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This study investigates the feasibility of a robust, low-cost tubular microfiltration ceramic membrane fabricated using a mixture of locally available Fuller's earth clay (FEC) and solid waste material, rice husk ash (RHA), to treat effluents generated by a local dairy and palm oil industries. Fabrication of the membrane was carried out by employing the extrusion method followed by sintering at a temperature of 850 °C. Raw materials were characterized using XRD, XRF, FTIR, TGA, and differential thermal analysis (DTA). The membrane that underwent sintering exhibits a 61% porosity level, 43.29 L/m2 h bar water permeability, 0.115 μm average pore size, and relatively good corrosion resistance. Further, the effect of different operating conditions, including pressure (1.03–2.41 bar) and cross-flow rate (30–150 Lph), on the microfiltration of both the wastewaters is studied. The membrane lowered the COD levels below the discharge limit (<200 mg/L) of the Central Pollution Control of India for both wastewaters. Finally, Hermia's fouling models were used to identify the fouling mechanism concerned.

  • Fuller's earth clay and rice husk ash were utilized to fabricate inexpensive tubular ceramic membranes.

  • The potentiality of the microfiltration membrane was assessed by treating dairy and oil industry wastewater.

  • Both the treated wastewater met the allowable limit chemical oxygen demand (COD) for discharge (<200 mg/L).

  • 99% of turbidity was removed from both dairy and palm oil industries’ wastewater.

ceramic membrane, extrusion, food industry effluents, Fuller's earth clay, membrane technology, wastewater treatment
FEC

Fuller's earth clay

RHA

Rice husk ash

HCl

Hydrochloric acid

NaOH

Sodium hydroxide

pH

Potential of hydrogen

BOD

Biological oxygen demand

COD

Chemical oxygen demand

XRD

X-ray diffraction

XRF

X-ray fluorescence spectroscopy

FTIR

Fourier transform infrared

TGA

Thermogravimetric analysis

DTA

Differential thermal analysis

SEM

Scanning electron microscopy

TSS

Total suspended solids

TDS

Total dissolved solids

Lp

Permeability

CF

Cake filtration

IPB

Intermediate pore blocking

SPB

Standard pore blocking

CPB

Complete pore blocking

SiO2

Silicon dioxide

Al2O3

Aluminum oxide

Fe2O3

Ferric oxide

K2O

Potassium oxide

TiO2

Titanium dioxide

CaO

Calcium oxide

SO3

Sulphur trioxide

Water is an indispensable resource crucial for all living beings' survival. To address the limited availability of usable water, treating wastewater is necessary to enhance water quality by eliminating the majority of the contaminants present in it (Belaid et al. 2009; Aitali et al. 2016). The dairy industry is often the leading contributor to food processing wastewater in many countries. It is a water-intensive sector and generates 2.5 times the quantity of processed milk, which contains significant contaminants such as chemical oxygen demand (COD), biochemical oxygen demand (BOD), suspended solids, fats, minerals, ammonia, and phosphates (Dibene et al. 2021). The COD must be lowered below 200 mg/L for disposing of treated water to comply with pollution regulations, as elevated COD concentrations in wastewater can lead to oxygen depletion in aquatic ecosystems, causing harm to aquatic life and disrupting the balance of ecosystems. Industrial sectors like petrochemical, food, textile, and leather have resulted in the large-scale production of oily wastewater. The permissible discharge limits are set at approximately 10 and 20 mg/L for inland water and marine coastal areas, respectively, to minimize environmental impact (Kumar et al. 2016b).

Membrane technology is becoming a promising method because of its ease of operation, cost-effectiveness, high stability, and minimal environmental impact while effectively removing pollutants from wastewater without any degradation or chemical additives (Croft et al. 2023; AitAli et al. n.d.). In recent years, ceramic membrane technology has become promising in treating industrial wastewater due to its excellent characteristics over polymeric membranes (Rani & Kumar 2021). They are primarily made of alumina, silica, titania, zirconia oxides, and silicon carbide, which are expensive. However, the essential quality of treated wastewater could be attained using membranes fabricated from readily available natural resources like clays and waste materials, namely low-cost ceramic membranes. Such membranes also require lower sintering temperatures for fabrication than commercially available ones (Hubadillah et al. 2018).

The current study aims to produce a novel, cost-effective, eco-friendly ceramic membrane using Fuller's earth clay (FEC) and rice husk ash (RHA) as primary raw materials and test its potential in the treatment of dairy and oil industry wastewater. The impact of sintering temperature on membrane characteristics such as shrinkage, porosity, chemical resistance, and mechanical strength are studied at varying sintering temperatures. The effectiveness of the membrane was investigated by testing its ability to microfilter food industry wastewater in terms of permeate flux, removal of COD, TSS, pH, and conductivity while varying specific operational parameters, such as the pressure applied and the cross-flow rate.

Locally available low-cost FEC was procured from Central & Western India Chemicals, India. RHA was obtained from the local fly ash bricks industry, Tadepalligudem, Andhra Pradesh, India. FEC, a bentonite-based clay, has elevated plasticity, lubricity, and a substantial surface area. These inherent benefits negate the necessity for organic additives to enhance plasticity. RHA, consisting of silica and carbon, serves as an additive for ceramic membranes. In this study, the collected RHA was ball-milled and sieved through 75 μm mesh to maintain the consistency. The material that passes through the 75 μm size mesh was utilized for the membrane fabrication. This route is reliable and similar to the other research work, in which the RHA was ball milled and sieved to get a uniform-size powder. Silica enhances thermal and mechanical stability, while the carbon content contributes to porosity, collectively enhancing membrane performance. Given these remarkable attributes of both the raw materials, hold significant promise for cost-effective applications in ceramic membrane production. Such ceramic membranes provide exceptional chemical and mechanical stability. As a result, they can endure rigorous chemical treatments used for cleaning processes. This capability enhances both their reproducibility and shelf life, unlike polymeric membranes. Sodium hydroxide and hydrochloric acid were sourced from Nice Chemicals (P) Ltd, Kochi, India. A double distillation unit made of glass, supplied by Accumax, New Delhi, India, was utilized to purify the water during the experiments.

Raw materials were characterized using techniques including XRF, XRD, and TG-differential thermal analysis (DTA). The shrinkage values of the fabricated tubular membranes, their porosity using Archimedes' principle, and corrosion resistance were calculated as reported elsewhere (Satyannarayana et al. 2022). The FTIR and SEM analyses were performed to examine the functional groups in the membrane and its surface morphology, respectively.

Membrane fabrication was carried out using locally available FEC and RHA in an appropriate ratio by extrusion method. In the extrusion process, a uniform extrudable paste, having undergone an ageing period, is propelled through a nozzle using a piston extruder. This extruder variant comprises a piston, a tube, and an easily manageable die. The piston ensures the application of precise pressure on the paste, facilitating its continuous passage through a die with a smaller cross-sectional area. The characteristics – shape, dimensions, porosity, and pore size distribution of the final product are determined by the specific die employed. In ceramic membrane production, the extrusion method is utilized to create porous tubular membranes, imparting robustness to the resultant green membranes. No binders were used for the preparation of paste for plasticity. This paste was then kept for ageing overnight in a closed container to reach homogeneity and improve the quality of the paste by removing air bubbles. After extrusion, membranes were allowed for natural drying, sintered at 850 °C for 6 h, trimmed to approximately 75 mm length, and polished using silicon carbide abrasive paper. After washing and sonicating the membranes, they were dried and used for further characterization. The fabricated membranes underwent various characterization tests to assess their shrinkage, porosity, mechanical strength, corrosion resistance, hydraulic permeability, pore size measurements, and SEM analysis.

The following equation was used to compute the shrinkage values of the fabricated tubular membrane.
formula
(1)

Vg and Vs are the volumes of membrane before and after sintering, respectively.

Archimedes' principle was employed for measuring the porosity of the fabricated membrane. After soaking the membranes in distilled water for 24 h, any remaining water present on the surface of the membrane was gently removed, and the wet weight (Wwet) was noted. Subsequently, the membranes were kept in HAO at 100 °C for 3 h and their dry weight (Wdry) was noted. The porosity (%) was calculated using the formula provided in Equation (2), with density of (ρw), and volume of membrane (Vm) taken into account.
formula
(2)
The membranes' ability to withstand corrosion was tested in both acidic and basic conditions, by measuring the percentage of weight loss. Initially, the sintered membranes were subjected to an immersion test in a solution containing 1M NaOH and 0.1M HCl to assess their resistance to corrosion. The sintered membranes were weighed both before (⁠⁠) and after (⁠⁠) being immersed in 100 mL of acid or alkali solutions for a week. Subsequently, the weight loss percentage of the membrane was computed by applying the following equation:
formula
(3)
A well-known three-point bending technique was employed to assess the mechanical strength of the fabricated membrane using a Universal Testing Machine. Subsequently, a vertical load was applied to the membrane at a rate of 1 until cracks were detected. The mechanical strength was finally determined by making use of the subsequent equation:
formula
(4)

Here, F represents the force perpendicular to the membrane (N), L is the distance between the two sample beams (mm), and denote the outer and inner diameters of the sample (mm).

A locally fabricated cross-flow set-up was utilized in the current study to conduct microfiltration experiments and determine the pure water flux, permeability, and hydraulic pore size. Equation (5) was utilized to compute the pure water flux for various time periods and pressures as shown in the following equation:
formula
(5)
where Vp represents permeate's volume through the membrane (L), Am denotes membrane's area (m2), and t denotes the duration for collecting permeate (h).
Further, permeability calculation was done using the following equation (Darcy's law),
formula
(6)

Here, Lp represents membrane's permeability (L/m2 h), and denotes applied pressure (bar).

Later, the membrane's hydraulic pore size was computed by making use of the following equation (Hagen–Poiseuille equation) (Gitis & Rothenberg 2016),
formula
(7)
where represents membrane's porosity, r denotes pore radius, represents water viscosity, denotes tortuosity factor which is 1 for cylindrical pore, and l is the pore length where the membrane thickness is generally considered, i.e., 2.5 mm.
The combination of Equations (6) and (7) led to the determination of pore radius, as shown by the following equation (Vasanth et al. 2013; Almandoz et al. 2015; Kumar et al. 2015; Das et al. 2016; Gitis & Rothenberg 2016; Rani & Kumar 2021; Satyannarayana et al. 2022)
formula
(8)

SEM analysis was performed to examine the membrane's morphology. Measurements were carried out using VEGA 3, SBH, TESCAN Brno S.R.O, Czech, Republic instrument.

For the present study, dairy wastewater was obtained from Sri Chakra Milk Products (Tadepalligudem, Andhra Pradesh, India) following primary treatment. In a similar manner, wastewater from palm oil processing was obtained from 3F Industries Ltd (Tadepalligudem, Andhra Pradesh, India). These collected samples were refrigerated at temperatures below 4 °C until they were used for subsequent experiments.

A cross-flow microfiltration set-up was locally fabricated to conduct microfiltration experiments. A visual representation of the experimental set-up employed to measure water flux is provided in Figure 1. Different applied pressures varying from 1.03 to 2.41 bar and cross-flow rates ranging from 30 to 150 Lph were employed during the experiments. The study analyzed the efficiency of the process by examining the percentage removal (R%) of COD and TSS removed from the feed to permeate, which was calculated using the following equation (Mulder 1996; Kumar et al. 2015; Mouiya et al. 2019)
formula
(9)
where Cf is the concentration in the feed stream, Cp is the concentration in the permeate stream, and R is the removal (%). Here, C indicates the properties of wastewater, such as COD, TSS, etc.
Figure 1
Cross-flow microfiltration set-up.
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Cross-flow microfiltration set-up.

Figure 1
Cross-flow microfiltration set-up.
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Cross-flow microfiltration set-up.

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The membrane cleaning and regeneration procedure was carried out after each experimental run. This was followed by washing using a cleansing agent, a commercially obtained surf-excel powder solution of 1 g/L, for an hour for eliminating any adsorbed proteins within the pores or deposited oil on the membrane's surface. Subsequently, the entire system underwent cleaning by passing double-distilled water for an hour. Next, the membrane's water flux was assessed for ensuring that there was an insignificant decrement in flux because of the partial pore obstruction. To confirm the complete restoration of the membrane, hydraulic permeability was computed and juxtaposed with that of the fresh membrane. The difference in permeability values between fresh and cleaned membranes was ensured to be less than ± 2%. The membrane was then used for further experiments (Kumar et al. 2016a).

The quantitative identification of metal oxides present in raw materials is achieved through the use of the XRF technique. Typically, clays comprise aluminosilicates, water, and impurities, including iron. The chemical composition of FEC and RHA is detailed in Table 1 (Subbareddy et al. 2020; Rani & Kumar 2022). XRF analysis revealed that RHA mainly consists of SiO2 (92.17 wt.%). This strongly agreed with the other research study (Satyannarayana et al. 2022).

Table 1

The chemical composition of FEC and RHA analyzed by XRF

OxidesSiO2Al2O3Fe2O3K2OTiO2CaOSO3Others
FEC wt.% 63.33 19.17 10.96 3.14 1.44 1.12 0.51 0.33 
RHA wt.% 92.171 0.356 0.272 1.298 – 0.897 0.378 4.628 
OxidesSiO2Al2O3Fe2O3K2OTiO2CaOSO3Others
FEC wt.% 63.33 19.17 10.96 3.14 1.44 1.12 0.51 0.33 
RHA wt.% 92.171 0.356 0.272 1.298 – 0.897 0.378 4.628 
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In Figure 2, the XRD analysis reveals that before sintering, FEC predominantly consists of montmorillonite; the sharp peaks can identify approximately 8.41°, 19.81°, 24.85°, and 34.85°, as well as palygorskite with a distinctive peak at 12.32°, and quartz with peaks at 20.82° and 26.60°, as reported by Kulkarni et al. (2021) and Rani & Kumar (2022).
Figure 2
XRD pattern of raw materials.
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XRD pattern of raw materials.

Figure 2
XRD pattern of raw materials.
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XRD pattern of raw materials.

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The FTIR analysis was done to identify the probable functional groups present in raw materials. Within the spectra (Figure 3), the presence of absorption zones at approximately 3,616 and 3,694 depicts stretching vibrations of OH groups found in montmorillonite and palygorskite. However, these absorption bands tend to disappear after the sintering process. Peaks around 1,637 ⁠, due to H–O–H stretching and bending of surface physisorbed water, were no longer present after the sintering process (Rani & Kumar 2022). The stretching of tetrahedral Si–O–Si is responsible for the peak observed at 977 while the peak at 797 represents the Si–O bond, providing evidence for the existence of quartz, a finding that was also confirmed by XRD and XRF analyses (Subbareddy et al. 2020).
Figure 3
FTIR spectrum of membranes.
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FTIR spectrum of membranes.

Figure 3
FTIR spectrum of membranes.
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FTIR spectrum of membranes.

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The TGA profile of the raw material mixture shows a gradual release of water molecules adsorbed on the particle's surface up to 150 °C, responsible for the 10% weight loss detected (Figure 4). The presence of RHA and the dehydroxylation reaction leads to the elimination of the surface hydroxyl group between the temperatures of 350 and 600 °C, which are responsible for the remaining weight loss. The raw material showed a total mass loss of approximately 20% within the temperature range of operation. This is consistent with the DTA analysis (Figure 5) (Rani & Kumar 2022). Beyond 750 °C, no significant weight loss is observed, indicating that a sintering temperature above 750 °C is necessary to obtain a mechanically and thermally strong membrane (Kumar et al. 2016b). On analyzing DTA, an endothermic peak was observed between 70 and 90 °C, representing the loss of adsorbed water molecules, and an exothermic peak around 500 °C, indicating the combustion of volatile materials and carbon can be noticed. However, minimal weight loss is seen above 750 °C. Based on TG-derivative thermogravimetry (DTG) and DTA of FEC and RHA, the sintering temperature is established beyond 750 °C (Satyannarayana et al. 2022).
Figure 4
TG-DTA of FEC.
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TG-DTA of FEC.

Figure 5
TG-DTA of RHA.
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TG-DTA of RHA.

The overall measurable properties of the fabricated membrane, including shrinkage percentage, porosity percentage, mechanical strength, and weight loss percentage in acidic and basic media, are presented in Table 2. The cost of the membrane was estimated to be $73.44/m2 at laboratory-level production (Satyannarayana et al. 2022). The measured characteristics of dairy and palm oil industry wastewater are presented in Table 3.

Table 2

Membrane properties

Property of the membraneValue
Porosity 61% 
Hydraulic pore size 0.115 μm 
Flexural strength 10 MPa 
Shrinkage 14.8% 
Permeability 43.29 L/m2 h bar 
Weight loss (HCl) <1% 
Weight loss (NaOH) <2% 
Property of the membraneValue
Porosity 61% 
Hydraulic pore size 0.115 μm 
Flexural strength 10 MPa 
Shrinkage 14.8% 
Permeability 43.29 L/m2 h bar 
Weight loss (HCl) <1% 
Weight loss (NaOH) <2% 
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Table 3

Characteristics of wastewaters

PropertyDairy industry wastewaterPalm oil industry wastewater
pH 8.62 ± 0.02 2.05 ± 0.02 
Conductivity (mS) 2.2 ± 0.1 14.3 ± 0.1 
Total solids (mg/L) 1,889 ± 4 10,415 ± 5 
TSS (mg/L) 265 ± 3 518 ± 4 
TDS (mg/L) 934 ± 3 9,889 ± 4 
COD (mg/L) 1,999 ± 10 1,596 ± 9 
PropertyDairy industry wastewaterPalm oil industry wastewater
pH 8.62 ± 0.02 2.05 ± 0.02 
Conductivity (mS) 2.2 ± 0.1 14.3 ± 0.1 
Total solids (mg/L) 1,889 ± 4 10,415 ± 5 
TSS (mg/L) 265 ± 3 518 ± 4 
TDS (mg/L) 934 ± 3 9,889 ± 4 
COD (mg/L) 1,999 ± 10 1,596 ± 9 
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Furthermore, SEM analysis was carried out to examine the membrane's surface morphology, as depicted in Figure 6(a) and 6(b). These images offer insights into the uniformity of the membrane surface (Achiou et al. 2017). The surface is consistent and highly porous, with no pinholes, cracks, or noticeable imperfections. Additionally, the membrane has a remarkably smooth and flawless surface (Kumar et al. 2016b).
Figure 6
SEM images of the sintered membrane (a) inner and (b) outer.
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SEM images of the sintered membrane (a) inner and (b) outer.

Figure 6
SEM images of the sintered membrane (a) inner and (b) outer.
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SEM images of the sintered membrane (a) inner and (b) outer.

Close modal
In Figure 7, a constant water flux pattern was observed across different time intervals and pressures. Figure 8 displays a linear relationship between the rise in water flux and the applied pressure, confirming adherence to Darcy's law. According to Darcy's law, the flow rate is directly proportional to the pressure gradient. Therefore, as the applied pressure increases, the flow rate should also increase proportionally. This linear correlation validates the applicability of Darcy's law in describing the flow behavior of the observed system. The membrane's permeability (Lp) was computed from the graph's slope and determined to be 43.29 L/m2 h bar, and the average pore size of the membrane was computed as 0.115 μm (Vasanth et al. 2013).
Figure 7
Water flux function on time.
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Water flux function on time.

Figure 7
Water flux function on time.
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Water flux function on time.

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Figure 8
Water flux function on pressure.
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Water flux function on pressure.

Figure 8
Water flux function on pressure.
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Water flux function on pressure.

Close modal
The same experimental set-up (Figure 1) was employed to conduct microfiltration studies using food industry effluents for 1 h at various applied pressures (1.03–2.41 bar) at a cross-flow rate of 150 Lph. Figure 9(a) and 9(b) illustrates permeate fluxes over time for dairy and palm oil industry wastewater. It is observed that a rise in applied pressure caused a corresponding increase in permeate flux. But eventually, both types of wastewaters experienced a decline in permeate flux and later became gradual due to fouling. Moreover, the initial decrease in flux was more pronounced at higher pressures because of the rapid creation of a cake layer on the membrane's surface (Achiou et al. 2017). Furthermore, higher permeate flux was noticed for palm oil industry wastewater compared to dairy industry wastewater at all pressures, which is attributed to high organic matter and COD in dairy industry wastewater. The time-dependent removal of COD at various applied pressures is presented in Figure 9(c). The results indicate that the maximum COD removal percentages achieved were 93.3 and 90% for the dairy and palm oil industries at 1.03 bar pressure (Kumar et al. 2016a). Both wastewaters achieved a turbidity removal percentage of 99% at 1.03 bar pressure, successfully eliminating the suspended and colloidal particles. pH and conductivity values underwent negligible changes as the membrane does not hinder conductivity due to its pore size being large enough to retain soluble salts (Achiou et al. 2017).
Figure 9
Varying permeate flux with time for (a) dairy and (b) palm oil industry wastewater, and (c) removal (%) of COD and TSS of the dairy and palm oil industry wastewater at various applied pressures under a steady flow rate.
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Varying permeate flux with time for (a) dairy and (b) palm oil industry wastewater, and (c) removal (%) of COD and TSS of the dairy and palm oil industry wastewater at various applied pressures under a steady flow rate.

Figure 9
Varying permeate flux with time for (a) dairy and (b) palm oil industry wastewater, and (c) removal (%) of COD and TSS of the dairy and palm oil industry wastewater at various applied pressures under a steady flow rate.
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Varying permeate flux with time for (a) dairy and (b) palm oil industry wastewater, and (c) removal (%) of COD and TSS of the dairy and palm oil industry wastewater at various applied pressures under a steady flow rate.

Close modal
In Figure 10, permeate flux over time is plotted for various cross-flow rates (30–150 Lph) at an applied pressure of 1.03 bar. On increasing the cross-flow rate, permeate flux increases because of reduced concentration polarization and decreased fouling layer thickness on the membrane's surface because of the shear stress-induced. However, the flux rate reduces, further increasing the cross-flow rates, likely due to a restriction in cake layer creation on the membrane's surface (Kumar et al. 2016a). A maximum COD removal of 92 and 89% for the dairy and palm oil industries, respectively, are observed at 30 Lph. Both wastewaters achieved a turbidity removal percentage of 98% at 30 Lph.
Figure 10
Varying permeate flux with time for (a) dairy and (b) palm oil industry wastewater at a constant pressure.
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Varying permeate flux with time for (a) dairy and (b) palm oil industry wastewater at a constant pressure.

Figure 10
Varying permeate flux with time for (a) dairy and (b) palm oil industry wastewater at a constant pressure.
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Varying permeate flux with time for (a) dairy and (b) palm oil industry wastewater at a constant pressure.

Close modal
For fouling analysis, four fouling models were introduced to explain the relevant decline in microfiltration flux data by Hermia: cake filtration (CF), intermediate (IPB), standard (SPB), and complete pore blocking (CPB) models (Emani et al. 2014). In standard pore blocking, solute particles can become trapped along the pore pathway, leading to a progressive reduction in permeate volume as filtration time progresses. CPB occurs when the solute particle size significantly exceeds the diameter of the membrane's pores. In this case, the inner portion of the pore might remain unobstructed while blockage occurs on the membrane's surface. Intermediate pore blocking arises when the size of the solute particles closely matches that of the membrane's pores. During filtration, these solute particles accumulate and settle atop one another, gradually diminishing the available surface area over time. In CF, the solute particles are notably larger than the membrane pores. As the filtration process unfolds, these solute particles settle onto the membrane surface, forming a layer akin to a cake. This layer becomes progressively thicker over time, introducing resistance to the flow of permeate. However, this layer can be eliminated using mechanical methods, allowing the membrane to be further utilized (Kumar et al. 2016b). The following equations represent the four fouling models:
formula
(10)
formula
(11)
formula
(12)
formula
(13)

Here, J represents the permeate flux, and t stands for the filtration time. ⁠, ⁠, ⁠, and are slopes, as well as ⁠, ⁠, ⁠, and are intercepts in Equations (10)–(13). Linearized plots of the above equations are used to find the fitness of data in a particular model.

To determine the best fit, the value of the graphs plotted based on respective model equations using flux data. It can be observed from permeate flux graphs (Figure 11) that the decline in flux is higher in the initial period. As a result, the models' fitness was evaluated in two stages: case I (first 30 min) and case II (31–60 min), and the values. Upon analysis, it can be observed that the flux decline conforms to the CF model in both cases I and II, with an values ranging from 0.762 to 0.981. Further demonstrates that CF remains the prevailing mechanism throughout the entire 60 min operation. Nevertheless, the CF model exhibited the least deviation, indicating its closest alignment with the experimental data. Based on the aforementioned observations, it can be inferred that CF is the most suitable mechanism for the fabricated ceramic membrane in both wastewater treatments (Kumar et al. 2016b).
Figure 11
Linearized graphs of different fouling models (a–d) for the treatment of the dairy and palm oil industry wastewater.
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Linearized graphs of different fouling models (a–d) for the treatment of the dairy and palm oil industry wastewater.

Figure 11
Linearized graphs of different fouling models (a–d) for the treatment of the dairy and palm oil industry wastewater.
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Linearized graphs of different fouling models (a–d) for the treatment of the dairy and palm oil industry wastewater.

Close modal

The current study effectively created a cost-effective tubular microfiltration ceramic membrane through the extrusion method, utilizing inexpensive FEC as a primary material. The performance of the membrane was determined by effectively employing it to treat wastewater produced by both the dairy and oil industries, with a maximum COD removal rate of 93.3 and 90%, respectively, at 0.35 bar. Moreover, the membrane exhibited a remarkable ability to remove 99% of TSS from both types of wastewaters. The CF was identified as the most suitable model based on fouling analysis using four of Hermia's models, indicating that the manufactured membrane has better membrane regeneration ability compared to the other three models and is less prone to fouling. These findings demonstrate the potential applicability of the newly developed low-cost tubular ceramic membrane for treating wastewater from food industries.

This work was financially supported by the Science and Engineering Research Board, Department of Science and Technology, Government of India (File No: EEQ/2018/001432). The authors acknowledge Mr K.V.V. Satyannarayana, Ms S. Lakshmi Sandhya Rani and Ms R. Padmashree for providing the necessary support to carry out the work.

All relevant data are included in the paper or its Supplementary Information.

The authors declare there is no conflict.

Achiou
B.
,
Elomari
H.
,
Bouazizi
A.
,
Karim
A.
,
Ouammou
M.
,
Albizane
A.
,
Bennazha
J.
,
Alami Younssi
S.
 &
El Amrani
I. E.
2017
Manufacturing of tubular ceramic microfiltration membrane based on natural Pozzolan for pretreatment of seawater desalination
.
Desalination
419
,
181
–
187
.
Google Scholar
Crossref
Search ADS
 
AitAli
S.
,
Ziani
S.
,
Yahiaoui
I.
,
Brahmi
A.
,
Boudrahem
F.
 &
Aissani-Benissad
F.
n.d.
Application of central composite design and response surface methodology for the study of extraction of gentian violet dye in aqueous solution by polystyrene membrane modified with oleic acid
.
Environmental Progress & Sustainable Energy
42
(6),
e14200
.
Google Scholar
Crossref
Search ADS
 
Almandoz
M. C.
,
Pagliero
C. L.
,
Ochoa
N. A.
 &
Marchese
J.
2015
Composite ceramic membranes from natural aluminosilicates for microfiltration applications
.
Ceramics International
41
,
5621
–
5633
.
Google Scholar
Crossref
Search ADS
 
Belaid
T.
,
Aitali
S.
,
Benamor
M.
 &
Belhamel
K.
2009
Synthesis and characterization of new chelating resin functionalized with pyrocatechol violet and its application as extractant for zinc (II)
. In:
Materials Science Forum
(Gabouze, N., ed.). Vol.
609
, pp.
75
–
80
.
Trans Tech Publishing, Stafa-Zurich, Switzerland
.
Google Scholar
Crossref
Search ADS
 
Croft
C. F.
,
Inês
M.
,
Almeida
G. S.
 &
Kolev
S. D.
2023
Characterisation of micro polymer inclusion beads by thermogravimetric analysis
.
Polymer
283
,
126203
.
Google Scholar
Crossref
Search ADS
 
Das
B.
,
Chakrabarty
B.
 &
Barkakati
P.
2016
Preparation and characterization of novel ceramic membranes for micro-filtration applications
.
Ceramics International
42
,
14326
–
14333
.
Google Scholar
Crossref
Search ADS
 
Gitis
V.
 &
Rothenberg
G.
2016
Ceramic Membranes – New Opportunities and Practical Applications
, 1st edn.
Wiley-VCH Verlag
,
Weinheim
,
Germany
.
Google Scholar
Crossref
Search ADS
 
Hubadillah
S. K.
,
Othman
M. H. D.
,
Ismail
A. F.
,
Rahman
M. A.
,
Jaafar
J.
,
Iwamoto
Y.
,
Honda
S.
,
Dzahir
M. I. H. M.
 &
Yusop
M. Z. M.
2018
Fabrication of low cost, green silica based ceramic hollow fibre membrane prepared from waste rice husk for water filtration application
.
Ceramics International
44
(
9
),
10498
–
10509
.
Google Scholar
Crossref
Search ADS
 
Kulkarni
P.
,
Watwe
V.
,
Chavan
T.
 &
Kulkarni
S.
2021
Artificial neural networking for remediation of methylene blue dye using Fuller's earth clay
.
Current Research in Green and Sustainable Chemistry
4
,
100131
.
https://doi.org/10.1016/j.crgsc.2021.100131
.
Google Scholar
Crossref
Search ADS
 
Kumar
R. V.
,
Goswami
L.
,
Pakshirajan
K.
 &
Pugazhenthi
G.
2016a
Dairy wastewater treatment using a novel low cost tubular ceramic membrane and membrane fouling mechanism using pore blocking models
.
Journal of Water Process Engineering
13
,
168
–
175
.
Google Scholar
Crossref
Search ADS
 
Kumar
R. V.
,
Monash
P.
 &
Pugazhenthi
G.
2016b
Treatment of oil-in-water emulsion using tubular ceramic membrane acquired from locally available low-cost inorganic precursors
.
Desalination and Water Treatment
57
(
58
),
28056
–
28070
.
https://doi.org/10.1080/19443994.2016.1179221
.
Google Scholar
Crossref
Search ADS
 
Mouiya
M.
,
Bouazizi
A.
,
Abourriche
A.
,
Benhammou
A.
,
Hafiane
Y. E.
,
Ouammou
M.
,
Abouliatim
Y.
,
Younssi
S. A.
,
Smith
A.
 &
Hannache
H.
2019
Fabrication and characterization of a ceramic membrane from clay and banana peel powder: Application to industrial wastewater treatment
.
Materials Chemistry and Physics
227
,
291
–
301
.
Google Scholar
Crossref
Search ADS
 
Mulder
M.
1996
Basic Principles of Membrane Technology
, 2nd edn.
Kluwer Academic Publishers
,
Dordrecht, Netherlands
.
Google Scholar
Crossref
Search ADS
 
Rani
S. L. S.
 &
Kumar
R. V.
2021
Insights on applications of low-cost ceramic membranes in wastewater treatment: A mini-review
.
Case Studies in Chemical and Environmental Engineering
4
.
https://doi.org/10.1016/j.cscee.2021.100149
.
Google Scholar
 
Satyannarayana
K. V. V.
,
Rani
S. L. S.
,
Baranidharan
S.
 &
Kumar
R. V.
2022
Indigenous bentonite based tubular ceramic microfiltration membrane: Elaboration, characterization, and evaluation of environmental impacts using life cycle techniques
.
Ceramics International
48
(
19, Part B
),
28843
–
28855
.
https://doi.org/10.1016/j.ceramint.2022.03.156
.
Google Scholar
Crossref
Search ADS
 
Subbareddy
Y.
,
Kumar
R. N.
,
Sudhakar
B. K.
,
Rayappa Reddy
K.
,
Martha
S. K.
 &
Kaviyarasu
K.
2020
A facile approach of adsorption of acid blue 9 on aluminium silicate-coated Fuller's Earth – equilibrium and kinetics studies
.
Surfaces and Interfaces
19
,
100503
.
Google Scholar
Crossref
Search ADS
 
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