produces much sludge that has the characteristics of a high fine particle proportion, high moisture content, and high metal content. Problems such ...

The problems of treatment of various mineralized effluents with the use of reverse osmosis and nanofiltration are considered. It is noted that concentrates from reverse osmosis plants, which have high concentrations of salts and organic substances and are difficult to utilize cause a serious environmental problem. It is proposed to use the separation of the concentrates to solutions containing their components depending on the value of their rejection using nanofiltration membranes. Thus, the concentrates from reverse osmosis plants after the treatment of wastewater, sludge water after dewatering of sludge, as well as concentrates from the municipal solid waste (MSW) landfill leachate treatment plants can be separated to solutions with a high concentration of organic substances and salines (containing ammonium salts), the volumes of which are 10–20-fold lower than the volumes of concentrates. It is demonstrated by way of example of the effluents from ion exchange softening plants, which are a mixture of sodium and calcium chlorides, how multicomponent solutions can be separated to highly concentrated solutions of sodium chloride and calcium chloride to reuse sodium chloride and purified water in production. A technology of separation of solutions is described, which utilizes the dilution of the concentrate with deionized water, which makes it possible to achieve the separation of the solutions to the components depending on their selectivity—the degree of their rejection by nanofiltration membranes.

Thickening-dewatering process is widely used for solid–liquid separation in mineral processing plants. Usually, the feed quantity of the thickener is an uncertain variable, so the underflow concentration of the thickener cannot be accurately predicted, which may result in improper operation and high security risk. This paper proposes a stochastic chance-constrained optimization framework for the thickening-dewatering process with the uncertain feed quantity. Firstly, a feed quantity predictive model is established by gray correlation analysis (GCA) and partial least squares (PLS) to reduce the uncertainty of the feed quantity. Then, the stochastic chance-constrained optimization model of the thickening-dewatering process is established to minimize the energy economic index (EEI). In order to solve the stochastic chance-constrained optimization model, the nonlinear time-of-use electricity price function in the objective is linearized, and then the stochastic chance-constrained optimization model is transformed into a deterministic model. The cases study illustrate that the optimization framework can reduce the EEI and the security risk of the thickening-dewatering process.

Solid bowl centrifuges (SBCs) find wide industrial applications for various solid–liquid separation tasks. Despite its importance, the information on the effects of the operational variables of an SBC on the dewatering performance is limited, even with some conflicting results, especially for the effects of the weir height and differential speed on the solids recovery. In the present work, a systematic simulation study was carried out using a validated SBC model to investigate the effects of various process parameters on the solids recovery. The simulation results matched well with the reported experimental findings in the literature. Additionally, the present work provides insights on why there is a disagreement between the experimental findings of the effects of the differential speed and the weir height.

During the cleaning and further treatment of municipal wastewater, sediments are formed, which are extremely dangerous from a sanitary and hygienic point of view, poorly dewatered, have high humidity (over 90%), large volumes (up to 3% of wastewater consumption), contain organic substances, pathogens, heavy metals, etc. In Ukraine, at most wastewater treatment plants, sewage sludge is mostly piled up on sludge sites after minimal treatment. Effective processing and disposal of sewage sludge in order to reduce the negative impact on the environment, as well as the use of sewage sludge as secondary raw materials, is an actual, complex and urgent task. The key link in the existing process of treatment and disposal of sewage sludge is their dewatering. When designing facilities for the treatment and disposal of sewage sludge, advanced technologies should be used, the use of which is based on scientific and technical research. The article reviews the results of research on the intensification of existing mechanical methods of sewage sludge. One of the most effective methods of intensifying the process of dewatering sewage sludge is electro-dewatering, which involves the application of an electric field during mechanical dewatering of sludge. Electro-dewatering technology makes it possible to reduce the humidity of sediments to 20...40%, reduce the concentration of heavy metals and pathogens in sediments, etc. The purpose of this work is to study the possibility of electro-dewatering of activated sludge from secondary settling tanks of municipal wastewater treatment plants in Lviv. Empirical research methods were used. A laboratory scale has been designed for electro-dewatering of sewage sludge. Activated sludge with a moisture content of 98% was studied. It is shown that the effect of activated sludge dewatering, depending on the duration of its treatment, is an S-shaped curve that resembles a kinetic autocatalytic reaction with three periods: induction, main, and fading. The possibility of electro-dewatering of sewage sludge with a maximum dewatering effect of 60% has been proven. Therefore, it is proposed to carry out mechanical dewatering of city sewage sludge using an electric field., Під час очищення та доочищення комунальних стічних вод утворюються осади, які надзвичайно небезпечні у санітарно-гігієнічному відношенні, погано зневоднюються, мають високу вологість (понад 90%), великі об’єми (до 3% від витрати стічних вод), містять у собі органічні речовини, патогени, важкі метали тощо. В Україні на більшості каналізаційних очисних станцій осади стічних вод переважно нагромаджують на мулових майданчиках після мінімальної обробки. Ефективна обробка та утилізація осадів з метою зменшення негативного впливу на довкілля, а також використання осадів як вторинної сировини є актуальним, складним та невідкладним завданням. Ключовою ланкою в існуючому процесі обробки та утилізації осадів є їх зневоднення. При проектуванні споруд оброблення й утилізації осадів стічних вод слід застосовувати прогресивні технології, використання яких базується на науково-технічних дослідженнях. У статті оглянуто результати досліджень щодо інтенсифікації існуючих механічних способів обробки осадів. Одним із найефективніших способів інтенсифікації процесу зневоднення осадів стічних вод є електрозневоднення, яке передбачає застосування електричного поля під час механічного зневоднення осадів. Технологія електрозневоднення дає змогу зменшити вологість осадів до 20...40%, зменшити концентрацію важких металів та патогенів в осадах тощо. Метою даної роботи є дослідження можливості електрозневоднення активного мулу із вторинних відстійників міських каналізаційних очисних споруд м.Львів. Використовували емпіричні методи дослідження. Для електрозневоднення осаду стічних вод запроектовано лабораторний стенд. Досліджували активний мул вологістю 98%. Показано, що ефект зневоднення активного мулу залежно від тривалості його оброблення являє собою S-подібну криву, що нагадує кінетичну автокаталітичну реакцію з трьома періодами: індукції, основним, загасаючим. Доведено можливість електрозневоднення осадів стічних вод з максимальним ефектом зневоднення 60%. Тому пропонується проводити механічне зневоднення осадів міських стічних вод із застосуванням електричного поля.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) During the stages involved in the water treatment process, sludge is formed, which is characterized as solid waste and, therefore, its destination must be compatible with the guidelines of the PNRS - Law 12.305/2010, prioritizing reduction, reuse and recycling. In this sense, dewatering, understood as a method of reducing the volume of sludge, meets the requirements established by the National Policy on Solid Waste. Dewatering is characterized by the removal of free water, supernatant found in the interstices of solids, using natural or mechanical systems. Drainage beds, designated as DB and previously conceptualized as drying beds, are among these natural systems. This technique has shown to be interesting, despite the lack of research using polymers as conditioning. Several authors defend the theory that the WTP sludge does not need a polymer to be dewatered, as it already has chemical conditioners, introduced in the water treatment process, which would facilitate dewatering. Thus, the main objective of this research was to study the application of polymers as a conditioner in the WTP sludge applied to the DB, with a view to improving efficiency and dewatering. For this purpose, a bench scale Drainage Bed system was used, with a total of 108 drainages, including tests without polymer (SP) and with polymer (CP), with 4 geosynthetics (3 non-woven geotextiles and a woven geotextile ), a fixed total solids (ST) content of the sludge of 2% and 3 sludge layer heights (H10, H30 and H50 cm). Subsequently, in order to choose the polymer to be applied to the DBs, cone tests were carried out with different types of polymers, concentrations and dosages, with the respective geotextiles. These results were applied to the BD system, characterized as CP-cone for each geotextile tested. In order to study another polymer selection method, the BD system itself was used, since the TAS (Solid Application Rate) between these two methods were considered different. Thus, tests were performed, characterized as CP-alternative, using the same geotextiles. The analysis of the results highlighted that the CP - alternative tests were able to increase the removal rates, mainly for higher hydraulic loads, with TAS > 6 kg/m2 , with superior quality of drains for all hydraulic loads; the alternative method would be the most indicated because it presented high removal with satisfactory quality. Only the non-woven geotextile GTNT600 showed no statistical difference in dry retained mass regardless of the hydraulic load and the method applied for polymer selection. Regarding the efficiencies, the EF (%) was > 98% for the CP tests. For the ESST (%) the values were > 96%. Higher hydraulic loads obtained higher TSS removal efficiencies, regardless of the test configuration (SP and CP – cone and alternative) with values above 98%. Ao longo das etapas envolvidas no processo de tratamento da água ocorre a formação de lodo, o qual é caracterizado como resíduo sólido e, portanto sua destinação deve ser compatível com as diretrizes da PNRS – Lei 12.305/2010, priorizando a redução, reuso e reciclagem. Nesse sentido o desaguamento, compreendido como um método de diminuição do volume de lodo atende ao estabelecido pela Política Nacional de Resíduos Sólidos. O desaguamento é caracterizado pela remoção da água livre, sobrenadante encontrada nos interstícios dos sólidos, utilizando sistemas naturais ou mecânicos. Os leitos de drenagem, designados como LD e anteriormente conceituados como leitos de secagem estão entre estes sistemas naturais. Essa técnica tem se mostrado interessante, não obstante perceba-se a ausência de pesquisas utilizando polímeros como condicionante. Vários autores defendem a teoria de que o lodo de ETA não necessita de polímero para ser desaguado, pois já possui condicionantes químicos, introduzidos no processo de tratamento da água, que facilitariam o desaguamento. Assim, o objetivo principal desta pesquisa foi estudar a aplicação de polímeros, como condicionante nos lodos de ETA aplicados nos LD, com vistas a melhora da eficiência e do desaguamento. Para tanto, foi utilizado um sistema de Leitos de Drenagem em escala de bancada, sendo realizado ao todo 108 drenagens, dentre ensaios sem polímero (SP) e com polímero (CP), com 4 geossintéticos (3 geotêxteis não-tecidos e um geotêxtil tecido), um teor de sólidos totais (ST) fixo do lodo de 2% e 3 alturas de camada de lodo (H10, H30 e H50 cm). Posteriormente, para a escolha do polímero a ser aplicado nos LDs, foram realizado ensaios de cone com diferentes tipos de polímeros, concentrações e dosagens, com os respectivos geotêxteis. Esses resultados foram aplicados ao sistema de LD, caracterizados como CP-cone para cada geotêxtil ensaiado. Com o intuito de estudar um outro método de seleção de polímeros, foi utilizado o próprio sistema de LD, já que a TAS (Taxa de aplicação de sólidos) dentre esses dois métodos foram consideradas diferentes. Assim, foram realizados ensaios, caracterizados como CP alternativo, utilizando os mesmos geotêxteis. A análise dos resultados destacou que os ensaios CP - alternativo conseguiram aumentar as taxas de remoção, principalmente para cargas hidráulicas maiores, com TAS > 6 kg/m2 , com qualidade dos drenados superiores para todas as cargas hidraúlicas; o método alternativo seria o mais indicado pois apresentou alta remoção com qualidade satisfatória. Somente o geotêxtil não – tecido GTNT600 não apresentou diferença estatística na MR seca independente da carga hidráulica e o método aplicado para seleção de polímeros. Em relação as eficiências, a EF (%) foi > 98% para os ensaios CP. Para a ESST (%) os valores foram > 96%. Maiores cargas hidráulicas obtiveram maiores eficiências de remoção de SST, independente da configuração do ensaio (SP e CP – cone e alternativo) com valores acima de 98%. CAPES: Código de financiamento 001

Funding Information: Open Access funding provided by Aalto University. This work was supported by Jane and Aatos Erkko foundation (3269-7422e). This study addresses one of the limiting factors for producing micro and nanofibrillated cellulose (MNFC)-containing papers: poor water removal properties. We focus on the sheet sealing phenomenon during dewatering. A modified dynamic drainage analyzer (DDA) is used to examine both multilayer and single layer forming of MNFC and pulp mixtures. It was found that a thin layer of pulp fibers on the exit layer with the grammage as low as 5 gsm was enough to significantly improve the dewatering of MNFC. For example, the dewatering rate of a furnish with 50% MNFC increased from 0.6 mL/s for a mixed system to 2 mL/s for multilayer system. However, the sheet sealing behavior was completely different when a lower proportion of MNFC was used. For the furnishes with less than 20% MNFC content, the mixed furnishes dewatered faster because the high amount of pulp fibers were able to prevent MNFC from enriching on the exit layer. Surprisingly, we found that very high final solids content (couch solids) could sometimes be achieved when MNFC was used. The highest solids contents achieved were 34 and 29% for the mixed systems. This compares to the 15–20% range typical of standard papermaking furnishes without MNFC. Overall, the results show that contrary to current thinking MNFC containing papers may lead, under some circumstances, to enhanced wire section dewatering.