Treatment of Contaminated Water Collected from River Getsi Using Enhanced Natural Coagulant Prepared from Chrysophyllum Albidium Seeds

Paul Ocheje Ameh ^1,* , Joseph Ameh ², Amina Bello Mahmoud ¹, Adabiyya Rabiu Shuaib ¹, Aroh Augustina Oyibo ¹, Fadeyi Sulayman Olusola ¹, Isaiah Blessing Imeh ¹, Egbe Hope Thankgod ¹, Ajagbonna Damilola Lilian ¹, Bitrus Nehemiah ¹

1. Department of Chemistry, Nigeria Police Academy, Wudil, P. M B. 3474, Kano State, Nigeria

2. Department of Medical Biochemistry, Nile University of Nigeria Abuja, Nigeria

* Correspondence: Paul Ocheje Ameh 

Academic Editor: Md Tabish Noori

Special Issue: Advanced Treatment for Water or Wastewater

Received: March 31, 2025 | Accepted: July 07, 2025 | Published: July 15, 2025

Adv Environ Eng Res 2025, Volume 6, Issue 3, doi:10.21926/aeer.2503026

Recommended citation: Ameh PO, Ameh J, Mahmoud AB, Shuaib AR, Oyibo AA, Olusola FS, Imeh IB, Thankgod EH, Lilian AD, Nehemiah B. Treatment of Contaminated Water Collected from River Getsi Using Enhanced Natural Coagulant Prepared from Chrysophyllum Albidium Seeds. Adv Environ Eng Res 2025; 6(3): 026; doi:10.21926/aeer.2503026.

© 2025 by the authors. This is an open access article distributed under the conditions of the Creative Commons by Attribution License, which permits unrestricted use, distribution, and reproduction in any medium or format, provided the original work is correctly cited.

1. Introduction

As the world population increases, the consumption of water and water treatment become critical. Increase in various human activities has resulted in the discharge of huge quantities of hazardous inorganic and organic pollutants into aqueous systems [1]. Many freshwater reservoirs are becoming unsuitable for daily usage owing to the untreated disposal of wastewater [2]. The management of quality drinking water and maintaining pollutant-free water has become a crucial task in order to prevent any diseases and further avoid the destruction of the environment [3]. Available methods for wastewater treatment include sedimentation, flotation, filtration, precipitation, electro-floatation, adsorption, coagulation, disinfection, air stripping, carbon adsorption, ion exchange, and reverse osmosis [2,3,4].

The use of coagulants for the removal of colloidal particles and organic matter in water and wastewater treatments has received considerable attention owing to their high impurity removal efficiency [5]. Several chemicals-based coagulants such as iron oxide salts, aluminum sulfate (alum), ferrous sulfate, ferric chloride, and ferric chloro-sulfate, in addition to various polymer nanocomposites, have been evidenced in water treatment applications [5,6]. However, the use of these chemical-based coagulants is limited in developing countries like Nigeria because of the high costs of their importation, low availability, and has been reported to have neurotoxic/strong carcinogenic effects. Hence, special attention is now being given by researchers to environmentally friendly coagulants as they have been found to be cheap, do not produce treated water with extreme pH, and are highly biodegradable [7]. Natural coagulants successfully produced from Moringa oleifera, Dacryodes edulis, peanut seeds, Nirmali seed, and mesquite bean for wastewater treatment have been reported [7,8,9,10,11]. The existing studies in the literature do not give comprehensive facts in terms of the complete physicochemical properties of these natural coagulants. There is also a need to search for the native materials which can be used for water purification, as these can provide technology near the point of use that can be adapted by communities.

In the quest to search for other cost-effective and more environmentally acceptable alternative coagulants from natural resources while solving environmental waste problems, we present in this study enhanced coagulants produced from Chrysophyllum albidium fruit seed. Chrysophyllum albidium fruit, also known as African Star Apple fruit, is widely consumed in Northern Nigeria, and the seeds from the fruit, which constitute a nuisance to the environment during the dry season, could be converted to wealth in wastewater treatment.

This study therefore was conducted to investigate the removal performance of contaminated water using modified and unmodified Chrysophyllum albidium fruit seed as a potential natural coagulant, to characterize Chrysophyllum albidium fruit seed as coagulant based on physical, chemical, and morphological properties and to investigate the effects of pH, dosage, sedimentation rates and mixing speed on the removal performances of contaminants using the fruit seed as the natural coagulant. The contaminated water being treated in the study was collected from River Getsi, which is located in the Northern Nigerian state of Kano (latitude 12040I and 10030IN, and longitude 7040I and 9030IE), and normally collects all the wastes from Bompai Industrial Area [12]. The River water, which is used for irrigation and domestic purposes, is characterized by a high level of metal contaminants [12,13].

2. Materials and Methods

2.1 Chemicals and Glassware

All glassware was cleaned and rinsed with detergents and immersed in 25% nitric acid, and finally rinsed with deionized water. In the preparation of reagents, chemicals of analytical grade were used with deionized water.

2.2 Coagulant Collection and Preparation

The fresh Chrysophyllum albidium fruit was obtained from Sabon Gari market in Kano State, Nigeria, and was de-fleshed using a clean stainless steel knife to obtain the seeds. The seeds were washed several times with distilled water, sun dried for a week, sorted to remove bad ones, and thereafter subjected to oven drying at 80°C for 12 hours to remove moisture. The dried seeds were then crushed into powder form using an electric motor connected to a crusher and sieved using a 2 mm mesh sieve. The resulting powder obtained was thereafter placed in an air-tight container and labeled unmodified Chrysophyllum albidium seed coagulant (UCASC).

The modified Chrysophyllum albidium seed coagulant (MCASC) was produced using a green synthesis approach that involved microwave treatment as reported by [14]. During the preparation of MCASC, some of the UCASC powders earlier produced were treated numerous times using a microwave oven (GE82V model, Samsung) at an energy of 700 W for 30 seconds, followed by chilling and grinding [14].

2.3 Characterization

2.3.1 Proximate and Phytochemical Screening Analysis

Proximate composition (Moisture, Ash, Fat, Crude Fibre, Crude Protein, Nitrogen Free Extracts, and Carbohydrate content) and phytochemical screening analysis of the coagulants were carried out following the method as described by AOAC [15].

2.3.2 Surface Charge

The surface charge of the coagulants was measured in triplicate using the colloidal titration method. Initially, 2.5 g of powder coagulant was mixed into 200 mL of distilled water for three minutes. The resulting solution was then diluted to 12500 mg/L as a stock solution and poured into a conical flask. 8.0 mL of 0.25 g/L polydiallyldimethyl ammonium chloride (PDAC) was added (to show the presence of cationic polyelectrolyte) to the stock solution and mixed thoroughly, after which a few drops of 0.05 g/L toluidine blue solution (indicator) were added. The solution was then titrated with 0.2027 g/L polyvinyl sulfate potassium (PVSK) solution (to show the presence of an anion) until the color changed from blue to pink or purple. The blank sample with only distilled water was repeated as a control parameter. The surface charge was computed using Equation 1.

\[ \text { Surface charge}\left(\frac{\mathrm{meq}}{\mathrm{~g}}\right)=\frac{(A-B) \times N}{V \times C} \times 100 \% \tag{1} \]

Where A is the Volume of PVSK titrated to the sample in mL; B is the Volume of PVSK titrated to the blank sample in mL; N is the Normality of PVSK in eq/L; V is the coagulant stock solution volume in mL, and C is the coagulant stock solution concentration (mg/L).

2.3.3 Scanning Electron Microscopy Analysis

Scanning Electron Microscopy (Model: JSM-5600 LV, TOKYO) analysis was carried out to observe the morphological properties of the synthesized coagulants. A small portion of the sample was placed in a metal stub using a two-sided adhesive tape and coated with a fine layer of gold using a sputter gold coater. The micrographs were observed with 5.0 magnification at an accelerating voltage of 15 kV under the scanning electron microscope.

2.3.4 Fourier Transform Infra-Red (FTIR) Analysis

The attached functionalities of both MCASC and UCASC were characterized using Shimadzu FTIR-8400S Fourier transform infrared spectrophotometer. The sample for analysis was prepared by mixing the synthesized coagulants with KBr to make it conductive. The analysis was done by scanning the sample through a wave number range of 0-4500 cm^-1.

2.3.5 Powder X-Ray Diffraction (PXRD) Study

The structural pattern of the synthesized coagulants was analyzed using a Panalytical X’Pert Pro X-ray diffractometer, Netherlands, equipped with a Cu-Kα 1.54 Å monochromatic source, operating at a voltage of 40 kV and a filament current of 40 mA. The samples were placed on a flat plate while intensity data were collected as a function of the Bragg angle, θ, in the range 2θ = 10° to 70° with a step size of 0.013°.

2.4 Collection of Water Samples

The initial raw or untreated water samples used in this study were collected from River Getsi (See Figure 1) in May 2024 using the composite sampling method as described by the American Public Health Association [16]. The composite water samples were preserved in clean high density polyethylene container and kept in cold environment to retard both the biological and chemical changes that could occur before its characterization and jar test experiments.

Figure 1 River Getsi.

2.5 Analysis of Physicochemical Parameters

All the instruments used for the analysis of physicochemical parameters were initially calibrated using the manufacturer’s standard. Physicochemical parameters such as colour, temperature, pH, turbidity, Chemical Oxygen Demand (COD), Total dissolved solids (TDS), Dissolved Oxygen (DO), phosphate, chloride, nitrate, and sulphate of the water samples were evaluated to ascertain the extent of contamination prior to and after coagulation. The phosphate, chloride, nitrate, and sulphate were evaluated using the method as described by the American Public Health Association [16].

The colour of the water sample before and after treatment was measured using a HARCH DR/2000 spectrometer. The pH and temperature of the water samples were determined using a Jenway 3510 pH meter and a digital thermometer, respectively. The conductivity and TDS tests were performed using the HACH Sension 5 conductivity/TDS meter. Dissolved oxygen (DO) and biological oxygen demand (BOD) were determined using a HANNA instrument (H198130, Denver, USA). The heavy metal content of the water samples was evaluated using a Thermo Elemental Inductively Coupled Plasma-Mass Spectrometer (X Series II).

2.6 Treatment of Contaminated River Water Samples Using the Prepared Coagulant

Determination of the efficiency of the synthesized coagulants in the treatment of the contaminated river water was performed using the conventional Jar test Apparatus (Cintex Flocculator) as described in the literature [17]. The experiments were carried out in batches and in triplicate, and the results were represented as averages. Coagulation was evaluated based on its ability to reduce the contaminants in the water sample. The contribution of coagulants dosage (0.1-0.6 g/L), temperature (303-333 K), mixing speed (20-240 rpm), and pH (2-12) on coagulation was investigated. In each case, the percentage removal efficiency of the parameters was computed using equation 2.

\[ \text { Percentage removal efficiency}=\frac{T_{2}-T_{1}}{T_{2}} \times 100 \% \tag{2} \]

Where T₁ and T₂ are respectively the initial (before treatment with coagulant) and final value (before treatment with coagulant) of the parameter being evaluated.

3. Results and Discussion

3.1 Coagulant Characterization

3.1.1 Proximate Analysis of the Prepared Coagulant

The prepared unmodified Chrysophyllum albidium seed coagulant (UCASC) and modified Chrysophyllum albidium seed coagulant (MCASC) were analyzed for their proximate composition, which included bulk density, moisture content, crude fat, crude protein, carbohydrate content, crude fiber, and ash content. The results obtained are as reported in Table 1. It can be seen from the result presented that the percentage moisture content of UCASC and MCASC was found to be 7.72% and 5.87% respectively. These values were slightly lower than 9.39% and 9.0% reported by Damilola et al. [18] and Akubor et al. [19], respectively. The values are also lower than those reported for Moringa oleifera seeds by Ijarotimi et al. [20] and Olagbemide and Alikwe [21]. The low moisture content of UCASC and MCASC, according to Akin-Osanaiye et al. [22], would enhance their storage stability by inhibiting mould growth, and decreasing moisture-dependent biochemical reactions. This implies that the prepared coagulants in this study have a good shelf life and can be stored for a long time.

Table 1 Proximate composition of UCASC and MCASC.

It has been reported widely in literature that the ash content of a sample is related to the presence of inorganics with different charges and often gives the amount of mineral present in that sample [23]. According to Olagbemide and Alikwe [21], the presence of multi-charged ions in plant seed extracts usually aids the coagulation process in water treatment. Also, studies have proven that the addition of ions can help to reduce residual turbidity [23]. The values of the ash content of the studied coagulants were found to be 3.13 and 3.27, respectively, for MCASC and UCASC. These values are not significantly different from the ones reported in the literature for good natural coagulants [21].

The observed fat content values of UCASC and MCASC (5.12% and 4.97% respectively) were significantly lower compared with those reported for Moringa oleifera seed (38.67%), Duncan mango seed (15.51%), and African pear seed (16.93%) [21]. Studies have shown that high fat content in seeds tends to hinder their coagulation capability, and seeds with lower fat content are more desirable for water treatment applications [24]. This suggests that both UCASC and MCASC will be good coagulants for water treatment. This also implies that a modified form of the prepared coagulant, i.e., MCASC, may be a better coagulant than UCASC since it has lower fatty content.

The percentage crude fibre content (insoluble carbohydrate) of MCASC and UCASC was found to be 2.07 and 2.11% respectively. Although crude fibre has not been reported to enhance the coagulation process, lower values in seeds could be better as it’s not soluble in water, hence might not have an impact on the coagulation process [21].

Protein has been reported to be an active coagulating agent, and its values greatly influence the coagulation capability of seeds [5]. The prepared coagulants were found to contain an appreciable amount of crude protein, with MCASC and UCASC having 10.87% and 10.42% respectively. These values are significantly higher than 4.50% previously reported by Akubor et al. [19]. The Nitrogen Free Extracts (NFE) of the prepared coagulants were estimated to determine the amount of soluble carbohydrate (starch and sugar) present in them. The percentage of NFE in MCASC and UCASC was found to be 73.15% and 72.86% respectively. The high nitrogen-free extracts in these prepared coagulants imply that they contain a high amount of starch and could be advantageous to the coagulation process (as the number of active sites available for particle adsorption will be increased). Sotheeswaran et al. [7] have reported starch to be the primary coagulation agent during water treatment, where it binds contaminants through adsorption and an interparticle bridging mechanism. The total carbohydrate content, which was obtained by adding the NFE values to the crude fibre was found to be 75.22% and 74.97% for MCASC and UCASC, respectively.

3.1.2 Phytochemical Analysis of the Synthesized Coagulants

The results of phytochemical analysis of the synthesized coagulants are given in Table 2. The result presented indicated that coumarins, glycosides, flavonoids, starch, alkaloids, phenols, tannins, and saponins are present in both MCASC and UCASC. Steroids were, however, not detected in both coagulants. The presence of tannins in natural coagulants has been reported in literature to enhance turbidity and colour removal from water sources owing to the use of a weakly basic polymer which is formed by reacting tannins with formaldehyde and amino ethanol [25]. Nwokonkwo [9] has suggested that saponins, flavonoids, coumarins, and phenols possess antibacterial potential against human pathogens. They act by attacking organisms attached to suspended particles in water, causing turbidity.

Table 2 Phytochemical screening of MCASC and UCASC.

3.1.3 Surface Charge of the Synthesized Coagulants

The surface charges of MCASC and UCASC were found to be +6.8 and 6.3 meq/g, respectively, implying that the synthesized coagulants are positively charged or highly cationic. The positive surface charge can be attributed to the presence of soluble proteins in the coagulants. The values obtained are similar to those reported for banana peels (+6.4 meq/g) by Pathak et al. [25]. They are also higher than those reported for orange peels (+0.19 meq/g) and citrus peels (+0.25 meq/g) by Calatayud et al. [26].

According to Calatayud et al. [26], acidic surface usually favors the attraction of anionic contaminants, whereas the basic surface favors the attraction of cationic contaminants. For this study, both MCASC and UCASC are considered highly cationic and thus can be helpful in treating anionic pollutants.

3.1.4 Scanning Electron Microscopy (SEM) Study

Figure 2a and 2b show the SEM micrographs of MCASC and UCASC, respectively. A closer examination of the figures indicates the micrographs have porous, round, and rough granular structures that can favour adsorption and bridging of colloidal particles, thereby promoting the sedimentation of particles during water purification.

Figure 2 SEM micrographs of (a) MCASC and (b) UCASC.

The of MCASC-, the modified form of the coagulant (Figure 2a), appeared to have particles that are more homogeneous and smaller in size. This means that the microwave treatment of Chrysophyllum albidium seed powder during its modification has significantly enhanced its surface morphology as well as the particle size. Adeel et al. [27] have reported that microwaves are capable of creating surface fractions on smooth surfaces, resulting in their breaking and disinterest, despite the slight heating in each treatment, which accounts for the negligible decrease in particle size.

Thus, from these features observed from the SEM study, it is said that the both coagulants have enough morphological profile for adsorbing other impurities.

3.1.5 X-Ray Diffraction (XRD) Analysis

Figure 3 gives the XRD patterns obtained for both MCASC and UCASC. Intensive diffraction peaks were observed at 2θ = 16.1° and 22.2°, corresponding to crystal planes of (100) and (200), respectively, indicating the compounds’ crystallinity and amorphous nature [28].

Figure 3 XRD patterns of MCASC and UCASC.

The exhibited XRD patterns also indicate that the prepared coagulants do not have any impurities and are in pristine forms [28]. These features might be responsible for the adsorption of pollutants onto the coagulant surface [29]. The similarity in the peaks exhibited by MCASC and UCASC implies that the modifications did not change the coagulant crystalline nature.

The size of the prepared coagulant particles was estimated using Scherrer's formula,

\[ \mit{D}=\frac{0.9\alpha}{\beta\mathrm{cos}\theta} \tag{3} \]

Where D is the crystallite size in nm, α is the radiation wavelength (0.15401 nm for Cu-Kα), β is the bandwidth at half height of the highest peak, and θ is the diffraction peak angle [30]. From the equation, the sizes of MCASC and UCASC particles were evaluated to be 125 nm and 157 nm, respectively.

The smaller particle size of MCASC is expected as the microwave treatment of the coagulant will have modified the structure and properties of the natural material.

3.1.6 Fourier Transform Infrared Spectroscopy (FTIR) Study

FTIR study is one of the methods that can be used to identify functional groups that are available in the coagulants. The coagulation-flocculation process is an adsorption process that is facilitated by the presence of hetero atoms or suitable functional groups [2]. The FTIR spectra obtained for UCASC and MCASC are given in Figure 4a and 4b, respectively. The frequencies and functional group assignments that are associated with the absorption of IR are presented in Table 3.

Figure 4 FTIR spectra of (A) UCASC and (B) MCASC.

Table 3 Frequencies and percentage transmittance of IR absorption by MCASC and UCASC.

The spectra revealed the presence of N-H stretch, C-N stretch, C-O stretch, C-C stretch of aromatics, -C≡C stretch, -C≡N stretch, H-C=O stretch, C-H stretch, aromatic ring and O-H stretch in the studied coagulants. Functional groups like the O-H stretch of alcohols and phenols, N-H stretching of amino compounds and the carboxyl, C=O group when present in substances have been reported to usually aid coagulation-flocculation processes [14]. Therefore, we can say that the coagulation efficiency of UCASC and MCASC during water treatment can partly be attributed to the presence of suitable functional groups, hetero atoms, and π π-electrons. The observed difference in the position of the observed peaks in MCASC when compared to UCASC may be a result of the modification of the latter by microwave oven treatment.

3.2 Physicochemical Evaluation of Water Collected from River Getsi

Preliminary analysis was carried out to evaluate the physicochemical properties of the water samples collected from the River Getsi with a view to ascertaining the level of contamination before treatment. The average temperature of the River water was found to be 37°C, which is higher than the permissible limit of 30°C set by the National Environmental Standards and Regulations Enforcement Agency [31] and the World Health Organization [32]. Higher temperature induces chemical and biological reactions in wastewater. It will also affect the solubility of oxygen and produce a foul odour due to anaerobic responses [33]. This may account for the foul smell of the water from the River Getsi.

The pH of the River water was found to be 6.1. Yakasai et al. [34] have reported that water containing high organic content tends to be acidic. The slight acidity of the water observed may be attributed to high organic content from the urban and domestic runoff into the water body. Colour is the basic and most obvious indicator in water pollution, and it is a worldwide accepted primary pollutant in drinking water [1]. The colour of the River water selected for treatment in the present study was brownish yellow, and when measured, it gave a value of 195 TCU, which was beyond the limits of 15 TCU given by WHO for drinking water [32]. The TSS and turbidity values were estimated to be 5582 mg/L and 34.81 NTU, respectively, which are also beyond the WHO permissible limit of 2000 mg/L and 5 NTU, respectively [32]. The BOD and COD, which indicate the level of biodegradation of organic materials and the amount of organic compounds in water, respectively, were found to be 275.2 and 386.2 mg/L. The high values of BOD and COD obtained in the study point to the deterioration of the water quality, which might have been caused by the discharge of industrial effluent and domestic sewage into the River Getsi [35]. The amount of nitrates in the water was found to be 57.22 mg/L, which is above the WHO limit of 50 mg/L. The high nitrate levels obtained may be from agricultural runoff contributing to pollution of the river water [36].

The concentration in mg/L for Cu, Pb, Cd, Zn, Cr, and As ions determined in the River water were found to be 3.10, 5.95, 0.108, 0.007, 4.850, 0.083, and 0.131, respectively. These values, with the exception of that obtained for Zn, exceeded the WHO permissible limit recommended for healthy/drinking water [32]. This exceedance of the stipulated standard could come from the fact that River Getsi receives domestic runoff and industrial waste waters [37]. Higher concentration of metals in the water compared to the WHO standard is consistent with the result obtained by Jamila and Sule [12], where the range of concentrations measured exceeded the permissible limit set by the World Health Organization.

3.3 Determination of Optimum Performance of Coagulants

The optimum performance of the coagulants was determined by investigating the effect of coagulant dosage, temperature, mixing speed, and pH on the reduction of TSS, COD, Pb²⁺, Cd²⁺, and Ni²⁺ in the contaminated water.

3.3.1 Effect of Dosage on Coagulation

Dosage was one of the most critical parameters that were established to influence the mechanism of coagulation. It is imperative to determine the optimum dosage of coagulants used for water treatment so as to reduce the production of sludge, minimize dosing cost, and achieve an optimal treatment efficiency [38]. The effect of coagulant dosage was analyzed at pH 7,200 rpm of mixing rate for 10 minutes and 30 minutes of settling time for a range of MCASC and UCASC dosages (0.1, 0.2, 0.3, 0.4, 0.5, and 0.6 g/L). The removal efficiency of the target parameters under the effect of the coagulants dosage was evaluated, and the results obtained are presented in the form of plots as indicated in Figure 5A and 5B.

Figure 5 Effect of (A) UCASC and (B) MCASC dosage on coagulation.

From the Figures, it can also be seen that the coagulation capacity of both MCASC and UCASC increases with an increase in the mass of coagulants until it reaches a dose of 0.4 g, and thereafter decreases with any further increase in the amount of coagulants. This implies that higher doses (above 0.4 g) of prepared coagulants, when used in processing, may inhibit and reduce flocculation efficiency due to precipitation in large quantities. The percentage removal efficiency of the various parameters by the unmodified coagulant (UCASC) was found to be lower than that obtained by the modified form (MCASC), which further supports earlier results that the modification of the coagulant might have increased its coagulation capacity.

3.3.2 Effect of pH Variance

The pH is another important factor that should be considered when measuring coagulation efficiency, as the surface charge of coagulants may be affected by the pH during the coagulation process [39]. Coagulants with a low surface charge might cause the slow growth of floc particles, thus leading to low removal performance in water treatment [40].

Table 4 presents the percentage removal of the target parameters from the river water by both UCASC and MCASC at various pH levels (2-12). From Table 4, it can be seen that the coagulation efficacy significantly increased from pH 2 and rapidly decreased after pH 8. Based on the results presented in the table, the best pH value to remove the river water contaminants was at pH 8. This implies that the molecules of the coagulants have a greater ability to absorb at pH 8, which may be as a result of the neutral electrical charge of ammonia-nitrogen that the coagulant compound contains, as revealed from the phytochemical/FTIR study. This observed trend can also be attributed to the material's intricate structure, which may include amphoteric ions [41]. MCASC contributed the highest contaminant removal from the river water, while UCASC had the lowest coagulation activity.

Table 4 Effect of pH on the removal of the various contaminants by UCASC and MCASC.

3.3.3 Effect of Temperature

The contaminants removal was studied at different temperatures of 303, 313, 323, and 333 K at a pH of 8 and the coagulant dosage of 0.4 g/L. The highest removal efficiency was obtained at the lowest temperature (303 K), as can be seen from the results presented in Figure 6. The reduction in pollutant removal with increasing temperature may be due to the formation of random motion of colloidal particles caused by the increase of kinetic energy, which interferes with the attachment of particles onto the coagulants to form flocs and reduction in floc sizes [42].

Figure 6 Effect of temperature on the removal of the various contaminants by UCASC and MCASC.

3.3.4 Effect of Mixing Speed

The effect of mixing speed on the removal of the various contaminants by UCASC and MCASC at optimally coagulant dosage was determined by repeating the coagulation-flocculation protocol at several mixing speeds (30, 60, 90, 120, 150, 180, 210, and 240 rpm), and the results obtained are given in Table 5. It can be observed that the percentage removal of the various studied parameters that contaminated the river increased with mixing speed up to 210 rpm and thereafter decreased. This trend is similar to the one reported by Afangideh [17] for watermelon seeds.

Table 5 Effect of mixing speed on the removal of the various contaminants by UCASC and MCASC.

3.4 Treatment of the Contaminated Water from River Getsi with Coagulants at Optimal Conditions

The water from River Getsi does not represent good quality drinking water due to the fact that most of the physicochemical parameter values, as reported above (Section 3.2), were more than the WHO specified guidelines recommended for healthy/drinking water. The River water was thereafter subjected to treatment using MCASC and UCASC at optimum conditions (at solution pH of 8, coagulant dosage of 0.4 g/L, solution temperature of 303 K, mixing speed of 210 rpm and settling time of 30 minutes) and their impacts were examined.

Table 6 shows the physical and chemical characteristics of the sampled river water before and after the treatment with the coagulants at optimum conditions.

Table 6 Physico-chemical parameters of River Getsi water before and after treatment.

A closer look at the results presented indicated that both MCASC and UCASC have tremendous potential to treat polluted water. Both UCASC and MCASC were found to reduce the amount of dissolved and suspended solids in river water, as well as reducing the amount of chemical and biochemical oxygen needed. For instance, the turbidity of the river water when the unmodified and modified Chrysophyllum albidium seed coagulants were applied reduced from 30.81 to 2.91 (90.55%) and 1.02 (97.04%) for UCASC and MCASC, respectively. As revealed by the FTIR study and phytochemical study, the prepared coagulants (UCASC and MCASC) contain various groups of chemicals like phosphate, hydroxyl groups, and carboxylic acid, which may act as active hubs for water colour, total suspended solids, COD, and TDS removal.

The performance of the prepared coagulants in the removal of heavy metals from the sampled contaminated river water (evaluated from Table 6 by calculating the percentage removal using equation 2) followed the order: As > Fe > Cr > Cu > Cd > Zn > Pb. The differences in the uptake levels of the metal ions by the adsorbent can be explained in terms of their differences in the ionic size and atomic weight of the metal ions, their mode of interaction between the metal ions and the substrate [43].

MCASC (the modified form of the prepared coagulant that was subjected to microwave treatment) was found to perform better in terms of lowering all of the parameters when compared to UCASC. This improvement may be due to the microwave-treated particles having superior ion exchangeability and high porosity rather than non-treated particles of UCASC.

3.5 Comparison of Previous Coagulation Performance

The performance of MCASC was compared to alum (a chemical coagulant) in the removal of some of the water contaminant parameters at optimum conditions. MSCAS was selected for the comparison as against USCAS since it gave the best performance among the two prepared coagulants. Figure 7 shows the performance comparison between natural coagulant (MCASC) and chemical coagulant (alum).

Figure 7 Performance comparison between MCASC and alum.

The results showed that the natural coagulant acts as a better coagulant agent compared to alum. MCASC was found to remove almost 97.04%, 97.86%, 94.68%, 94.23%, and 90.81% of turbidity, TSS, TDS, COD, and BOD, respectively, as compared to 89.90%, 90.45%, 91.31% and 87.67% achieved by alum.

The efficiency of COD removal of MCASC in this experiment was considered high as compared to the maximum COD removal of bagasse at only 67% [44]. Compared to established natural coagulants such as Moringa oleifera, the COD removal obtained in this present study is still higher than the result conveyed by Kumar et al. [45] with 83.3% COD removal.

Table 7 further compares our findings to the results of other experiments conducted under various circumstances for several natural coagulants. From the Table, it is evident that the newly synthesized MCASC is more capable of reducing contaminants from wastewater and for the application under moderate process conditions.

Table 7 Coagulation performances of the MCASC and UCASC with different literature.

3.6 Cost Analysis

Economic assessment is another critical factor to consider as it influences the implementation of any newly developed material/technique. The method used for cost analysis in this study is as outlined by Tripathy and Kumar [53]. The coagulant cost was calculated based on the cost of the raw material, transportation, energy consumption, labour cost, coagulant optimum dosage, and the cost per kilo of each of the coagulants for 1 m³ of the treated water. The total cost for the preparation of 1 kg of MCASC was found to be $0.0006, while the estimated cost per m³ of treating the contaminated water using the same coagulant is USD $0.024. A kilo of Moringa oleifera seeds- a commonly used natural coagulant for water treatment, is currently sold at USD $1.40, while its cost of treating water per m³ has been reported to be USD $0.042 [54]. The price for alum, which is about $0.30-$0.50/kg, has an estimated cost of USD $0.05 per m³ [55,56]. The total operating cost in the ultrasonic synthesis of magnetic Moringa oleifera coagulant for the reduction of chemical oxygen demand in palm oil wastewater has been reported to be $12.05/kg [57]. Based on these facts, it can be said that the cost of water treatment using MCASC is found to be lower than some well-known coagulants. The coagulants produced in this study are less expensive due to a simple method of preparation and zero cost of some of their raw materials.

3.7 Mechanism of Action of the Prepared Coagulants

It is established from this study (See Table 6) that River Getsi contains a high amount of anionic contaminants like nitrate, chloride, and sulphates, as the values obtained exceeded the maximum permissible limits of the WHO. Jamila [12] in their study to assess the quality index of River Getsi irrigation water reported that the contaminants of the River water are anionic that might have resulted from various pollution sources like agricultural runoff, industrial discharge, and sewage. We have also discovered from the surface charge analysis of our coagulants (Section 3.1.3) that both MCASC and UCASC are highly cationic. The removal of the contaminants from the treated water may have taken place via adsorption and bridging, wherein the long chains of polymers (proteins, etc.) molecules of the coagulants interact with the charged impurities, forming bridges between them and culminating in macro flocs, which tend to settle faster (sedimentation).

The interactions between the anionic contaminant particles are anionic, and the cationic coagulating particles from the prepared coagulants may have resulted in an electrostatic attraction between them and cause adsorption, charge reversal, and the neutralization of contaminant particles. The flocs, which are generated from this interaction, start settling (sedimentation) and are easily removed from the water, thus treating the water.

4. Conclusion

The results and findings of this study reveal that natural coagulant prepared from Chrysophyllum albidium seeds has tremendous potential to treat contaminated water and is superior to alum (chemical coagulant). Coagulation performance of the unmodified and Microwave-modified Chrysophyllum albidium seed powder showed the same best conditions, which are 1.0 g/L of coagulant dosage, initial pH of 8, solution temperature of 303 K, mixing speed of 210 rpm, and 30 minutes of settling time. However, the removal efficiency of contaminants from the River water by the modified form was higher when compared to the unmodified form. The removal of the contaminants from the treated water may have taken place via adsorption and bridging, wherein the long chains of polymers (proteins, etc.) molecules of the coagulants interact with the charged impurities, forming bridges between them and culminating in macro flocs, which tend to settle faster (sedimentation). The costing assessment made in this study illustrates that the total cost in the synthesis of the coagulants used was lower than many reported good coagulants in the literature. This is attributable to the simple method of preparation, zero cost of raw materials, and lower energy consumption during its preparation.

Author Contributions

The research was conceived by Paul Ocheje Ameh. The characterization study was done by Paul Ocheje Ameh, Joseph Ameh, Amina Bello Mahmoud, Adabiyya Rabiu Shuaib, Aroh Augustina Oyibo, Isaiah Blessing Imeh, Egbe Hope Thankgod, Ajagbonna Damilola Lilian, and Bitrus Nehemiah. Paul Ocheje Ameh, Joseph Ameh, Fadeyi Sulayman Olusola and Egbe Hope Thankgod carried out the adsorption study. All authors wrote the first draft, revised, and edited the final manuscript.

Funding

The research work that generated this publication was sponsored by the Tertiary Education Trust Fund of Nigeria (TETFUND) through the Institution Based Research (IBR) grant with Dr Ameh Paul Ocheje as the Principal investigator (Grant number: TETF/ES/DR&D/CE/NP/WUDIL/IBR/2024/VOL.III/Serial No. 2).

Competing Interests

The authors declare no competing interests.

Data Availability Statement

The datasets used or analyzed during the current study are available from the corresponding author upon reasonable request.