Aloe Vera in Water Treatment: Toward a Greener Future for Environmental Engineering

Abstract

The use of natural solutions has gained increasing attention as a sustainable alternative for water treatment. In this study, an Aloe vera-based coagulant was evaluated through jar test experiments and a laboratory-scale hydraulic system consisting of an alternative flocculator (such as a helically coiled tube) followed by sedimentation and filtration processes. The jar test experiments demonstrated high turbidity removal efficiency, achieving final turbidity values of 5 NTU or lower under all the tested conditions, in accordance with international environmental regulations and standards. Moreover, in some conditions, turbidity was completely eliminated, highlighting the remarkable coagulation performance of Aloe vera. In the hydraulic system, the results indicated a significant turbidity reduction, with turbidity removal efficiencies of up to 97%, coagulation/flocculation times under 2 min, and sedimentation times of 60 min. However, the combined coagulation, flocculation, and sedimentation processes were not sufficient to reduce the final turbidity to below 5 NTU, demonstrating the need for an additional rapid filtration step. The inclusion of this process further enhanced the particle removal, resulting in final turbidity values below 1 NTU, well within the regulatory limits. These results highlight the potential of the tested natural coagulant for application in water treatment systems, establishing it as a sustainable and cost-effective solution for water clarification, with promising prospects for large-scale implementation.

1. Introduction

The access to potable water remains one of the most pressing challenges of the 21st century, particularly in regions with limited infrastructure for water treatment and distribution [1,2,3]. The lack of an adequate water supply exposes millions of people to untreated water consumption, increasing the risk of waterborne diseases and compromising the quality of life in the affected communities [4,5,6]. In this context, ensuring universal access to safe drinking water is not only a public health priority but also a fundamental pillar of social equity and sustainable development [7].

To address these challenges, the United Nations (UN) established the 2030 Agenda for Sustainable Development, which comprises 17 Sustainable Development Goals (SDGs) [8,9]. Among these, SDG 6: Clean Water and Sanitation aims to ensure equitable and universal access to safe drinking water and adequate sanitation by 2030 [10,11,12]. In Brazil, the data from the National Sanitation Information System (SNIS) indicate that approximately 15.9% of the population still lack access to a public water supply network, underscoring the need for innovative and sustainable water treatment solutions [13]. On a global scale, the situation is even more alarming: a 2024 study published in Science revealed that more than 4 billion people—over half of the world’s population—lack access to safe drinking water in their homes [14]. Given this scenario, the development of accessible and sustainable technologies is imperative to uphold the human right to potable water, promoting health, dignity, and improved living conditions for vulnerable populations worldwide.

The quality of drinking water is regulated in Brazil by the Ministry of Health, which establishes potability criteria to ensure public health protection. Ordinance GM/MS No. 888, issued on 4 May 2021, defines the procedures for monitoring and controlling the water quality, including the maximum allowable limits for various physical, chemical, and microbiological parameters. Among these, the turbidity levels in drinking water must not exceed 5 nephelometric turbidity units (NTU), as higher values can compromise the disinfection efficiency and indicate the presence of particulate matter that may harbor pathogenic microorganisms [15].

Therefore, the development and evaluation of water clarification systems are crucial for ensuring compliance with the potability standards established by national regulations. These systems play a fundamental role in water and wastewater treatment, removing impurities, sediments, and suspended particles to produce cleaner, clearer, and safer drinking water.

Currently, most water treatment plants employ conventional treatment methods, which typically consist of coagulation, flocculation, sedimentation, filtration, and disinfection [16,17]. While these processes are effective, the use of chemical coagulants, such as aluminum sulfate and ferric chloride, poses significant environmental and economic challenges, in addition to potential health risks. These include the generation of non-biodegradable sludge and the presence of residual chemicals that have been associated with neurological disorders [18]. Consequently, the search for natural coagulants has intensified as a sustainable, accessible, and environmentally friendly alternative for water treatment [19].

Among the natural coagulants studied, Aloe vera has garnered attention due to its bioflocculant properties, attributed to polysaccharides and bioactive compounds that enhance particle aggregation in suspensions [20]. The recent studies indicate that Aloe vera extracts can achieve high turbidity removal efficiencies, reducing the need for chemical coagulants and offering an economically viable alternative for simplified water treatment systems [21,22,23]. Moreover, the utilization of natural materials as coagulants supports the development of decentralized and sustainable technologies, fostering solutions adaptable to diverse socio-economic contexts [24].

Beyond the selection of a coagulant, the design of the flocculation unit plays a critical role in the clarification efficiency. In this regard, helically coiled tube flocculators (HCTFs) have emerged as an innovative alternative, providing hydrodynamic conditions conducive to floc formation and growth, while significantly reducing the flocculation time [25,26]. These systems are compact, cost-effective, and energy-efficient, eliminating the need for mechanical mixing, making them a promising solution for communities lacking the conventional treatment infrastructure [27]. However, despite these advantages, the application of HCTFs in combination with natural coagulants remains largely unexplored. The majority of previous studies on HCTFs have focused on conventional coagulants, leaving a significant gap in understanding how natural alternatives, such as Aloe vera, interact with the hydrodynamics of these systems. Moreover, although Aloe vera has been investigated for its coagulation properties, there is limited research on its efficiency in continuous-flow systems or its performance when integrated with innovative flocculation units.

Thus, this study aimed to fill this research gap by evaluating the performance of an Aloe vera-based natural coagulant for turbidity removal in water treatment, utilizing both jar test experiments and a laboratory-scale hydraulic system incorporating HCTFs for coagulation and flocculation. By analyzing the process efficiency in terms of the coagulation, flocculation, and sedimentation times, this research contributes to advancing sustainable and accessible technologies, particularly for water treatment in communities with limited infrastructure.

2. Methodology

This section describes the procedures adopted to evaluate the efficiency of the Aloe vera-based natural coagulant in turbidity removal through jar test experiments and an alternative water treatment system. Initially, the coagulant was prepared to ensure the standardization of the solution used in the experiments. Subsequently, synthetic water was formulated to simulate turbid water conditions, maintaining a consistent initial turbidity across the samples. The experiments were conducted in two stages: (i) jar test assays to assess the coagulation/flocculation under controlled conditions and (ii) a laboratory-scale hydraulic system to analyze the coagulant’s performance in an alternative flocculation system.

2.1. Preparation of the Aloe Vera-Based Natural Coagulant

The natural coagulant was prepared immediately before each experiment to preserve its bioactive properties. Fresh Aloe vera leaves were manually selected and subjected to gel extraction (Figure 1a), which constitutes the active component of the natural coagulant.

The preparation process followed a standardized protocol, in which 2 g of Aloe vera gel (Figure 1b) was added to 50 mL of tap water, resulting in a 40 mg/mL solution. The mixture was homogenized in a blender for 1 min to promote gel emulsification (Figure 1c). Subsequently, the solution was filtered using filter paper placed over a beaker (Figure 1d) to remove solid residues, ensuring a homogeneous solution for the experimental tests (Figure 1e).

2.2. Preparation of Synthetic Water

To ensure standardized analyses and simulate the representative conditions of turbid waters, synthetic water was used in the experiments. Synthetic water is a laboratory-prepared solution designed to replicate the physicochemical characteristics of natural water, allowing controlled experiments in water treatment and quality research. Its composition may include various substances, such as clays, organic matter, and dissolved salts, depending on the study’s objective.

In this study, the formulation of synthetic water followed the established protocols from the literature [28], utilizing bentonite as a turbidity-inducing agent due to its stability and ability to provide controlled turbidity levels. Bentonite, a clay primarily composed of montmorillonite, is widely used in water treatment studies as it forms stable colloidal suspensions, ensuring the reproducibility of the experimental conditions. Since the primary objective of this study was to evaluate the turbidity removal, turbidity was the main control parameter. Thus, the initial turbidity of the synthetic water was the only variable adjusted during the sample preparation, ensuring an appropriate experimental environment for assessing the performance of the tested clarification system.

The preparation process involved adding 0.246 g of bentonite to each 2 L jar containing tap water, resulting in an average turbidity of 50 NTU. To achieve higher turbidity levels, the bentonite concentration was adjusted proportionally by increasing the amount of material needed. After the bentonite was added, the solution underwent intense stirring for 30 min to ensure the homogeneous dispersion of the suspended particles.

Each 2 L sample of synthetic water was stored in a sealed bottle for at least 24 h before the experiment to allow particle stabilization, ensuring uniform conditions for testing. Before each trial, the solution was re-homogenized to guarantee the adequate distribution of suspended solids.

The initial turbidity was measured using a calibrated turbidimeter, which served as the reference value for assessing the coagulant’s effectiveness in turbidity removal at the end of the tests.

2.3. Jar Test Experiments

Experiments performed with the jar test apparatus were conducted to evaluate the efficiency of the coagulant in regard to turbidity removal under controlled laboratory conditions. The tests were performed using jar test apparatus equipped with six 2 L beakers (Figure 2), which were filled with the synthetic water prepared as described in Section 2.2.

The jar test experiments were conducted following the experimental protocol outlined below:

• Coagulation/flocculation—Stirring at 150 rpm for 1 min and 11 s to promote the formation and growth of flocs. The flocculation time selected was based on [26]. It is important to highlight that the reduced value is related to the alternative flocculation technology employed in this work.
• Sedimentation—A 60 min settling period, with sample collection at 10 min intervals for turbidity analysis.

Tests were performed with initial turbidity levels of 50, 100, 200, and 300 NTU to evaluate the efficiency of the Aloe vera-based coagulant under different turbidity conditions. To ensure the data reproducibility and reliability, all the turbidity measurements were conducted in triplicate, allowing for a robust assessment of the coagulant’s performance across the tested turbidity ranges.

During the jar test assays, 60 to 120 mL of the coagulant solution was added to the jars, in 5 mL increments. Considering the prepared coagulant concentration (40 mg/mL), the applied coagulant masses ranged from 2.4 g to 4.8 g. The volumes of coagulant solution and their corresponding masses for each turbidity level are presented in

Table 1. Coagulant solution volume and corresponding mass for an initial turbidity of 50 NTU.

Container	Jar 1	Jar 2	Jar 3	Jar 4	Jar 5	Jar 6
Coagulant volume (mL)	60	65	70	75	80	85
Coagulant mass (g)	2.4	2.6	2.8	3.0	3.2	3.4

,

Table 2. Coagulant solution volume and corresponding mass for an initial turbidity of 100 NTU.

Container	Jar 1	Jar 2	Jar 3	Jar 4	Jar 5	Jar 6
Coagulant volume (mL)	50	55	60	65	70	75
Coagulant mass (g)	2.0	2.2	2.4	2.6	2.8	3.0

,

Table 3. Coagulant solution volume and corresponding mass for an initial turbidity of 200 NTU.

Container	Jar 1	Jar 2	Jar 3	Jar 4	Jar 5	Jar 6
Coagulant volume (mL)	80	85	90	95	100	105
Coagulant mass (g)	3.2	3.4	3.6	3.8	4.0	4.2

and

Table 4. Coagulant solution volume and corresponding mass for an initial turbidity of 300 NTU.

Container	Jar 1	Jar 2	Jar 3	Jar 4	Jar 5	Jar 6
Coagulant volume (mL)	95	100	105	110	115	120
Coagulant mass (g)	3.8	4.0	4.2	4.4	4.6	4.8

.

The coagulation/flocculation time and mixing conditions were defined based on the operational characteristics of the coagulation/flocculation unit used in the hydraulic system.

The remaining turbidity was measured using a calibrated turbidimeter. The turbidity removal efficiency was calculated based on the initial and final turbidity values, allowing for a comparative analysis across different experimental conditions.

2.4. Laboratory-Scale Hydraulic System Experiments

Following the jar test assays, the efficiency of the natural coagulant was evaluated in a laboratory-scale hydraulic system, which consisted of a helically coiled tube flocculator (HCTF), a conventional sedimentation system, and a rapid filter (Figure 3). This system was designed to simulate the conditions more representative of continuous water treatment systems, enabling the assessment of the coagulant’s feasibility in an alternative clarification setup. In Figure 3, the sampling points are indicated as follows: (1) raw water inlet—represents the initial turbidity of the water before treatment; (2) after sedimentation—measures the turbidity following the coagulation, flocculation, and sedimentation processes; (3) after filtration—the final turbidity measurement following the filtration step.

The experimental system consisted of a clean water reservoir (turbidity = 0 NTU), a concentrated synthetic water reservoir, an HCTF, a conventional sedimentation unit, and a rapid filter. Initially, zero-turbidity water was mixed with the concentrated synthetic water solution until the desired initial turbidity was achieved: 100 NTU in Test 1 and 200 NTU in Test 2. These values were selected as they represent the intermediate conditions within the turbidity range assessed in the jar test experiments, optimizing the trials without compromising the representativeness of the analysis.

Once the turbidity was stabilized, the Aloe vera-based natural coagulant was introduced into the mixture via a dosing pump (OFA brand), ensuring precise and homogeneous dosing. The system operated at a constant flow rate of 1 L/min, maintaining controlled and reproducible conditions throughout all the tests.

The treated solution was then directed into the HCTF, where the turbulent flow induced by the equipment’s geometry promoted intense mixing between the coagulant and suspended particles, facilitating floc formation and growth. The geometric characteristics of the HCTF are presented in Figure 4.

Next, the mixture was conveyed to the sedimentation unit, where flocculated particles were removed via gravitational settling. During this process, samples were collected every 10 min to determine the residual turbidity, allowing an efficiency analysis of the coagulant over time.

Finally, the clarified water was passed through the filtration unit (Figure 5), following the methodology proposed in [29].

2.5. Analysis of the Turbidity Removal Efficiency

The assessment of the clarification system’s performance was directly linked to its ability to remove turbidity. Throughout the experimental trials, the effectiveness of turbidity removal was evaluated in both the jar test apparatus and the alternative water clarification system. This analysis sought to establish a relationship between the fraction of flocculated and settled particles and the total initial solid content at the start of the process. The efficiency of turbidity removal was determined using Equation (1):

$$\mathrm{Efficiency}\left(\mathrm{\%}\right)=\left(1-{\displaystyle \frac{\mathrm{Finally} \mathrm{turbidity}}{\mathrm{Initial} \mathrm{turbidity}}}\right)\times 100$$

(1)

Turbidity measurements were conducted using a nephelometric turbidimeter, a technique that relies on the scattering of a light beam by the particles in the analyzed sample. The instrument determines the turbidity by comparing the intensity of scattered light against a calibration standard, where greater scattering corresponds to higher turbidity levels [30]. In this study, all the turbidity measurements were performed using an Akso TU 430 turbidimeter (Akso, located in Rio Grande do Sul, Brazil). For the turbidity measurement, 10 mL samples were collected. The turbidity analysis was performed immediately after the sample collection to ensure accurate and reliable results.

3. Results and Discussion

This section presents the results obtained from the jar test experiments (Section 3.1) and evaluates the performance of the alternative water clarification system (Section 3.2), along with their respective analyses and interpretations.

3.1. Jar Test Results

This section presents the results of the jar test experiments conducted with the natural coagulant, aiming to assess its efficacy in turbidity removal and determine the optimal coagulant concentration. Figure 6, Figure 7, Figure 8 and Figure 9 illustrate the final turbidity values obtained for the different concentrations of the Aloe vera-based natural coagulant tested. Throughout all the experiments, the pH remained stable between 6.9 and 7.2, reflecting a typical characteristic of natural coagulants, which generally do not cause significant changes in pH values, unlike chemical coagulants that often require pH adjustment during water treatment processes. For performance evaluation, the jars that exhibited the lowest final turbidity after the total sedimentation time were considered the most effective.

The jar test experiments demonstrated that, within a maximum sedimentation time of 60 min, the turbidity levels achieved complied with the potability limit established by Brazilian regulation GM/MS No. 888/2021, which defines the national drinking water standards. According to this regulation, potable water turbidity must not exceed 5 NTU, regardless of the initial turbidity level (50, 100, 200, or 300 NTU).

This finding is significant, as high turbidity levels can compromise the disinfection efficiency by shielding pathogenic microorganisms, making them more difficult to inactivate. Additionally, excessive turbidity can cause undesirable water characteristics, such as discoloration and the presence of suspended solids. Thus, meeting the potability standards is a critical factor in determining the feasibility of any water treatment system.

Beyond confirming the natural coagulant’s efficiency in turbidity control, the jar test results provide valuable information for the application of an alternative clarification system, enabling the optimization of its operating conditions. Identifying the optimal coagulant concentrations for different initial turbidity levels was essential for establishing the efficiency parameters and assessing the feasibility of large-scale implementation.

For samples with an initial turbidity of 50 NTU, the most effective dosage was 60 mL of coagulant solution, corresponding to 2.4 g of natural coagulant. For the 100 NTU samples, the optimal concentration was 75 mL (3.0 g of coagulant), ensuring effective turbidity removal over time. For samples with 200 NTU, the ideal dosage was 100 mL (4.0 g of coagulant), with the turbidity reaching zero NTU within 40 min, demonstrating the rapid action of the coagulant. Similarly, for the 300 NTU samples, the best concentration was 115 mL (4.6 g of coagulant), which resulted in a turbidity below 5 NTU within 20 min and zero NTU in 30 min.

The efficient turbidity reduction, even in highly turbid water, highlights the potential of the natural coagulant for various applications, including scenarios where the infrastructure for conventional water treatment is limited. Additionally, the relatively short time required to meet the regulatory limits reinforces its feasibility, suggesting that it may serve as a promising alternative for simplified clarification systems.

These results are particularly relevant for communities facing challenges in accessing potable water, as they emphasize the need for effective, accessible, and environmentally sustainable water treatment solutions.

The analysis of the optimal coagulant dosages for each initial turbidity level reveals an interesting relationship between the amount of coagulant applied and the raw water turbidity. As shown in Figure 10, an increase in initial turbidity corresponds to a higher coagulant mass requirement to achieve the optimal efficiency.

The relationship presented in Figure 10 indicates that the coagulant demand does not increase linearly with a rising initial water turbidity. A logarithmic-based model was successfully obtained, demonstrating a strong fit to the experimental data. The p-values obtained for the coefficients of the logarithmic model shown in Figure 10 were 0.0054 for the coefficient of the natural logarithm term and 0.0369 for the constant term. Statistically, both p-values are below the commonly accepted significance level of 0.05, indicating that the coefficients are significantly different from zero. This suggests that both the logarithmic relationship and the constant term meaningfully contribute to explaining the variability in the response variable within the model. The coefficient of determination ($R^2$) and the adjusted $R^2$ ($R_{adj}^2$) values were both above 0.98, indicating a high-quality fit. The use of the $R_{adj}^2$ is particularly recommended when the dataset size is limited, as this metric accounts for the influence of the sample size on the determination coefficient. By incorporating this adjustment, the metric provides a more reliable evaluation of the model’s explanatory power. A high $R_{adj}^2$ value further reinforces the robustness of the proposed model, confirming its suitability for describing the observed phenomena [31].

At higher turbidity levels, a stabilization trend is observed in the required coagulant dosage, as shown in Figure 10. This behavior suggests the presence of a threshold beyond which further increases in the initial turbidity result in only marginal dosage adjustments while still maintaining efficient turbidity removal. This behavior may be attributed to the following: (a) the saturation of the active sites in the coagulant, which limits its ability to induce additional particle aggregation, and (b) the formation of denser and more cohesive flocs at higher turbidity levels, which enhances the removal of suspended particles with minimal variations in the coagulant dosage.

Understanding this relationship is essential for process optimization, as it enables precise coagulant dosage adjustments, ensuring operational efficiency while minimizing the waste in water treatment. These findings suggest that the relationship between the initial turbidity and required coagulant mass follows a nonlinear trend, approaching a logarithmic behavior, where the coagulant dosage increases are not directly proportional to the initial turbidity increments.

This phenomenon may indicate a limit in the coagulant’s ability to enhance the turbidity removal beyond a certain concentration, reinforcing the need for process optimization to avoid excessive dosages that do not yield significant improvements in water clarification.

3.2. Hydraulic System Results

The hydraulic system evaluation was conducted using the optimal coagulant dosages determined from the jar test experiments for the initial turbidity levels of 100 NTU (Test 1) and 200 NTU (Test 2). The coagulant’s efficiency was analyzed over time, under a constant flow rate of 1 L/min, allowing an assessment of turbidity removal behavior in a continuous system (Figure 11). During this testing phase, the coagulation, flocculation, and sedimentation stages were analyzed using Aloe vera-based natural coagulants, verifying the effectiveness of these stages in the water treatment process. The final turbidity values were obtained for the different concentrations of the Aloe vera-based natural coagulant tested. The pH remained consistently stable between 6.9 and 7.2 across all the experiments, a behavior characteristic of natural coagulants, which typically do not significantly alter the pH levels.

The turbidity variation over time for both tests showed a significant reduction within the first 10 min, followed by a more gradual decline throughout the experiment. In Test 1 (100 NTU), the initial average turbidity was 99.27 NTU, decreasing to 63.30 NTU at 10 min and reaching 25.80 NTU by the end of 60 min. In Test 2 (200 NTU), the initial average turbidity of 199.83 NTU rapidly dropped to 29.63 NTU at 10 min, further decreasing to 15.33 NTU at the end of the experiment.

The turbidity removal efficiency values demonstrated the promising performance of the natural coagulant in the hydraulic system (Figure 12). In Test 1 (100 NTU), the turbidity removal efficiency was 36.2% at 10 min, increasing to 59.9% at 20 min, and stabilizing at 74.0% by 60 min. In Test 2 (200 NTU), the turbidity removal efficiency was even higher, reaching 85.2% at 10 min, 88.6% at 20 min, and 92.3% by the end of the experiment. These results indicate that the alternative clarification system has great potential for application in simplified water treatment contexts, exhibiting a high capacity for removing suspended particles.

However, despite the promising results, the final turbidity values remained above the regulatory limit, indicating that the alternative system still requires adjustments to achieve clarification efficiency in compliance with the potability standards. According to the Brazilian Ministry of Health regulation GM/MS No. 888/2021, the turbidity of drinking water must not exceed 5 NTU, a threshold that was not reached in the tested hydraulic system when only coagulation, flocculation, and sedimentation were applied. This finding suggests that filtration is necessary to further reduce the turbidity levels to meet the potability standards, ensuring that the treated water is suitable for human consumption as required by the current legislation. The results of the filtration stage for both tests conducted in the hydraulic system are presented in

Table 5. Final turbidity and turbidity removal efficiency after the filtration stage.

Test	Initial Water Turbidity (NTU)	Final Turbidity After Sedimentation (NTU)	Final Turbidity After Filtration (NTU)	Turbidity Removal Efficiency After Sedimentation (%)	Turbidity Removal Efficiency After Filtration (%)
Test 1 (100 NTU)	99.27	25.88	0.62	74.0%	99.4%
Test 2 (200 NTU)	199.83	15.33	0.96	92.3%	99.5%

.

The results obtained demonstrate the effectiveness of the tested system in turbidity removal, particularly after the filtration stage. As shown in Table 5, the turbidity removal efficiency after sedimentation ranged between 74.2% and 92.3%, indicating that while sedimentation significantly reduced the initial turbidity, the final values still exceeded the recommended threshold for drinking water. Nevertheless, sedimentation plays a fundamental role in water treatment, as it allows for the preliminary removal of suspended solids, thereby reducing the particle load entering the filtration stage. This process enhances the filtration efficiency and longevity, decreases the backwashing frequency, and contributes to the system’s operational stability.

The promising performance of the Aloe vera-based coagulant observed in this study can be attributed to its biochemical composition, especially its high polysaccharide content, which plays a fundamental role in the particle aggregation during the coagulation and flocculation processes. According to [23], the presence of polysaccharides favors the bridging mechanisms between suspended particles, promoting the formation of larger and more stable flocs. Furthermore, the molecular weight of these biopolymers contributes to the efficiency of the flocculation process, as higher molecular weights tend to improve the particle capture and sedimentation. These biochemical properties help explain the high turbidity removal rates observed and reinforce the potential of Aloe vera as a sustainable and efficient natural coagulant for water treatment applications.

It is important to note that an excess of coagulant can even worsen the turbidity removal effect, so the dose must be optimal, preferably determined experimentally. Additionally, the conditions in the jar test and hydraulic system are different, which leads to varying efficiencies between the two systems.

With the addition of filtration, a significant increase in the turbidity removal was observed, achieving efficiencies above 99%, regardless of the initial water turbidity. These results highlight the importance of filtration as a complementary stage to ensure the treated water quality, making it compliant with the potability standards.

Although the results demonstrate the effectiveness of the proposed system in turbidity removal, it is important to acknowledge the potential risks and limitations. The use of natural coagulants may pose risks related to microbial contamination and increased organic loading if not properly managed. Additionally, the transition from laboratory-scale experiments to large-scale applications presents challenges, including maintaining the process stability over extended periods and adapting the operational parameters to the real-world variations in the water quality. The long-term performance and storage stability of the natural coagulant must also be carefully evaluated to ensure a consistent treatment efficiency. Future studies should address these aspects through detailed monitoring and pilot-scale testing to support the safe and sustainable implementation of the proposed technology.

4. Conclusions

This study evaluated the efficiency of an Aloe vera-based natural coagulant for turbidity removal, employing two distinct methods: jar test experiments and a continuous-flow hydraulic system consisting of an HCTF, a conventional sedimentation system, and a rapid filtration unit.

In the jar test experiments, the results demonstrated effective turbidity removal, achieving the 5 NTU threshold established by the Brazilian environmental regulations for the drinking water quality (GM/MS No. 888/2021). Determining the optimal coagulant concentrations was essential for assessing its clarification capacity, showing that for the initial turbidity levels of 50, 100, 200, and 300 NTU, the most efficient dosages were 60 mL (2.4 g), 75 mL (3.0 g), 100 mL (4.0 g), and 115 mL (4.6 g), respectively. The relatively short times required to reduce the turbidity to below 5 NTU further reinforce the potential of this coagulant as a sustainable alternative for water treatment.

However, when applying the optimal jar test dosages to the hydraulic system, it was observed that sedimentation alone, despite promoting a significant turbidity reduction, was insufficient to reach the regulatory limit of 5 NTU. In Test 1 (100 NTU), the final turbidity was 25.80 NTU after sedimentation, while in Test 2 (200 NTU), it reached 15.33 NTU. Nevertheless, with the addition of filtration, the final turbidity values were reduced to 0.62 NTU and 0.96 NTU, respectively, achieving turbidity removal efficiencies exceeding 99%. These findings highlight the crucial role of filtration in ensuring that treated water meets the established environmental standards for potable water.

The differences observed between the jar test and hydraulic system results suggest that the hydrodynamic behavior in the continuous-flow system directly impacts the process efficiency, emphasizing the need for the further refinement of the operational conditions and hydraulic, geometric, and hydrodynamic parameters of the treatment units.

In addition to its efficiency, the Aloe vera-based natural coagulants present a cost-effective and environmentally friendly alternative to conventional chemical coagulants. Its application in decentralized and low-cost water treatment systems could significantly benefit communities lacking the access to conventional infrastructure. The absence of toxic residues and the biodegradable nature of Aloe vera also contribute to the reduced environmental impact compared to aluminum- or iron-based coagulants. Furthermore, the simplicity of the preparation process facilitates its implementation in resource-limited settings, reinforcing its viability for large-scale applications.

Future studies should focus on optimizing the key operational parameters, such as sedimentation time and flocculation dynamics, to enhance the treatment efficiency. Additionally, the integration of alternative filtration materials and hybrid treatment strategies could further improve the water quality. Investigating the long-term stability of the coagulant, its storage conditions, and its performance under different water quality conditions will also be essential for its practical implementation. Moreover, pilot-scale studies in real-world scenarios will be crucial to validate the laboratory findings and facilitate technology transfer to communities in need.

In addition to these aspects, future research should also include a comprehensive evaluation of the sustainability metrics, economic feasibility, and life cycle assessment (LCA) of the proposed treatment method. Analyzing the environmental impacts, resource consumption, and cost-effectiveness compared to the conventional technologies will be essential to assess their long-term viability and scalability. Such studies will provide a broader understanding of the advantages and limitations of using natural coagulants in sustainable water treatment systems, contributing to the development of more eco-efficient and economically viable solutions.

Overall, the results are promising, indicating that the tested natural coagulant could be a viable alternative for simplified water treatment systems, particularly in regions with limited infrastructure. The integration of filtration into the system proved to be an effective solution for achieving the quality standards required for human consumption. By addressing the aspects, future research can further consolidate Aloe vera-based coagulants as a sustainable and scalable solution for water treatment.