Flocculation Aid Research Articles

Research the slurry thickening efficiency of aluminum companies in Vietnam using experimental settling column system

The thickening is the process of increasing the solid fraction in the slurry. The purpose of the process is to obtain a thicker sludge product and to obtain an overflow product with a minimum solid amount. The equipment used are traction thickener, cable thickener, caisson thickener, tray thickener, E-Cat thickener, lamella thickener, etc. This stage plays an essential role and greatly affects operations in mineral beneficiation factories. However, this is a problem for Aluminum companies in Vietnam because the amount of particles passing 1 mm is significantly higher than the design, leading to the overloading of thickeners. The overall productivity of the factories was affected and seriously reduced due to not being able to ensure the amount of feeding coarse particles and having to stop the operation to fix the problem. The requirement is to find and apply advanced technologies to improve the sedimentation process. This article presents the characteristics of bauxite slurry in Daknong and Lamdong companies. The amount of fine particles passing 0.02 mm reaches more than 62% (in the case of Daknong) and 72% (in the case of Lamdong) with the main minerals (gibbsite, goethite, kaolinite, ilmenite, etc.). On that basis, the survey was implemented to define the optimal type of flocculant aids (NALCO 85035 and HA - LB 080), flocculant dosage (40 grams/tons), and pH of the sludge (6.5 – 7). The obtained underflow product has a solid phase concentration of over 35% and the overflow has an amount of solid/water of less than 100 mg/l. Research was conducted on an experimental settling column system and it was recommended to pre-test a Lamella high-performance thickener for further research.

Treatment of effluents from Food Services Establishment (FSEs) by physico-chemical processes: a case study for Trinidad & Tobago

BackgroundEffluents from Food Services Establishments (FSEs) contain primarily Fats, Oil and Grease (FOG) which severely impact on sewers and the environment when released in high concentrations. In Trinidad & Tobago, it is estimated that approximately 231,304 kg/day of unaccounted for FOG bearing wastewaters from FSEs, are released into the environment with no viable treatment in the country. This research explored the optimization of physico-chemical processes for the treatment of FOGs for subsequent release into sewers.ResultsBench-scale studies analysed the characteristics of FSE’s effluents from three popular sources, conducted the treatment of these effluents using Jar Tests, and subsequently confirm results via a pilot plant study. Characterization showed the mean concentration of the parameters examined to be; FOG (511 mg/l ± 116 mg/l), Suspended Solids (446 mg/l ± 146 mg/l), Chemical Oxygen Demand (2229 mg/l ± 963 mg/l) and pH (6 ± 0.3). Jar Tests were conducted using Poly-aluminium Chloride (PACl) as coagulant, anionic and cationic polyelectrolytes as flocculant aids with suitable pH adjustments of samples to determine the isoelectric point for the coagulant. Effluent results showed FOG removal levels of 99.9% and final effluent concentration of 0.17 mg/l. This was attained using PACl concentration of 250 mg/l, a 0.1% low cationic polyelectrolyte (CP 1154) at 4 mg/l with the pH of sample adjusted to 8. The pilot plant achieved a 97.4% removal of FOG (residual of 16.8 mg/l) using the same coagulant dosing, and pH value, but increasing the strength of the flocculant aid to 0.1% medium cationic (CP1156) at 5 mg/l.ConclusionExperimentation showed high concentrations of emulsified FOG can be efficiently removed to levels below the permissible requirements (20 mg/l) for entry into sewer systems in Trinidad and Tobago using coagulation, flocculation and sedimentation techniques. Pilot scale study also revealed that a higher strength and/or dose of the cationic polyelectrolyte and increased times in primary and final tanks were required to attain the desired results as in the bench level study, where equipment limitations in the flocculation tank were faced. This is in alignment with theory where factors critical for agglomeration is equipment type and density charge. It is, concluded that the optimum combination of chemicals and the respective dosages attained at the bench level study should prove effective should the right equipment be made available.

Poly(acrylamide-co-sodium acrylate) Used as a Flocculation Aid Associated with Aluminum Polychloride in the Treatment of Low Turbidity Surface Water by Charge Neutralization

Poly(acrylamide-co-sodium acrylate) Used as a Flocculation Aid Associated with Aluminum Polychloride in the Treatment of Low Turbidity Surface Water by Charge Neutralization

Comparison analysis of cationic-polyacrylamide as flocculant aid in titanium salt coagulants

The combination of organic and inorganic coagulants is considered to be an effective strategy for Humic Acid (HA) removal. In this study, the performance of Titanium-based coagulants aided by Cationic-Polyacrylamide (CPAM) to HA molecules was compared. It was found that CPAM had a higher promotion effect in the TXC system. The reason for why CPAM was more suitable for the TXC system could be explained by analyzing Zeta potential, FTIR, and XPS. By comparing the coagulation mechanism of TiCl4 (TC) and Poly-Titanium Chloride (PTC), we found that complexation was the main mechanism of TC and PTC in acidic and neutral environments. The C-O-Ti Bond was formed by complexing the Ti-OH with the C-OH and -COOH functional groups of HA molecules. Sweeping was the most important removal mechanism of TXC in the neutral and alkaline environment, and CPAM bridged floc through hydrogen bond force for enhancing the sweeping effect. In addition, the role of CPAM in TXC system was further demonstrated by Zeta potential analysis. Both TC and PTC were positively charged in the measured pH range, so the removal of Humic acid was limited by increasing zeta potential. In both neutral and alkaline environments, TXC kept a negative surface charge and CPAM significantly enhanced the adsorption of HA on the TXC floc surface. This study provided clues for the interaction mechanism between titanium salt coagulants and HA, and it also provided a reference for the application of TXC coagulant combined with CPAM flocculant for the removal of HA molecules.

Suspended matter and heavy metals (Cu and Zn) removal from water by coagulation/flocculation process using a new Bio-flocculant: Lepidium sativum

BackgroundThe pollution of surface waters, due to the demographic and economic growth, requires very complex ways of treatment, where the world concern is focused on the substitution of synthetic products commonly used for the depollution of waters, by other natural elements, to ensure sustainable development. Moreover the main object of our study is to exploit natural supports, as bio polymers able to substitute the synthetic polymers used as aids of flocculation in the treatment of waters loaded with suspended solids (SS), and heavy metals, notably copper and zinc. For this purpose we used a new organic bio-flocculant, which we extracted from natural Lepidium sativum (LS) seeds, used for the first time as a flocculation aid to reduce the coagulant salt, improve the conglomerates of generated flocs, and ensure the removal of Copper and Zinc. Namely that the LS extract is known for its performance in various fields such as cosmetology, pharmacology and food products. Moreover, it does not present any danger for human health. MethodsOur preliminary flocculation tests were carried out on samples prepared at the laboratory level, and various operating parameters were studied such as: pH, nature and concentration of coagulant and bioflocculent content. After treatment, turbidity is monitored by nephelometric method, trace elements are analyzed by AAF and other spectroscopic methods are used (UV–Visible, SEM/EDS, XRD). Significant findsMucilage efficiency is studied in comparison with other products usually used in water treatment and depollution. The comparative study with a synthetic flocculant, anionic (Polyacrylamide: PAM), offers a good competitiveness with an important flocculation power. The association of the two stages of coagulation by the neutralizing salt, followed by flocculation using a new bioflocculent extracted from LS, gave significant results, in the abatement of SS in particular that based on marly limestone, where the turbidity passes from an average of 600 NTU to values close to 1NTU, as well as with the major elements in heavy metals (Copper and Zinc) of which a notable rate of elimination. The sludge generated after treatment using bioflocculent was found compact with less volume and it's same to the one generated from PAM synthesis flocculent. The first one was subjected to (SEM/EDS) and XRD analyses, all the chemical elements retained are detected after confirming that this sludge has less danger on the environment.

Geosmin and 2-methylisoborneol removal in drinking water treatment

Abstract Geosmin (GSM) and 2-methylisoborneol (2-MIB) are metabolites derived from cyanobacteria which produce taste and odor problems in drinking water treatment plants. Conventional treatment processes in water treatment are ineffective for the removal of 2-MIB/GSM. In this study, GSM and 2-MIB doses were applied to the raw water samples. Three powdered activated carbons (PAC), coconut shell, wood, and bituminous, and two oxidants, hydrogen peroxide and potassium permanganate, were evaluated. In addition, all the tests were made with and without flocculation aid (polyacrylamide). All the PACs evaluated showed better GSM and 2-MIB removals when conventional treatment was carried out with the addition of polyacrylamide as a flocculation aid. However, concentrations below the odor threshold were not reached. Regarding the oxidants, hydrogen peroxide presented the highest efficiency in eliminating GSM and 2-MIB when there is no presence of polyacrylamide.

Coagulation/flocculation-flotation harvest of Microcystis aeruginosa by cationic hydroxyethyl cellulose and Agrobacterium mucopolysaccharides

Efficient biocoagulants/bioflocculants are desired for removal of Microcystis aeruginosa, the dominant harmful bloom-forming cyanobacterium. Herein, we reported cationic hydroxyethyl cellulose (CHEC) inactivated M. aeruginosa cells after forming coagulates and floating-flocculated them with aid of Agrobacterium mucopolysaccharides (AMP) and surfactant. CHEC exhibited cyanocidal activity at 20mg/L, coagulating 85% of M. aeruginosa biomass within 9h and decreasing 41% of chlorophyll a after 72h. AMP acted as an adhesive flocculation aid that accelerated and strengthened the formation of flocs, approaching a maximum in 10min. Flocs of M. aeruginosa were floated after foaming with cocoamidopropyl betaine (CAB), which facilitated the subsequent filter harvest. 82% of M. aeruginosa biomass was suspended on water surface after treated with the coagulation/flocculation-flotation (CFF) agents containing CHEC (25mg/L), AMP (177mg/L) and CAB (0.1mg/L). All components in CFF agents at the applied concentrations did not inhibit acetylcholinesterase or Vibrio fischeri. Our findings provide new insights in developing bio-based materials for sustainable control of cyanobacterial blooms.

Study on application of fuzzy control model in phosphate removal system of sewage water

The precise input of flocculant and coagulant aid into phosphate wastewater is a key problem to degrade the phosphate content in sewage water and make the total phosphates and suspended pollutants in sewage water reach the discharged standard. In this paper, a new method combining fuzzy control technology with wastewater treatment control system was proposed to establish an automatic control system suitable for phosphates removal treatment. Based on experiment data and current experience, the membership function and fuzzy rules were set up, and the fuzzy control technology was obtained with simulation analysis, and the efficient treatment of sewage water was realized. It can be seen from the results that the fuzzy control technology can be applied to the phosphate removal control system for treating sewage water, and the standard of stable, accurate and efficient sewage treatment system can be established.

A comprehensive review on harvesting of microalgae using Polyacrylamide-Based Flocculants: Potentials and challenges

• Microalgae harvesting is a major bottleneck to microalgae-based biofuel production. • Flocculation is the most versatile, energy-efficient and cost-efficient harvesting process. • Polyacrylamides exhibit high harvesting performance at different operation scales. • Comprehensive analysis of polyacrylamide-microalgae flocculation was presented. • Properties of polyacrylamide and microalgae culture influence the flocculation process. Microalgae biomass is touted as a highly promising source of renewable third-generation biofuels that could enable a lucrative transition from conventional fossil fuels to more sustainable and environment-friendly energy alternatives. A significant limiting step for large-scale microalgae production and utilization is harvesting and dewatering the cultivated biomass, which comprise 20–30% of the total production expenses. Compared to traditional physical harvesting methods, coagulation-flocculation techniques using polyacrylamide-based flocculants have garnered attention as promising alternatives due to their high harvesting efficiencies, cost-effectiveness, convenience, and scalability. This paper delivers an up-to-date progress in the harvesting of microalgae suspensions using various polyacrylamide flocculants. For the first time, a comprehensive evaluation of existing harvesting studies for freshwater and marine microalgae species using polyacrylamide-based flocculants was conducted. The impact of polyacrylamide-based flocculant characteristics (e.g., charge type, charge density, polymer architecture, molecular weight) on flocculation efficiencies was examined. The effect of the culture medium properties (e.g., pH, salinity, microalgae species, microalgae growth phase, cell density, flocculation aids) on polyacrylamide-induced flocculation was also evaluated. Existing pilot-scale and large-scale polyacrylamide-based flocculation studies were explored. The review further identifies the research gaps, key challenges and future prospects for optimizing microalgae flocculation studies.

Biodegradable star-like polymer flocculants for rapid, efficient purification of water contaminated with industrial radionuclides

We report on the mechanisms and application of dextran-graft-polyacrylamide star-like polymers as efficient flocculation aids. Demonstrated in this paper is that these polymers form complexes with three common radionuclide contaminants: uranium, strontium, and cesium. Application of these polymers as flocculant aids together with inexpensive kaolinite-like materials allows fast and efficient purification of water. The methods presented here can be easily scaled up to industrial level decontamination of wastewater or used in large scale production of potable water.

Surface water treatment benefits from the presence of algae: Influence of algae on the coagulation behavior of polytitanium chloride

Titanium-based coagulation has proved to be effective for algae-laden micro-polluted water purification processes. However, the influence of algae inclusion in surface water treatment by titanium coagulation is barely reported. This study reports the influence of both Microcystis aeruginosa and Microcystis wesenbergii in surface water during polytitanium coagulation. Jar tests were performed to evaluate coagulation performance using both algae-free (controlled) and algae-laden water samples, and floc properties were studied using a laser diffraction particle size analyzer for online monitoring. Results show that polytitanium coagulation can be highly effective in algae separation, removing up to 98% from surface water. Additionally, the presence of algae enhanced organic matter removal by up to 30% compared to controlled water containing only organic matter. Polytitanium coagulation achieved significant removal of fluorescent organic materials and organic matter with a wide range of molecular weight distribution (693–4945 Da) even in the presence of algae species in surface water. The presence of algae cells and/or algal organic matter is likely to function as an additional coagulant or flocculation aid, assisting polytitanium coagulation through adsorption and bridging effects. Although the dominant coagulation mechanisms with polytitanium coagulant were influenced by the coagulant dosage and initial solution pH, algae species in surface water could enhance the charge neutralization capability of the polytitanium coagulant. Algae-rich flocs were also more prone to breakage with strength factors approximately 10% lower than those of algae-free flocs. Loose structure of the flocs will require careful handling of the flocs during coagulation-sedimentation-filtration processes.

Effect of PCC crystallization and morphology on flocculation with microfibrillated cellulose, on sheet densification and liquid absorption behavior

Composite sheets consisting of elongated and aggregated cationically charged precipitated calcium carbonate (PCC) and native microfibrillated cellulose (MFC) were prepared with a wet laying method. The furnishes were prepared with and without an anionic flocculating agent (polyacrylamide) in order to adjust the structure of the sheet. The samples were compressed (densified) in order to determine the particle and microfibrillated cellulose-PCC structure coalescence and densification, as well as its subsequent influence on liquid absorption behavior. The densification affected both the vertical and lateral distribution of PCC, but the flocculating agent enhanced the compression stability and stabilized the sheets against PCC material flow. The differences between the sheets made with and without the flocculation aid affected the absorption of an anionic dye-based fluid ink, which was evident as a higher print density and less print bleeding. The absorption behavior was dependent on the sheet structure, especially on the PCC distribution within the sheets. Finally, the role of MFC on floc structure and floc formation is discussed.Graphic abstract

Nitrogen-fixing cyanobacteria as a potential resource for efficient biodiesel production

The incessant utilization of non-renewable energy sources persistently pollutes the earth's atmosphere and thus requires the immediate substitution by renewable energy sources such as biofuel. In this study, several nitrogen-fixing cyanobacteria are screened for biodiesel production on the basis of biomass productivity, lipid productivity, lipid profiling, and harvesting potential. The assessment performed led to the identification of Nostoc sp. MCC41, a nitrogen ficxing cyanobacteria as promising species (0.39 day−1 specific growth rate, biomass productivity of 540 mg L−1 day−1, lipid productivity of 84 mg L−1 day−1 and 15.7% lipid content). A simple filtration experiment shows that almost 81% of the biomass of Nostoc sp. MCC41 is harvested without flocculation aid, while only 23–45% of the green algae (control) could be filtered. Based on the results, further optimization of Nostoc sp. MCC41 is carried out. The optimum light intensity to attain the highest lipid productivity is found to be 54 μmol photon m−2 s−1. Continuous illumination rather than other photoperiods is superior in terms of lipid productivity. Moreover, Nostoc sp. MCC41 could grow under mixotrophic conditions revealing the potential towards an organic carbon-rich wastewater treatment. At 0.5% glucose, the Nostoc sp. MCC41 exhibited nearly five-fold increase in biomass productivity when compared to the phototrophic conditions. Lipid profiling uncovered that Nostoc sp. MCC41 has a high concentration of palmitic acid, indicating its suitability for biodiesel. Given its easy mode of harvesting, ability to grow under mixotrophic condition, and ability to fix atmospheric nitrogen, Nostoc sp. MCC41 can be considered as a potential and eco-friendly resource for efficient biodiesel production.

Laboratory scale evaluation of coagulants for treatment of stormwater

The treatment effect and process characteristics of coagulation were investigated in semi-synthetic stormwater in laboratory-scale using jar tests. An initial screening of twelve coagulants and flocculant aids was carried out to find a selection of chemicals that efficiently reduced turbidity and suspended solids. Five coagulants were then further investigated with additional parameters measured (conductivity, alkalinity, and ζ-potential). The semi-synthetic stormwater was characterized by a high but variable, particle content, and low alkalinity. In the jar tests, a high treatment efficiency (>90 % reduction of both turbidity and suspended solids) was achieved for all coagulants. For very low alkalinity waters, the use of a biopolymer such as chitosan may be advantageous due to minimal alkalinity consumption. Based on the occurrence of charge reversal for all chemicals investigated, the mechanism for coagulation was likely charge neutralization. Treatment effect occurred in the ζ-potential span of -14 to +1 mV depending on the coagulant used. Initial turbidity and the ζ-potential are interesting parameter candidates for dosing control in stormwater treatment applications.

Application of Composite Pre-Polymerized Coagulants for the Treatment of High-Strength Industrial Wastewaters

The aim of this study was the investigation of alternative pre-polymerized coagulants for the treatment of high-strength industrial wastewaters, such as those created by tanneries, or by yeast production industries. The novel inorganic composite coagulant examined in this study (as well as variations of it) was denoted as PSiFAC1.5-10-15. The contribution of a typical polyelectrolyte to improve the effectiveness of the coagulation/flocculation (C/F) process was additionally studied, either by adding it separately (i.e., as a flocculant aid) or by co-polymerizing it within the structure of inorganic coagulant (denoted as PAPEFAC1.5-10-15). It was found that the PSiFAC1.5:10:15 coagulant, either with or without the addition of polyelectrolyte, can provide better efficiency for the C/F process than the conventional coagulants. For example, the addition of 80 mg Al/L in yeast production wastewater samples resulted in a 56% reduction of COD, 40% of turbidity, and 43% of phosphates, regarding the pre-treated anaerobically wastewater samples and reduced by an extra 22%, 14%, and 38% for the pre-treated anaerobically plus aerobically wastewater samples, respectively. The residual aluminum concentration in the treated wastewaters was found to be below the legislation limit of 200 μg Al/L. The characterization of coagulants showed the relatively higher Al13 content of 51% and 43% for the cases of PSiFAC1.5-10-15 and PAPEFAC1.5-10-15, respectively, accompanied by the high zeta-potential measurements (50.5 and 39.5 mV).

Enhanced Microalgal Harvesting Using Microalgae-Derived Extracellular Polymeric Substance as Flocculation Aid

Coagulation-based harvesting has been widely used in microalgal biomass harvesting. However, the coagulant contamination in the harvested biomass may negatively affect the applications in feedstock...

Effects of Flocculant, Surfactant, Coagulant, and Filter Aid on Efficiency of Filtration Processing of Copper Concentrate: Mechanism and Optimization

In the recent decades, water scarcity has become a major challenge for many reasons, especially the inadequate use of water resources. The mineral processing plant is among the most important water-consuming industries. Filtration, as one of the important processes in water recovery, is a process in which the solid-suspended particles are removed from the liquid. In the present work, the effect of the additives affecting the filtration process upon the responses including the resistance to filter cloth (R), specific cake resistance (α), moisture content, water recovery rate, and cake formation rate by the vacuum top-feed method is investigated. The experiments are performed by two methodologies: one-factor-at-a-time and statistical analysis. The additives are the flocculant, coagulant, surfactant, and filter aid. According to the one-factor-at-a-time methodology, the optimal type and dosage of the variables are as follow: flocculant A25 with a concentration of 15 g/L, perlite as the filter aid with an amount of 2.5%, surfactant cop 20-101 with a concentration of 3 cc/L, and the coagulant CaCl2.2H­2O with a concentration of 2.5 g/L. The usage of the flocculant, surfactant, and filter aid at the same time is also statistically analyzed with the aim of maximizing the cake formation rate and minimizing the moisture content of the filter cake. Under the optimal conditions and taking into account 11.68 g/t of the flocculant A25, 3.8% of perlite as the filter aid, and2.92 cc/L of the surfactant cop 20-101, the cake formation rate and the moisture content were obtained to be 0.297 mm/s and 12.7 %, respectively.

Nutrient Reduction of Dairy Manure Through Solid-Liquid Separation with Flocculation and Subsequent Microalgal Treatment.

High concentrations of dairy operations in Southern Idaho have brought up big challenges for proper manure management to alleviate the eutrophication stress. In order to explore more technologies confronting the high nutrient load in dairy manure, a sequential process combining enhanced solid-liquid separation through flocculation-centrifuge and the subsequent microalgal growth in the liquid part was studied in this study. Solid-liquid separation by flocculation-centrifuge process, using a natural flocculant chitosan and a flocculation aid kaolin, was optimized through response surface methodology (RSM) technique using central composite design (CCD) method. Under the optimal flocculation-centrifuge pretreatment, i.e., the maximal total suspended solid (turbidity) removal group, turbidity, COD, TKN, and TP have been removed by 92.7%, 72.6%, 58.7%, and 43.0%, respectively. Applying 2-fold dilution, the supernatant from this treatment was further used for microalgae Chlorella vulgaris cultivation. COD, TKN, and TP were further reduced by 82.2%, 90.1%, and 83.4%, respectively. Turbidity was largely removed from the original dairy manure, providing a relatively clear solution that became suitable for photo-mixotrophic culture of microalgae.

Evaluación de FeCl3 y PAC para la potabilización de agua con alto contenido de color y baja turbiedad

La fuente de agua para abastecimiento proveniente del páramo se caracteriza por su alto contenido de color y baja turbiedad, lo que representa un inconveniente por considerar en la mayoría de plantas potabilizadoras. Internacionalmente se han realizado estudios al respecto, pero en general, las soluciones que se plantearon fueron costosas y no se adaptaron totalmente a este tipo de fuentes colombianas (país con escasas investigaciones). El propósito de este trabajo fue la evaluación de FeCl3 como coagulante primario y PAC (Policloruro de aluminio) como auxiliar a escala de laboratorio para la potabilización de agua cruda con elevado color y baja turbiedad. Se realizó el ensayo de jarras con FeCl3, PAC, FeCl3 + PAC como ayudante de coagulación, y FeCl3 + PAC como ayudante de floculación. Los parámetros evaluados fueron pH, color y turbiedad, antes y después de los tratamientos; con un rango de dosis para FeCl3 entre 36-42 mg/L y para PAC entre 0,2-0,5 mg/L. Los resultados revelaron que en términos de eliminación de color la combinación FeCl3 + PAC como ayudante de coagulación presentó la mayor eficiencia entre los tratamientos estudiados (86,9 %), mientras que para remoción de turbiedad el rendimiento alcanzó 80,2 %. De igual manera, se demostró que dicha alternativa representó un ahorro en costos, si se compara con PAC como único coagulante (entre 25,5-34,2 %), dependiendo del caudal tratado. En cuanto al cumplimiento de la normatividad vigente colombiana, se cumplió con los valores máximos permisibles (Color = 15 UPC, Turbiedad = 2 UNT), con excepción del pH que debió estar entre 6,5-9,0, y que debió ser estabilizado antes de enviar el agua tratada por la red de distribución.

Cationic cellulose nanofibers as sustainable flocculant and retention aid for reconstituted tobacco sheet with high performance

The study that cationic cellulose nanofibers (CCNF) acts as sustainable flocculant and retention aid of precipitated calcium carbonate (PCC) for the preparation of reconstituted tobacco sheet (RTS) was carried out, thanks to the properties of CCNF. In this work, the enhanced flocculation, reflocculation and size properties of PCC flocs induced by CCNF were investigated via a focused beam reflectance measurement (FBRM) system. The physical properties of RTS such as bulk and air permeability etc. were also studied. The results indicated that CCNF could distinctly improve the flocculation and reflocculation properties of PCC with a desirable chord length in the tobacco slurry, and that the PCC retention was also increased with CCNF addition along with a slight decrease of tensile strength of RTS. The mechanisms of flocculation and reflocculation, as well as the reasons of enhanced bulk and air permeability properties ascribed to CCNF were also demonstrated.