Tannin-based Coagulant Research Articles

Comparative ecotoxicological evaluation of tannin coagulants from black wattle and ferrous aluminum sulfate in the treatment of slaughterhouse effluent

Ecotoxicological assessments are crucial for environmental monitoring as they can pre-dict the adverse effects of ecotoxins, such as coagulants, on the ecosystems using contamination bioindicators. This study evaluated the ecotoxicity of two types of coagulants, an inorganic coagulant, ferrous aluminum sulfate (SF), and a biocoagulant based on tannins extracted from black wattle, used in the treatment of cattle slaughterhouse effluents. The planaria Girardia tigrina, which is used as a bioindicator of toxicity in freshwater ecosystems, was used as the test organism for this study. To select the appropriate tannin coagulant for the effluent under study, two types of biocoagulants were investigated: Tanfloc SG (SG) and Tanfloc MTH (MTH), with SG coagulant showing better performance (98.5 % turbidity removal). In the ecotoxicological test, SG and SF coagulants were compared. Both the tannin-based coagulant SG and the inorganic SF were effi-cient for the treatment of the evaluated effluent, yet their lethal concentrations (LC50 - 96h) with regard to G. tigrina was 32.24 % and 42.24 %, respectively. Thus, our results suggest that the effluent treated with the tannin-based coagulant SG showed greater toxicity to G. tigrina than the inorganic coagulant ferrous aluminum sulfate.

Application of a tannin-based coagulant for harvesting Parachlorella kessleri microalgae cultivated in chicken meat thermal processing wastewater

Application of a tannin-based coagulant for harvesting Parachlorella kessleri microalgae cultivated in chicken meat thermal processing wastewater

Study of the Sedimentation Parameters of an Iron Ore Tailing from Fundão Dam Using a Tannin-Based Coagulant

From the rupture of the Fundão dam in Mariana–MG, there are tailings still present at the bottom of the plant that must be recovered. The flocculation followed by sedimentation operation can be applied as a unit operation in this recovering process. Instead of using conventional inorganic coagulants, bio-based coagulants offer some advantages, due to their low toxicity and biodegradability. Nonetheless, the use of bio-based coagulants in the mining industry is not established yet, due to the complex parameters that must be taken in consideration. This study analyzes the influence of the pH and flocculant concentration, which are the variables of the 22 full factorial design. The pH value for the batch sedimentation process was defined ranging from 5 to 9. Tanfloc, a tannin-based coagulant, was used as a coagulant agent. The results indicate a strong dependence on the coagulant concentration, and a recommended 15 g/L dosage with pH varying from 6 to 8. From batch sedimentation, it was possible to determine an exponential model for the sedimentation with an excellent fitting (R2 = 0.997). The sedimentation efficiency calculated is 65.6%. These results confirm the potential use of bio-based materials in mining tailing treatments. In addition, they can be used in equipment sizing and simulations of the sedimentation operation.

Assessment of natural tannin-based coagulant for effective ultrafiltration (UF) of UASB effluent: Fouling mechanisms, pollutant removal and water reclamation feasibility

In this work, tannin coagulant (TANm) was applied at different dosages and compared with a PACl for UASB effluent filterability enhancement during membrane ultrafiltration. The results showed that TANm exhibited the greatest potential to improve UASB effluent filterability. Flux decay, total fouling resistance, and specific cake layer resistance were all reduced by both coagulants. However, the highest flux (55%) and fouling resistance reduction (70%) were obtained with 40 mg.L−1 of TANm, which was caused by an increase in particles larger than 200 μm, facilitating its removal by cross-flow filtration. Protein and carbohydrate reduction in the membrane was only observed at 25 mg.L−1 for both coagulants, with a higher influence of proteins in strongly/very strongly bound for all samples. In addition, fouling irreversibility increases, with a strong correlation between TANm dosage and Rirr and complete and intermediate pore blocking pointed as the main mechanisms responsible for irreversibility for both coagulants. Based on these and other findings, the mechanisms of the fouling layer adhered to the membrane with coagulants included the formation of complexes with proteins that were more strongly adhered (related to UASB effluent zeta potential increase), the density of the cake layer due to the presence of compact aggregates, and action of the coagulants themselves as foulants. Lastly, the economic evaluation revealed that the system without coagulant would have a lower total cost, but payback showed that the application of TANm has a lower investment time of return due to a lesser CAPEX.

Microwave-Assisted Extraction of Polyphenols from Eucalyptus Bark—A First Step for a Green Production of Tannin-Based Coagulants

Tannins are natural polyphenolic compounds widely found in plants. The production of natural coagulants for water treatment is one of their new applications. Polyphenols extraction is the first step for synthesizing tannin-based coagulants. Eucalyptus globulus bark (EGB), an abundant by-product of the pulp and paper industry, usually applied as fuel for energy production, was used in this work as a tannin source. The extraction of polyphenols from EGB was studied using water as a solvent. Extraction assays employing different extraction techniques were conducted. Microwave-assisted extraction showed superior performance and was further optimized. The influence of irradiation time, water-to-bark ratio, and temperature were evaluated using Response Surface Methodology. The extraction yield and the total phenolic content of the extract were modeled as function of the extraction conditions. The overall best conditions that maximize both responses were obtained through multi-response optimization. Optimized values (15% of extraction yield and a phenolic content of 354 mg of gallic acid equivalents per gram of extract) were predicted for an extraction time of 15 s, a liquid-to-solid ratio of 48.5 mL/g, and 141 °C. The extract generated under these conditions presented a condensed tannin content of 645 mg/g, expressed in terms of catechin equivalents. EGB presented good tannin-extractable contents to produce natural coagulants.

Effects of tree harvesting time and tannin cold/hot-water extraction procedures on the performance of spruce tannin biocoagulant for water treatment

This study investigated the effect of seasonal variation (i.e. winter and summer) on tannin extracts from spruce bark as biocoagulants for water treatment applications. Tannins were extracted through three different water extraction procedures: cold-water extraction (21 °C), cold-water plus hot-water extraction (85 °C) and direct hot-water extraction (85 °C). 1H nuclear magnetic resonance spectra showed that the cold-water plus hot-water extractions possessed the highest proportion of phenols. Electrospray ionization-mass spectrometry indicated that a preliminary cold-water extraction sufficiently reduced the non-phenolic constituents (monosaccharides and sugars) from the winter bark in the cold-water plus hot-water extraction but not from the summer bark. The synthesis of tannin-based coagulants was performed through the Mannich reaction using formaldehyde and ethanolamine. Coagulants with the highest charge densities (3.379 ± 0.012 meq/g) were produced with tannin extracts obtained from the winter bark cold-water plus hot-water extractions. Water treatment experiments with the coagulants from the winter and summer bark cold-water plus hot-water extractions demonstrated that they were effective for particle settling. The study proved that the tree harvesting season and extraction procedure play a critical role in obtaining high-quality spruce tannin for the synthesization of tannin-based biocoagulants that provide better coagulative performance.

Application of tannin-based coagulant for high-range turbidity surface water clarification

Abstract This study aimed to evaluate the performance of a tannin-based coagulant in clarifying drinking water from a high-range turbidity river and characterizing the sludge. Tanfloc MTH product was selected for this investigation. The study site was surface water located in southern Brazil (Caveiras River, Brazil). Samples were collected just before the Parshall flume in the municipal water treatment plant in Lages (Brazil) for nine months, at least once a week. Jar testing evaluated turbidity removal, alkalinity consumption, optimal coagulant dosage, and settling velocity. After flocculation and settling, the sludge generated from the jar test was submitted to metal and thermogravimetric analyses. The use of tannin reduced the average water turbidity from 26.1 ± 56.1 to 0.94 ± 0.26 NTU, apparent color from 145 ± 190 to 3 ± 3 Pt-Co, and there was no variation in the pH. Additionally, the settling velocity of the flocs reached a maximum turbidity removal at 3.5 cm·min−1. Furthermore, the metal concentrations in the sludge showed a majority of aluminum and iron, and thermogravimetric analysis revealed 64% weight loss. In conclusion, Tanfloc presented the potential to be used in surface water clarification from the Caveiras river, and the extensive turbidity range observed during this study did not affect the operational stability.

Characterization of a byproduct generated by the treatment of water from a biofloc technology system using a plant tannin-based coagulant

The aim of the present study was to characterize the sludge generated by the treatment of water from a biofloc technology (BFT) system using a tannin-based coagulant. Bromatological, thermogravimetric and microbiological analyses were performed. Toxicity was investigated using lettuce seeds (Lactuca sativa) and onion roots (Allium cepa). Water samples were obtained from a rearing of Oreochromis niloticus in BFT system. The residue generated by the treatment of water with a tannin-based coagulant was considered in this study. The bromatological characterization revealed that the sludge had an average of 14.37% crude protein, 50.77% mineral fraction and 0.21% ether extract. Treatment with tannin did not cause an increase in the sludge total phenol content compared to that generated by bioflocs alone. However, the sludge generated by the treatment with tannin-based coagulant caused the complete inhibition of lettuce seed germination and a significant reduction in the mitotic index of onion roots, which may be due to the high dose of tannin-based coagulant applied to promote optimal water treatment conditions to obtain the sludge. In vivo tests are needed to identify the response of animals and indicate the best species for the incorporation of the sludge into the diet.

Using tannin-based coagulant in the control of solids in a biofloc cultivation system: evaluation of treatment performance and phytotoxicity

Using tannin-based coagulant in the control of solids in a biofloc cultivation system: evaluation of treatment performance and phytotoxicity

Use of tannin-based coagulant and chlorine dioxide in treating brewing water: reduction of trihalomethanes and impact on physicochemical and sensory quality

This study aimed to evaluate an alternative to reduce trihalomethane (THM) formation in brewing water. THM affects the organoleptic properties of water and, consequently, the produced beer. Water treatment based on common chemicals such as alum and free chlorine could potentially form THM. Therefore, we studied the replacement of chemicals used in water treatment: aluminum sulfate by a tannin-based coagulant and sodium hypochlorite by chlorine dioxide. Experimentally, jar tests were conducted, and the role of coagulants and oxidizing agents was evaluated for: the removal of apparent color, turbidity, natural organic matter (NOM) and microorganisms; the formation of trihalomethanes (THM); and the sensory quality of the water. Using tannin-based coagulant with chlorine dioxide was associated with the lowest THM in treated water (1.7 µg/L) and higher satisfaction in the sensory analysis. However, using these chemicals make the water treatment more expensive than the current strategy. Overall, using the tannin-based coagulant and chlorine dioxide treatment is an alternative to produce water with a lower THM concentration, better physical-chemical, and sensory quality. These findings motivate further brewing experiments and a deeper economics evaluation considering the process’s sustainability.

Biologia Futura: treatment of wastewater and water using tannin-based coagulants.

Industrialization and urbanization are mainly responsible for environmental pollution generating enormous amount of wastewater which needs to be treated. Wastewaters from various sources are toxic to humans and livestock, as well as posing environmental risks. Various treatment approaches have been used for the elimination of contaminants from water and wastewater. Coagulation/flocculation processes are the most commonly used techniques in water treatment for improving the condition of turbid water and removing suspended particles by destabilization and the creation of larger, heavier flocs that aid in sedimentation. Flocculants, both organic and inorganic, have long been used in wastewater treatment. The use of natural coagulants/flocculants for water and wastewater treatment has become essential due to the health risks associated with chemical flocculants. Tannin, a natural coagulant, has been suggested as substitute of chemical coagulants. Tannins are present in the leaves, fruits, barks, roots, and wood of trees as a secondary metabolite. Tannin-based coagulants derived from a variety of plant sources have been successfully used in the treatment of water and wastewater. This review summarises the current status and strategies on applications of tannin-based coagulants exploiting the eco-friendly green materials in water and wastewater remediation for the sake of pollution free environment.

Decolorization of a Simulated Reactive Textile Dyeing Effluent using a Plant-derived Coagulant

The ability of a commercial tannin-based coagulant on the decolorization of a simulated textile effluent containing a reactive dye was studied in batch mode. For comparison, two conventional chemical coagulants (aluminum sulfate and Rifloc 6548-organic coagulant) were also tested. Preliminary assays suggested a higher performance of Tanfloc SG and Rifloc coagulants over the metal salt. Optimization assays conducted for Tanfloc SG, indicated a maximum color removal of 86.4%, recorded at a coagulant dosage of 240 mg/L and at pH 7. A decolorization efficiency of 42.4% was found for the optimized dosage of 144 mg/L at pH 9. At this condition, the treatment cost using Tanfloc was estimated as 0.21 EUR/m3, around twice the Rifloc when used at 96 mg/L, generating 81% of treatment efficiency. Rifloc outperformed Tanfloc, and its use also seemed to be more economical but may have negative impacts on the environment. However, Tanfloc still showed promising results and presented a better performance in terms of sedimentation velocity and floc size.

The Effect of Extract Tannins from Spent Coffee Ground on Waste Water Treatment

Green extraction processes to obtain high value bioactive compounds from raw natural materials and wastes has gained attention the past few years. In the present study, we investigated a Natural Deep Eutectic Solvent derived from two natural products, namely choline chloride and glucose as a potential solvent for the extraction of tannin compounds from spent coffee ground(SCG). A tannin was used as coagulant with the Poly aluminium chloride(PAC) as flocculant. Initially, jar test experiments were conducted with a varying dosage of coagulant and initial pH. Next, tests were carried out with different values of PAC dosage, flocculation time as well as sedimentation time to find out the optimum condition for colour removal. The supernatant layer of treated leachate from each test was analysed for colour, pH and conductivity. At optimum leachate pH of 5, experiments with 3 minutes flocculation time and sedimentation time of 10 minutes resulted in the highest colour removal (81.8%) at coagulant dosage of 100 mg/L, with 1 mg/L PAC being added. Coagulation flocculation system of as tannin-based coagulant with PAC as flocculant showed the promising result in decolourisation of wastewater.

Sustainable tannin-based coagulants synthesized through Mannich reaction using melamine as an amine source for water treatment applications

This study explored the potential of melamine, as the nitrogenating source for the cationization of pulverized quebracho and spruce tannins. The influence of modification conditions on the properties of the coagulants was studied by varying the formaldehyde and melamine ratios with different activation times and temperatures. Based on considerations of charge density and shelf life, the most viable modifications were established as coagulants synthesized with a 1:0.52 formaldehyde to melamine molar ratio at 70 °C. At optimal conditions, the charge density of the quebracho and spruce coagulants was 2.22 meq/g and 1.04 meq/g, respectively, and the residual formaldehyde content in the coagulants was low. The developed synthesis of this study demonstrated a clear advantage over previous methods due to the rapid modification step. X-ray photoelectron spectroscopy (XPS) confirmed the emergence of an amine which signifies a successful Mannich reaction in the coagulant. Although optimal modification conditions for the coagulants were established at 70 °C (5-min activation time), the average molecular weight could not be determined for these conditions. Nevertheless, electrospray ionization mass spectrometry (ESI-MS) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry measurements revealed that the tannin-based coagulants obtained at lower temperatures (23 °C and 45 °C) possessed low average molecular weight (approx. 800–900 Da). Furthermore, ESI-MS and MALDI-TOF spectra showed that the Mannich modification resulted in the depolymerisation of the quebracho tannin, leading to a reduction in units of higher mass fractions in the synthesized coagulant, which contrasted with the spruce tannin. Jar test experiments with surface and industrial process waters demonstrated that the tannin coagulants enhanced particle settling effectively.

Decolourisation of Sewage using Commercial Tannin-Based Coagulant

In this work, the effectiveness of removing colour and total suspended solid (TSS) from complex organic particulate artificial sewage (COPAS) via the coagulation process was studied. Organo-floc (OF), a tannin-based coagulant derived from the plant was used as a coagulant. OF was applied in a jar test experiment at the various dosages at 57 rpm for 5 min, and 30 min sedimentation time to find out the optimum dosage for colour and TSS removal. Zeta potential, pH and conductivity were also analysed. Experiment with tannin dosage of 125 ppm resulted in the highest colour and TSS removal of 94% and 79%, respectively. Organo-floc showed promising results in decolourisation and TSS removal from artificial sewage.

Tannin-based coagulant for harvesting microalgae cultivated in wastewater: Efficiency, floc morphology and products characterization

Tannin-based coagulants (TBCs) have the potential to be used to harvest microalgae cultivated at wastewater treatment plants. Their use would address the circular economy associated with the production of low-toxicity biomass and supernatant. Studies in this field are still scarce, and substantial gaps exist in the definitions of the flocculation process parameters. In this context, the objective of this work was to evaluate TBC performance as a natural coagulant for harvesting microalgae biomass grown in sanitary effluent digested in an up flow biofilter, as well establishing a path to enable recovery and reuse of wastewater nutrients. Classical removal techniques combined with image analysis and light scattering-based equipment were used to evaluate the coagulant performance, recovery efficiency, floc strength, and floc recovery compared to aluminum sulfate (AS). The results showed that TBC was able to efficiently harvest algal biomass from the effluent, achieving color, turbidity, and optical density (OD) removal efficiencies greater than 90% with only 5 min of sedimentation. The optimal harvesting dosage was 100 mg·L−1 for TBC and 75 mg·L−1 for AS. TBC presented the advantage of harvesting biomass without changing the pH of the medium and was also able to present satisfactory removal of the analyzed parameters (color, turbidity and OD) at pH values of 5.0, 7.0, and 8.5. In addition, TBC produced stronger flocs than AS, showing a better ability to resist breakage upon sudden shear rate variations. TBC produced macronutrient-rich biomass and supernatant that was similar to that produced with AS.

Synthesis of hydrochars derived from industrial laundry sludge and its application in the removal of cationic dye

The textile industry generates large amounts of effluents, often treated by coagulation/flocculation. The tannin-based coagulants produce a high-quality treated effluent and a more biodegradable sludge. Efforts have been made to reuse the sludge, however, the synthesis of hydrochars and activated hydrochars from this residue was never evaluated before. Therefore, this study aimed to produce a novel sludge-based adsorbent, through hydrothermal carbonization (HTC) and KHCO₃ activation, from real laundry wastewater treated with tannin (Tanfloc SG), in order to remove methylene blue (MB) from aqueous solutions. Tanfloc SG coagulant was more effective to reduce color and turbidity than chemical oxygen demand. The best coagulant concentration (140 mg L−1) was selected to produce sludge, the hydrochar (HC-S), and activated hydrochar (AHC-S). The characterization demonstrated that activation volatilized the organic matter, leaving coke and inorganic solids. However, despite the lower carbon content, AHC-S presented a notorious surface area (3005.57 m² g−1). Minerals were presented in the adsorbents and AHC-S showed graphene-like layers. Regarding MB adsorption, pseudo-second-order and Langmuir models fitted kinetic and equilibrium data, respectively. HC-S and AHC-S obtained qmax of 69.77 and 808.83 mg g−1, respectively, and the latter was higher than other activated hydrochars, demonstrating the potential of the adsorbent.

Combined system for wastewater treatment: ozonization and coagulation via tannin-based agent for harvesting microalgae by dissolved air flotation

ABSTRACT This study evaluated the performance of urban wastewater treatment in pilot-plant by an integrated system consisting of anaerobic reactor, microalgae cultivation, Venturi tube ozone recirculation, coagulation/flocculation with tannin-based agent natural coagulant, and dissolved air flotation (DAF). Ozone concentrations (without ozone, 0.13 and 0.25 mg O3/mg of biomass) and tannin dosages (65, 85 and 105 mg/L) were evaluated regarding microalgae separation and their influences on wastewater treatment performance. During the experiments, it was verified that the treatment efficiency increased when ozone was applied and with higher tannin dosages. The best results were found with 0.13 mg O3/mg of biomass and 105 mg/L of tannin, obtaining excellent removal of turbidity removal (99.4%), apparent colour at 420 nm (94.5%), TN (83.2%), N-NH3 (100%), TOC (86.8%), BOD5 (86.5%) and COD (100%), 47.6% reduction in electric conductivity, 46.1% in TDS, 66.4% TP removal for the integrated system and 84% microalgae biomass recovery were obtained. Our results showed that the system proved to be a viable alternative for the treatment of urban wastewater and the recovery of microalgae through the insertion of ozone via Venturi tube combined with tannin-based agent.

Effect of pre-treatment with a tannin-based coagulant and flocculant on a biofilm bacterial community and the nitrification process in a municipal wastewater biofilm treatment unit

Tanfloc, a natural tannin-based coagulant and flocculant, was used in this study as a pre-treatment agent for a biofilm unit that was used to treat municipal wastewater. The point of interest in this study was the effect of the extended use of Tanfloc (around 2 months) on the biofilm bacterial community. Two identical bench-scale aeration tanks were run in parallel, one of them treating settled wastewater, and the other pre-treated (flocculated/settled) wastewater using Tanfloc. The results showing the effect of Tanfloc was very apparent on the characteristics of the wastewater. At a hydraulic retention time of 4 h, the relatively short retention time was not enough to achieve any noticeable removal of ammonia without Tanfloc. In contrast, the 4 h retention time was sufficient to achieve around 70 % removal of ammonia when Tanfloc was used. This improvement in the nitrification process was attributed to the bacterial community of the biofilm as a consequence of Tanfloc use. A bacterial 16S rRNA analysis of the biofilm showed a significant increase in the percentage of ammonia-oxidizing bacteria (3.33 %) and nitrite-oxidizing bacteria (7.8 %) in the experiment using Tanfloc, compared to only 0.073 % and 0.19 % respectively, in the experiment without Tanfloc.

Treatment of wastewater from a gas station by tannin-based coagulant and the sludge characteristics

Treatment of wastewater from a gas station by tannin-based coagulant and the sludge characteristics