WATER TREATMENT AND ITS ALTERNATIVE METHODOLOGIES: USE OF NATURAL COAGULANTS AND HELICALLY COILED TUBE FLOCCULATORS FOR WATER CLARIFICATION

Objective: This study aims to explore alternative and innovative methods for water clarification, with an emphasis on the application of natural coagulants and Helically Coiled Tube Flocculators (HCTFs) as viable and effective solutions compared to conventional methods. Theoretical Framework: The theoretical framework is grounded in the fundamental principles of water clarification and traditional technologies, highlighting the limitations of conventional chemical coagulants and their implications for public health and the environment. The research reviews studies that demonstrate the environmental and public health benefits of natural coagulants. Method: The adopted methodology includes a literature review on natural coagulants and HCTFs, followed by a laboratory-scale experiment. Natural coagulants were used in conjunction with HCTFs in a hydraulic system operating in batch mode to evaluate the efficiency of turbidity removal. Results and Discussion: The results demonstrated a significant efficiency in turbidity removal, achieving 95% within a flocculation time of less than 2 minutes. The discussion contextualizes these findings within the theoretical framework, highlighting the advantages of natural coagulants and HCTFs compared to traditional methods. Research Implications: The implications of this research suggest that combining natural coagulants with HCTFs can be applied on a large scale to enhance the efficiency and sustainability of water treatment systems, benefiting both public health and the environment. Originality/Value: This study contributes to the literature by proposing the combination of HCTFs with natural coagulants, offering an effective alternative to conventional water clarification methods and positively impacting environmental sustainability and public health.


INTRODUCTION
Freshwater consumption has increased sixfold in the last century and continues to grow at a rate of 1% per year, a result of population growth, economic development and changes in consumption patterns (UNESCO, 2021).This increases river pollution and, consequently, reduces water quality.Also according to UNESCO (2021), approximately 80% of industrial and municipal effluents are released into the environment without any prior treatment, causing harmful effects on human health and ecosystems.
Water treatment aims to improve the characteristics of raw water and varies according to its destination and quality.Water quality is defined by its physical, chemical and biological characteristics.
It should be noted that water for human consumption is drinking water intended for ingestion, food preparation and personal hygiene, regardless of its origin; and drinking water is water that does not pose any risk to human health.
The most widespread technology in Brazil for water treatment is called conventional treatment, which has three phases: clarification, filtration and disinfection.In the clarification phase, suspended solids and part of the dissolved solids are removed; In filtration, dissolved solids, microorganisms such as bacteria, cysts and protozoan oocysts are removed.Disinfection is the process designed to inactivate pathogenic microorganisms that are still present in the water (Heller & Pádua, 2010).
In this context, the present article aims to carry out a comprehensive review of the literature on alternative water clarification processes, with an emphasis on analyzing the effectiveness of natural coagulants and the use of Helical Tubular Flocculators ( FTHs ) coupled to conventional decantation systems, validating theoretically and experimentally its viability as an efficient, low-cost and environmentally sustainable solution for water treatment.

COAGULATION, FLOCULATION AND DECANTATION
The main objective of coagulation and flocculation is to increase the sedimentation rate of solids through the addition of coagulant ( Libânio , 2010).In the coagulation stage, suspended and colloidal particles are destabilized, generally by the use of aluminum or iron salts, due to the individual or combined action of sweeping mechanisms, compression of the double layer, adsorption and neutralization of charges, as well as the formation of bridges.( Libânio , 2010;Di Bernardo et al ., 2017).In water treatment plants, the coagulation process occurs in the rapid mixing unit, where there is an intense mixture between the coagulant and the raw water (Richter, 2009;Libânio , 2010).
Flocculation is a process made up of a set of physical phenomena with the aim of reducing the amount of suspended and colloidal particles present in water ( Libânio , 2010).This reduction occurs when particles destabilized or coagulated by the action of the coagulant come together to form larger flakes, which will be later removed by sedimentation, flotation or filtration (Richter, 2009;Libânio , 2010).According to NBR 12216 (1992), flocculators are the units used to promote the agglutination of particles formed in rapid mixing.There are two types of flocculators : (a) mechanical, which use mechanical devices (palettes, turbines or propellers) to agitate the liquid mass; (b) hydraulic, which take advantage of the hydraulic energy of water movement to promote agitation in the liquid mass and, consequently, the formation of flakes (Richter, 2009;Libânio , 2010).In addition to these conventional models, an unconventional model of flocculation unit has been studied, called a helical tubular flocculator , which consists of flexible tubing wound helically around a rigid cylinder ( Carissimi , 2003;Pelissari , 2006;Silva, 2007;Oliveira , 2008;Sartori, 2015 ; The interaction of particles with water occurs through the action of three mechanisms: 5 movement ( Libânio , 2010).
Decantation is the last stage of clarification, in which the flakes previously formed by the action of gravity settle ( Libânio , 2010).Generally, water contains particles in a colloidal state or in solution that are not removed by simple sedimentation, which makes it necessary to add a coagulant to form flocs that settle more easily (Richter, 2009).
The units in which this process occurs are called settling tanks or decanters (Richter, 2009).NBR 12216 (1992) defines decanters as units designed to remove particles present in water, through the action of gravity.These clarifiers can be of three types: horizontal flow clarifiers, high rate clarifiers and sludge mantle clarifiers -floc clarifiers ( Libânio , 2010).
Horizontal flow decanters are the most used in Brazil, generally, they have a rectangular shape in treatment stations, as it is easier to adapt to the layout of the plants and with the prospect of using the walls to build flocculators and filters ( Libânio , 2010) .
When sizing horizontal flow decanters, there must be a convenient relationship between length (L) and width (B) (Richter, 2009).According to Di Bernardo et al . (2017), the limits for the length (L) and width (B) ratio are 2 ≤ L/B ≥ 5, generally around 3; Furthermore, the length (L) and depth (H) ratio must be in the range of 2 ≤ L/H ≥ 25.According to Funasa (2014), for decantation to be efficient, the decanter must remove at least 90 .0% of the turbidity present in raw water, as filtration efficiency is directly related to the quality of decantation.

COAGULANTS IN WATER TREATMENT
A coagulant is any agent that reacts with colloidal particles, destabilizing them and reducing the forces that keep them separate, usually a chemical product (Richter, 2009).
Aluminum sulfate stands out as the most used chemical coagulant in Brazilian ETAs , due to its high efficiency and low cost, but for more remote areas, it becomes expensive due to the cost of transportation ( Lo Monaco et al ., 2012).
The possible environmental impacts caused by the use of aluminum-based coagulants are constantly discussed (Lima Júnior & Abreu, 2018).Among them are: the very high production of non-biodegradable and toxic sludge, which requires treatment before final disposal ( Muisa et al ., 2011); aluminum sulfate is dependent on pH and acts in a restricted range, generally between 5.5 and 8, which generates chemical product expenditure and, therefore, an increase in the cost of the process (Silva et al ., 2020); Furthermore, there is a correlation between aluminum and Alzheimer's disease ( Krupińska , 2020).
In order to seek biodegradable alternatives, abundant in nature, with low environmental  Pezzarossi , 2004 ).It was classified by the French researcher Jean Baptiste Antoine Pierre de Monet de Lamarck (1744 -1829) and originates from India ( Pezzarossi , 2004).In Brazil, Moringa oleifera is also known as "moringa", "white lily " or "quina okra", and in other places in the world as "coxinha" or " horseradish " (Brilhante et al ., 2017).7

Moringa oleifera
According to Bezerra et al . (2004), Moringa oleifera is used in several fields: food (leaves, green fruits, flowers and roasted seeds); medicinal (all parts of the plant); condiment (mainly the roots), culinary and in the cosmetics industry (oil extracted from the seeds); melliferous (flowers); fuel; and water treatment.Ndabigengesere et al . (1995) found that Moringa oleifera seeds , shelled and shelled, can be used as a coagulant in water treatment.According to the authors, the coagulating action is due to the presence of cationic proteins that are soluble in water.
Ndabigengesere & Narasiah (1998) found that the volume of sludge generated by Moringa oleifera is 4 to 5 times smaller compared to the use of aluminum sulfate, as sulfate produces aluminum hydroxide as a precipitate.They add that Moringa oleifera sludge is organic and can be used as a fertilizer, as long as there are no heavy metals present in the water being treated.This fact can contribute to reducing costs with sludge treatment when opting for natural coagulant.According to the literature, the processing of seeds to extract their coagulating properties can be carried out in different ways, with no standardization.Some authors use a pestle to crush the seeds (Okuda et al ., 1999;Rocha et al ., 2020), others adopt the methodology of obtaining the powder using a domestic blender ( Ndabigengesere et al ., 1995) and even the preparation of the coagulant solution directly in the blender (Cardoso et al ., 2008).Arantes et al . (2012) evaluated and compared four equipment for seed processing: grinding machine, pestle, mixer and blender.They found that the most efficient methods for reducing turbidity were the grinding machine and the pestle.
Silva & Oliveira (2024) used natural coagulants based on Moringa oleifera seeds in their experimental work to clarify waters with an average turbidity of 50 uT .Two methodologies for processing the seeds were tested: using a pestle and using a blender.The best turbidity removal efficiencies were achieved when using the pestle as the processing method.
Furthermore, the authors produced the coagulants using shelled and shelled seeds, with the best results being obtained in shelled solutions.Using the shellless coagulant, the highest turbidity removal efficiency values were obtained and a lower concentration of coagulant was required.
Moringa oleifera seeds is promising for water treatment.However, there are still aspects that need to be investigated, especially in determining the ideal dosages for waters with high turbidity.This will contribute to advances in water treatment technology in a sustainable way.

HELICOIDAL TUBULAR FLOCCULATOR
The helical tubular flocculator (FTH) is a compact flocculation system that takes advantage of the kinetic energy of the hydraulic flow to promote the necessary agitation, mixing the coagulant in the liquid mass and, thus, flocs are formed ( Carissimi , 2003;Oliveira, 2008 ).It is composed of a rigid tube with a circular section, surrounded by a flexible hose, which can be wound helically horizontally or vertically (Oliveira, 2008, Sartori, 2015;Oliveira & Teixeira, 2017a, 2017b).Figure  In the study by Oliveira (2008), 24 FTH models were tested at two feed rates, with the aim of evaluating the influence of the FTH length on turbidity removal.For the construction of the FTH, the author varied the lengths and diameter of the hoses, while the winding tube was constant in all tests: 10 cm in diameter.The coagulant used in the tests was aluminum sulfate.
Among the results, it was verified that the turbidity removal efficiency increases until reaching a maximum value and then decreases with increasing reactor length.Therefore, an optimal length range was defined for turbidity removal efficiency under specific flow conditions.
Within the optimal length range for FTHs with 1/2 inch diameter hose, there are lengths of 11.84 m and 14.80 m.
In the work of Oliveira & Teixeira (2017b), the experimental results of turbidity removal efficiency with the processing time of a water clarification system were analyzed.The system consisted of an FTH coupled to a decanter.The results obtained showed that FTH is promising in the water clarification process and has a low flocculation time, less than 2 minutes.This represents around 10.0% of the time spent by traditional flocculators .
Armeloni et al .( 2020) studied the use of coagulant from Moringa oleifera seeds , together with FTH, as it is a low-cost and high-efficiency flocculator .The length of the FTH used was 10.53 m and volume of 7.5 x 10-4 m3.The authors obtained turbidity removal efficiency of 95.3% in a 30-minute decantation time.In the experiment, synthetic water was used with an initial turbidity of 148 uT , produced with bentonite.
In the literature, it was observed that FTHs are used in vertical and horizontal orientations.Table Table 1the guidelines for FTHs used in the work developed by some authors.
Although Armeloni et al . (2020) advanced FTH studies by using a natural coagulant from Moringa oleifera seeds , different lengths of FTHs nor variations in their orientation were tested .This lack of orientation variation is also shown in Table 1, in which the FTHs were tested in a single orientation.

Armeloni et al . (2020) Vertical
In the work of Silva & Oliveira (2024), 2 FTHs with different lengths were tested: 2.96 meters and 11.84 meters.Furthermore, both were tested in horizontal and vertical orientation, totaling 4 configurations tested.All configurations showed good turbidity removal results, with the best results being obtained with the horizontal orientation of the FTH.Furthermore, the shorter reactor presented the best process efficiencies, exceeding 90% turbidity removal when used with a natural coagulant based on Moringa oleifera seeds .
Moringa oleifera seeds in conjunction with FTH, encompassing tests for waters with diverse characteristics and treatment units with geometric characteristics.diverse, thus contributing to advances in the water clarification process in a sustainable and low-cost manner.

EXPERIMENTAL VALIDATION
Netra research laboratory , located at the Instituto Federal do Espírito Santo campus Cariacica, was tested ( Figure 3).Initially tap water was reserved in an elevated reservoir and, after opening a valve, the water was directed to a rotameter, where its flow rate was measured.After this step, high turbidity water was added to the main flow in order to obtain a fluid with a known turbidity value (in this work a turbidity of approximately 100 uT was tested ).The natural coagulant based on Moringa oleifera was added to this fluid and the fluid was then stirred with the help of FTH, placed horizontally.It is noteworthy that pressure gauges were inserted into the hydraulic system at the inlet and outlet of the reactor to determine the unit's pressure loss and, consequently, determine the average speed gradient.Finally, the fluid was taken to the decanter and, after the decantation stage, the final sample was removed to determine the final turbidity and, consequently, the turbidity removal efficiency.

Schematic representation of the hydraulic circuit
The natural coagulant was prepared from peeled Moringa oleifera seeds , at a concentration of 1g in 50mL of water.First, the seeds were peeled and weighed.They then macerated in a mortar and mixed with tap water on a magnetic stirrer for 10 minutes.
Finally, the mixture was filtered using filter paper.
The water used in all tests had an average turbidity of 100 uT , obtained by mixing tap water (reserved in the elevated reservoir) and water from the high turbidity reservoir (average value of 500 Ut), obtained through the addition of bentonite to water.The solution was prepared the day before the test and stored in bottles for later use in the experiments.To achieve turbidity of 500 uT , 2.49g of bentonite was added to every 2L of tap water.
To determine the ideal concentration of natural coagulant, 30 analyzes were carried out using a jar-test system , distributed in 3 different tests, each carried out in duplicate.
Concentrations varied from 2mL to 2mL, with a starting value of 2mL, as shown in Table 2.After testing in the jar-test , the concentration of 16mL was defined as the best to be used in the hydraulic circuit.The results are shown in After defining the best concentration of natural coagulant obtained through the jar-test (highlighted in Table 3), the value found was used in the hydraulic circuit described in  These results indicate that the technology used is highly efficient, as it was able to achieve a final turbidity below 5 uT without the need for a filtration step.This performance highlights the potential of the natural Moringa oleifera coagulant as a practical and efficient solution for water clarification, and can be a viable alternative to conventional treatment methods that often require additional filtration processes to achieve comparable levels of water quality.

CONCLUSIONS
This article performed a comprehensive review of the literature on the use of natural (a) perikinetic flocculation -resulting from Brownian movement and the action of gravity, in which destabilized colloidal particles collide and agglomerate, forming small flakes generally with dimensions smaller than 1μm; (b) orthokinetic flocculation -occurs from the addition of external energy (velocity gradient), which promotes the interaction of destabilized particles and small flakes formed by Brownian movement; (c) differential sedimentation -the flakes formed have different volumes and densities, therefore, they acquire different sedimentation speeds, which results in interactions and the formation of heavier flakes during the downward Water Treatment and Its Alternative Methodologies: Use of Natural Coagulants and Helically Coiled Tube Flocculators For Water Clarification ___________________________________________________________________________ Rev. Gest.Soc.Ambient.| Miami | v.18.n.8 | p.1-17 | e08522 | 2024.

Water
Treatment and Its Alternative Methodologies: Use of Natural Coagulants and Helically Coiled Tube Flocculators For Water Clarification ___________________________________________________________________________ Rev. Gest.Soc.Ambient.| Miami | v.18.n.8 | p.1-17 | e08522 | 2024.6 impact and that produce less sludge (Lima Júnior & Abreu, 2018), the use of natural coagulants as an alternative to chemical coagulants has been researched.It is clear that in the literature there are a variety of natural coagulants derived from plants.Among these coagulants, Moringa oleifera stands out.This highlight was also verified in the work of Armeloni et al .(2020), in which around 42.0% of the articles found used Moringa oleifera seeds as a natural coagulant, while the other 58.0%represented other natural coagulants.2.3 USE OF MORINGA OLEIFERA IN WATER TREATMENT Moringa oleifera Lamarck is the most widespread species in the Moringaceae family ( Figure 1the pods and seeds of Moringa oleifera .

Okuda
et al .(1999)  compared the use of sodium chloride saline solution and distilled water in the extraction of active components from Moringa oleifera seeds, in the removal of turbidity from 50 uT synthetic water .The best results in turbidity removal efficiency were using sodium chloride saline solution.Muniz et al . (2015) carried out a study to compare the effects of using coagulant solutions prepared from shelled and shelled Moringa oleifera seeds in reducing the turbidity of waters with different turbidity levels.Samples for turbidity analysis were collected after filtering the decanted water, filtration was carried out with the aid of a vacuum pump.The highest turbidity removal efficiency found by the authors was 98.73% using the shelled seed solution, with 120 minutes of sedimentation.Rocha et al . (2020) evaluated the turbidity removal efficiency of Moringa oleifera coagulants extracted by aqueous and saline solutions and found that the efficiency found for both solutions was very close, for the aqueous solution it was 92.0% to 95.0% and for saline solution from 90.0% to 94.0%.The authors also found that the use of aluminum sulfate reduces the pH of the solution, which makes correction necessary.However, when using Moringa oleifera , there is no need for correction as the pH remains in the same range, resulting in a decrease in reagent costs.Michelan et al . (2021) carried out a study in which they tested the coagulant from Moringa oleifera seeds , both shelled and shelled, in water treatment, simulated in the jar-test , from coagulation to filtration.The raw water used in the study was natural water of low turbidity, with values between 17 and 27 uT .The study found that Moringa oleifera has Water Treatment and Its Alternative Methodologies: Use of Natural Coagulants and Helically Coiled Tube Flocculators For Water Clarification ___________________________________________________________________________ Rev. Gest.Soc.Ambient.| Miami | v.18.n.8 | p.1-17 | e08522 | 2024.8 potential as a coagulant for water treatment, with satisfactory removal of color and turbidity, depending on the concentration used.

Figure 2shows
Figure 2shows the representative scheme of the FTH, with the diameter of the hose and D being the diameter of the rigid tube.

Figure 2
Figure 2Representative scheme of FTH

Figure 4 Final
Figure 4Final turbidity values and turbidity removal efficiency obtained with the use of the alternative clarification system in conjunction with the natural coagulant based on Moringa oleifera .
coagulants and Helical Tubular Flocculators ( FTHs ) in alternative water clarification processes, providing a detailed overview of their advantages over traditional methods.The theoretical analysis was accompanied by a laboratory-scale experiment, which highlighted the practical potential of the natural coagulant based on Moringa oleifera in conjunction with FTHs for the efficient removal of turbidity.The experimental results demonstrated a remarkable efficiency in turbidity removal, reaching values greater than 95% of turbidity removal in 60 minutes of decantation, with a final turbidity of 4.88 uT .This value is below the limit of 5 uT established by Ordinance of the Ministry of Health GM/MS No. 888, of May 4, 2021, for points in the distribution network, and was obtained without the need for additional filtration steps.These findings indicate that the combination of natural coagulants and FTHs offers an effective and sustainable solution for water treatment, standing out as a viable alternative to conventional methods that require greater investments in infrastructure and greater operational complexity.The use of natural coagulants, combined with the simplicity and efficiency of FTHs , can represent a significant advance in addressing global water treatment challenges, promoting environmental and operational benefits.Future research could explore optimizing these technologies for different water conditions and application scales, solidifying their role as an essential tool in environmental engineering.

Table 2
Concentrations tested in jar-test

Table 3
Final turbidity results in jar-test