Utilization of aloe vera as a biocoagulant for turbidity, total dissolved solid (TDS), and iron (Fe) removal in well water

Well water contains several contaminant loads that need to be removed before use, such as turbidity, TDS, and Fe metal. One method of well water treatment is coagulation. Aloe vera has the potential to be an appropriate coagulant because it contains polygalacturonic acid, carboxyl groups (-COOH), and amide groups (-NH) that can help increase coagulation efficiency. The purpose of this study was to analyse the removal efficiency of turbidity, Fe metal and TDS using Aloe vera extract with HCl and H2O solutions. The coagulant doses used were 0.5 ml, 1.0 ml and 1.5 ml, fast stirring 120 rpm for 1 minute while slow stirring was carried out at 30 rpm for 10, 20 and 30 minutes. In the extraction of Aloe vera with HCl solution, the optimal dose and slow stirring time were obtained as 0.5 ml and 10 minutes for turbidity, 0.5 ml and 20 minutes for TDS and 1 ml and 10 minutes for Fe metal with efficiencies of about 96.99%, 8.05% and 70.85%, respectively. In H2O solution, the optimal dosage and slow stirring time were 0.5 ml and 10 min for turbidity and TDS with efficiencies of 91.76% and 3.09%, respectively. For Fe metal, the optimal dose and time were 1.5 mL and 20 minutes with removal efficiency of 6.39%.


Introduction
Wells are one of the commonly used methods for people to obtain clean water.In accordance with the Regional Regulation of Balikpapan City No. 3 Year 2008 which regulates the Regional Water Company (PDAM) of Balikpapan City, PDAM targets to serve 80% of the population, but by 2022 it will only reach 65.53%.Meanwhile, 20.26% of the population uses borehole wells/pumps [1].Nevertheless, well water has a number of problems, including turbidity, TDS levels, and high iron metal content.Special technology is needed to remove TDS, turbidity, and iron metal content contained in well water.
Coagulation is applied to remove suspended colloidal particles and reduce the level of turbidity in water.In the coagulation process, coagulants are added to enhance the clumping process.The coagulant used is a compound with a positive ion charge (H + ), to balance the negative ion charge (OH -) in the treated water or waste [2].Natural ingredients as coagulants provide the advantage of being biodegradable, safe for health, and an economically affordable alternative [2,3].One of the natural ingredients that can be utilised as a coagulant is Aloe vera.
Aloe vera has mucilage which contains complex carbohydrates and sugars that play a role in binding solid particles in water [4].Aloe vera also contains polygalacturonic acid and Zn which act as coagulant substances [5].Carboxyl groups (-COOH) and amide groups (-NH) in Aloe vera have a role in adsorption of suspended solids and form molecular bonds with coagulants, so as to increase efficiency in the coagulation process [6].Efficiency in the use of Aloe vera can also be improved by the extraction

Tools and materials preparation
The tools needed in this study are: 500 ml beaker glass, jar test tool, turbidimeter, pestle and mortar, volume pipette, EC meter, vacuum pump, suction rubber and oven.Meanwhile, the materials needed are: well water samples, Aloe vera, distilled water, 1 M and 0.05 M HCl solution, 1 M NaOH solution, and 2.5 μm filter paper (HAWACH BIO-42-110).

Research Variables
The independent variables in this study can be seen in Table 1 below.

Determination of optimum pH
Determination of optimum pH was carried out before performing the main research which intended to determine the optimal pH conditions for the coagulant.Well water has a pH range between 5.7 -7.5 which does not support the effectiveness of the coagulation-flocculation process.pH determination was carried out by adding 1 M NaOH and 1 M HCl to obtain pH 5, 6, 7, and 8 in well water.Then followed by the addition of Aloe vera coagulant as much as 1.5 mL into a 500 mL beaker containing well water.Afterwards, the coagulation and flocculation process was carried out with a fast stirring speed of 120 rpm for 1 minute and a slow stirring speed of 30 rpm for 30 minutes.The optimum pH was determined based on the highest decrease in turbidity after settling for 30 minutes.

Preparation of coagulant from aloe vera
Aloe vera is processed by rinsing with water and drying with an oven at 60℃ for 24 hours.After that, the dried Aloe vera was then mashed and sieved using a porous sieve with a size of 0.35 mm.A total of 25 g of Aloe vera powder was added to 1000 mL of distilled water with a mixture of 0.05 M HCl as much as 4.15 mL for extraction with HCl solution.While for extraction using H2O solution, 25 g of Aloe vera powder was added to 1000 mL of distilled water.Furthermore, the two solutions were each stirred with a magnetic stirrer at 700 rpm for 20 minutes.This aims to extract active coagulant material from Aloe vera.Then precipitation was carried out for 30 minutes, then filtered using filter paper with a porosity of 2.5 μm with the help of a vacuum pump, and the filtrate was used as a liquid coagulant material.
2.5.Coagulation process using jar test instrument 500 ml of sample water was measured using a glass beaker.Aloe vera extraction solution with a predetermined dose (0.5 ml, 1.0 ml, and 1.5 ml) was mixed into the water sample.Furthermore, the sample was then stirred using a jar test instrument with a batch system at a stirring speed of 120 rpm for 1 minute.Then the sample was stirred slowly at a slow stirring speed of 30 rpm for a predetermined time (10, 20, and 30 minutes).After the stirring process, the samples were sedimented for 30 minutes.

Characteristics of well water
The well water located in one of the houses in Graha Indah, Balikpapan City has a depth of up to 40 metres.The results of preliminary tests on the pollution parameters are listed in Table 2.According to Table 2, it is known that the pollutant parameters in the well water still exceed the quality standards set in the Regulation of the Minister of Health of the Republic of Indonesia No. 32 of 2017.One of the causes of high turbidity in well water is the presence of dissolved solids such as clay, organic matter, plankton, and other small particles [8].High levels of Total Dissolved Solids (TDS) in well water indicate the influence of rock weathering, soil runoff, and household waste.High TDS is also influenced by chloride, which is commonly found in seawater [9].The chloride concentration value in the well water reached 1300 mg/l.
Iron metal concentration in well water exceeds the limit of quality standards that have been regulated.The iron metal content is caused by the flow of rainwater that seeps through the soil surface before reaching the well [10].In addition, the pH value of the well water is also not in accordance with the clean water quality standards which should range from 6.5 to 8.5.

Optimisation of pH
The research was performed with pH variations of 5, 6, 7, and 8 in an attempt to determine the optimum pH of well water in the coagulation and flocculation process.These results can be seen in Figure 1 and the change in pH value is shown in Figure 2. 1 shows the analysis results of determining the optimum pH value using LB-HCl.The initial turbidity value of the well water was 424 NTU with an initial pH value of 6.49.After the jar test, it was found that the optimum pH value for LB-HCl was 8 with a turbidity removal efficiency of 93%.Similar results were obtained for LB-H2O, with an optimum pH of 8 and a turbidity removal efficiency of 92%.These results indicate that pH 8 is the most optimal pH to remove the turbidity level of well water using both types of coagulants.As seen in Figure .3, the addition of LB-HCl coagulant to well water resulted in a considerable decrease in turbidity value.With an initial turbidity value of 424 NTU, there was a considerable decrease in turbidity value of 96.99%, resulting in a final turbidity value of 12.75 NTU at a dose of 0.5 ml and a stirring time of 10 minutes.Previous research also showed that the addition of LB-HCl coagulant can remove turbidity values with removal efficiency between 59.23% to 85.15% [12].As shown in Figure .6 3, the addition of LB-HCl coagulant to well water resulted in a significant decrease in turbidity values [13].HCl solution also plays a role in increasing polygalacturonic acid levels and protein levels extracted in Aloe vera, thereby increasing the efficiency of Aloe vera as a coagulant [14].In this study, it was found that the turbidity removal efficiency decreased in line with the increase in coagulant dose.This is because a larger amount of coagulant can cause the formation of flocs that are not optimal, so that the turbidity value increases compared to the turbidity value at the optimum dose [4].The effect of LB-H2O dosage and slow stirring time on turbidity is shown in Figure 4. significant decrease with a turbidity value of 34.95 NTU and a removal efficiency of 91.76% at a dose of 0.5 ml and a stirring time of 10 minutes.This decrease in turbidity is caused by polygalacturonic acid contained in Aloe vera which acts as a coagulant to bind flocs in well water [15].The results also showed that larger doses and longer stirring times did not significantly increase the effectiveness of the coagulation process [16].The results showed an insignificant decrease in the TDS parameter after the addition of LB-HCl coagulant.The lowest TDS value occurred at a dose of 0.5 ml and a slow stirring time of 20 minutes, with a value of 1912 mg/l and a removal efficiency of 8.05%.Whereas at a slow stirring time of 10 minutes and 30 minutes there was no significant decrease in TDS.This can be caused by the floc formation process that is not optimal at 10 minutes, as well as the occurrence of floc saturation at 30 minutes due to slow stirring that is too long [17].The effect of LB-H2O dosage and slow stirring time on TDS is shown in Figure.After adding LB-H2O coagulant to the well water, the final results of the TDS parameter were obtained which experienced an insignificant decrease and even an increase in the TDS value.Figure 6 IOP Publishing doi:10.1088/1755-1315/1312/1/0120079 shows that the TDS value has the highest removal at a dose of 0.5 ml and a slow stirring time of 10 minutes, but the TDS removal efficiency has only reached 3.09%.The decrease in TDS value is due to the positive charge on the Aloe vera coagulant suspension that reacts with the negative charge in well water, thereby being able to bind dissolved particles in the water [18].While at a slow stirring time of 20 minutes, there was an increase in the TDS value to 2,823 mg/l.The increase in TDS value at doses of 1 and 1.5 ml is due to excessive coagulant levels which cause the re-formation of colloidal particles in the solution, resulting in increased TDS levels.According to Figure .7, the final result of iron metal parameters after the addition of LB-HCl coagulant has changed.With an initial value of iron metal concentration of 1.072 mg/l, the largest removal occurred at a dose of 1 ml and a slow stirring time of 10 minutes with a removal of 0.313 mg/l and a removal efficiency of 70.85%.In this study, a dose of 1 ml with a slow stirring time of 10 minutes was declared the optimum dose.This is because in the addition of this dose, there is a change in the charge of the well water which causes a force of attraction between particles.As a result, the particles can bind effectively, so that all particles in the well water can be absorbed properly.While at other doses and stirring times it can be said that it is not optimal because the addition of positive charges that occur is still less or exceeds the optimum limit.So that the particle charges contained in the well water still reject and cannot bind perfectly to the colloidal particles of well water [19].The increase in iron metal values at a slow stirring time of 20 minutes is due to LB-HCl which is acidic so that iron metal can be dissolved [20].The effect of LB-H2O dosage and slow stirring time on pH is shown in Figure 8.Based on Figure .8, the final results of iron metal parameters after the addition of LB-H2O coagulant showed an increase.Based on the initial value of iron metal concentration of 1,072 mg/l, the largest removal occurred at a dose of 1.5 ml and a slow stirring time of 20 minutes with a removal of 1,004 mg/l and a removal efficiency of 6.39%.%.The increase in the value of iron metal is because Aloe vera contains polygalacturonic acid which causes Aloe vera to be acidic [4].In these acidic conditions, iron metal becomes dissolved and increases [20].

Analysis of the effect of dosage and slow stirring time on well water characteristics
Based on the test results using the one-way ANOVA method for parametric data and the Kruskal-Wallis method for non-parametric data, a significance value will be obtained.If the significance value > 0.05, it means that there is no significant difference and influence, so H0 is accepted and H1 is rejected.However, if the significance value <0.05, it means that there is a significant difference and influence, so H0 is rejected and H1 is accepted.The following are the analysis results for each parameter listed in Table 3.Based on the significance values obtained on the parameters of the test results with LB-HCl, the dose factor found that there was no effect on the parameters of turbidity, TDS and Fe metal.As for LB-H2O, there is no difference and influence on TDS and Fe metal parameters while there is a difference and influence on turbidity parameters.
Meanwhile, for the time factor with LB-HCl, there is a difference and influence on turbidity, TDS and Fe metal parameters, while for LB-H2O there is no difference and influence on turbidity and Fe metal parameters while there is a difference and influence on TDS parameters.

Conclusion
Based on the research results, it can be concluded that LB-HCl has a removal efficiency of turbidity, TDS and iron metal of 96.99%, 8.05%, 70.85% respectively.Meanwhile, LB-H2O has a removal efficiency of turbidity, TDS and iron metal of 91.76%, 3.09%, 6.39, respectively.
In LB-HCl, the coagulant dose did not significantly affect the removal efficiency of turbidity, TDS and Fe metal parameters.However, the slow stirring time variable had an effect on the removal of the three parameters.Meanwhile, in LB-H2O, the dosage only affected the turbidity parameter and the variable slow stirring time only affected the TDS parameter.

Figure 1 .
Figure.1 shows the analysis results of determining the optimum pH value using LB-HCl.The initial turbidity value of the well water was 424 NTU with an initial pH value of 6.49.After the jar test, it was found that the optimum pH value for LB-HCl was 8 with a turbidity removal efficiency of 93%.Similar results were obtained for LB-H2O, with an optimum pH of 8 and a turbidity removal efficiency of 92%.These results indicate that pH 8 is the most optimal pH to remove the turbidity level of well water using both types of coagulants.

Figure 2 . 5 3. 3 .
Figure 2. Changes in pH Value in pH Optimisation Figure.2 displays the results of changes in pH value when well water is treated with LB-HCl and LB-H2O.This is because in Aloe vera there are polyelectrolyte polymers containing carboxyl, hydroxyl and amide groups.The presence of carboxyl and hydroxyl groups causes the polyelectrolyte solution to be negatively charged and the amide group causes it to be positively charged.Therefore, Aloe vera coagulant is amphoteric so that it can work in acidic and alkaline condition[11].

Figure 3 .
Figure 3.Effect of LB-HCl Dosage and Slow Stirring Time on Turbidity; (a) Final Turbidity Value; (b) Removal Efficiency

Figure 4 .
Figure 4. Effect of LB-H2O Dosage and Slow Stirring Time on Turbidity; (a) Final Turbidity Value; (b) Removal Efficiency In Figure.4, it can be observed that the final result of the turbidity parameter after the addition of LB-H2O coagulant shows a downward trend.With an initial turbidity value of 424 NTU, there was a

3. 3 . 2 .
Effect of dosage and slow stirring time on TDS.The effect of LB-HCl dosage and slow stirring time on TDS can be shown in Figure.5

Figure 5 .
Figure 5.Effect of LB-HCl Dosage and Slow Stirring Time on TDS (a) Final TDS Value; (b) Removal Efficiency 6.

Figure 6 .
Figure 6.Effect of LB-H2O Dosage and Slow Stirring Time on TDS: (a) Final TDS Value; (b) Removal Efficiency

3. 3 . 3 .
Effect of dosage and slow stirring time on iron metal (Fe).The complete effect of dosage and slow stirring time on iron metal can be observed in Figure.7 below.

Figure 7 .
Figure 7. Effect of LB-HCl Dosage and Slow Stirring Time on Fe Metal: (a) Final Fe Metal Value; (b) Removal Efficiency

Figure 8 .
Figure 8.Effect of LB-H2O Dosage and Slow Stirring Time on Fe Metal (a) Final Fe Metal Value; (b) Removal Efficiency

Table 1 .
Research Independent Variables

Table 2 .
Characteristics of Well Water Regulation of the Minister of Health of the Republic of Indonesia No. 32, 2017

Table 3 .
Statistical Analysis Results of Pollutant Parameters