Introduction

Water is a crucial resource for all life on earth, including humans and animals. Most of the planet’s water is contained in oceans, lakes, and rivers, which make up over 70% of the earth’s surface. Surface freshwater is only 1% of all water on the planet, with only a small fraction of this available for human use. Underground reserves of freshwater represent about 2% of global water resources, with ice-cored glaciers being the largest source (Lee et al. 2010). Recycling of water using purification techniques is extremely essential with such a limited supply of water. In addition, existing water quality standards are insufficient to reflect the health risks posed by many water contaminants, which if consumed can cause various diseases, such as cholera, dysentery, and typhoid fever (Lee et al. 2010).

Jepsen et al. (2018), reviewed fouling detection, removal of particles, prevention of fouling, dynamic and static modeling of particulate matter initiating fouling on filtration membranes. This research emphasized the manipulation of the membrane process from a process control perspective for water treatment on offshore oil rigs. Da̧browski et al. (2005), comprehensively reviewed the irreversible adsorption of phenols on activated carbon filter membranes. Since activated carbon filters are an evolving technique. Foo et al. (2009), reviewed the electrosorption process on activated carbon filter membranes to minimize maintenance costs. Similarly extending on this evolving research on activated carbon filter membranes Ioannidou et al. (2007), reviewed all techniques to derive such membranes from organic agriculutural by-products. Bellona et al. (2004), studied the reasons for the incomplete removal of pesticides, disinfected by-products, endocrine disrupting compounds, and pharmaceutically active compounds in reverse osmosis (RO) techniques of water purifcation for domestic consumption.

Reviews have been published for specific membrane-based filtration techniques or specific processes affecting them for a specific application. The existing literature on filtration systems tends to focus on individual types of filtration systems, such as RO or activated carbon filtration. A holistic review of all membrane-based filtration techniques with an overall practicality is a gap in the available literature. Additionally, a focus on the outlook of these techniques with recent advancements is also not available. Therefore, a comprehensive review spanning the work done in the last thirty years, that provides an in-depth analysis of the various types of membrane-based filtration techniques, along with their practicality and outlook would be the objective of this article. This comparative analysis of the different types of filtration techniques will provide designers and researchers in various application fields with a platform to understand the technicalities, advantages and limitations of each technique. Moreover, an outlook based on a critical analysis of existing research would provide potential research directions for the scientific community which will contribute to the development of more effective and sustainable filtration technologies.

Overview of water filtration techniques

Water filtration systems are critical in ensuring that water is safe for human consumption by removing impurities from groundwater and seawater. A broad overview of the different water filtration techniques, with the highlighted column discussed in this paper, is in \* MERGEFORMAT Fig. 1.

Fig. 1
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Broad categorization of water filtration techniques with emphasis on highlighted subcategory

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A rigorous water purification flow chain involves a combination of the aforementioned techniques. Usually, chemical techniques are used to disinfect sewage water before it is passed through membranes and finally distilled for human consumption. The scope of this paper is limited to the broad categories of membrane-based water filtration techniques, including reverse osmosis (RO), microfiltration (MF), ultrafiltration (UF), and activated carbon filtration (ACF) in which the first three are pressure driven as shown in Fig. 2.

Fig. 2
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Schematic of pressure-driven membrane water treatment system

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There are eight stages involved in the treatment of water (Hirunpraditkoon et al. 2015): (1) Catchment involves diverting and storing water. (2) Adduction—the movement of water from its source to the point where it is treated for consumptin. (3) Coagulation: During the coagulation phase, impurities are removed from a solution by passing it through an active carbon membrane. (4) Flocculation: The process involves mechanically agitating the water to remove impurities in large pieces (Hirunpraditkoon et al. 2015). (5) Decantation: The process of decanting separates liquid from sediment by using gravity. (6) Filtration: The water is then filtered through layers of coarse sand and fine gravel before being poured over activated carbon; (7) Disinfection: After this, it’s doused with chlorine or fluorine to kill any remaining bacteria. (8) Reservation: Reservoirs hold the water that is supplied to homes and businesses.

Membrane based water filtration techniques

Reverse osmosis (RO)

RO is a technique that uses pressure to remove dissolved solids from a solution. It is a popular filtration system that deploys a semi-permeable membrane to eliminate impurities from water. The system is particularly useful for removing organics from water, as it can be used to remove both organic matter and ions. This process creates a fresh, pure stream of water that can be used for drinking or irrigation purposes. These membranes let large water molecules through while rejecting smaller salt ions.

Conventional wastewater treatment processes do not remove dissolved solids that must be treated with the RO process. The use of RO to treat effluents from various industrial processes (Bódalo-Santoyo et al. 2003), including those generated by the petrochemical and chemical industries as well as food processing plants has been reported in the literature (Bódalo-Santoyo et al. 2003). In more recent years, studies have shown that individual contaminants in water can be harmful to living organisms; thus, relatively few researchers focus on removing these specific pollutants from aqueous solutions using this method. Nevertheless, a research was examined that described how to purify wastewater from such distilleries when UF and RO membranes are used (Bódalo-Santoyo et al. 2004). For the removal of plastic additives and pesticides, as well as pharmaceutically active compounds that are dissolved in water several studies have been looked up on the application of RO systems (Schutte 2003).

RO semi-permeable membranes are most commonly made from polyamide materials or natural and synthetic cellulose acetate materials (Hailemariam et al. 2020). Cellulose ester is a synthetic material that has been used for many years in industrial applications (Moresi et al. 2002). It is made from cellulose, which is a natural polymer found in plants. Polyamide is a synthetic material that is made from nylon (Moresi et al. 2002). It was first developed in Germany in 1968 for use as a membrane in RO systems (Moresi et al. 2002). These materials can be combined with other chemicals to create different types of RO membrane products including barrier membranes and nanofiltration membranes (Lee et al. 2010). Barrier membranes have pores that are larger than nanofiltration membranes’ pores, but both types of membranes have pores smaller than those used in conventional dialysis treatment processes including UF. These membranes have a high surface area and allow large amounts of small molecules to pass through them (Moresi et al. 2002). Cellulose acetate and polyamide membranes block the passage of inorganic salts like NaCl with lower rejection rates for organic compounds (Schutte 2003). The rejection of organics varies widely, ranging from 0.3–0.96 (Schutte 2003). Additionally, an RO system can be used for several purposes including the separation of gas from liquids (Zhang et al. 2021).

Ultrafiltration (UF)

In 1861, the first laboratory experiment regarding UF was performed with natural bovine pericardium (Jinhua 2021). UF was first proposed by Becchold in the early twentieth century (Drewes et al. 2003), but the idea remained dormant until it reemerged in the early 1960s (Jinhua 2021). With various new materials on offer, UF membranes quickly became a commercial reality during the 1970s (Qi et al. 2011). By this time Cellulose Acetate membranes had been developed followed by the successful development of polysulfone hollow fiber membranes in 1980 (Bhattacharya et al. 2013). UF, originally developed for the use in the chemical as well as pharmaceutical industries, saw more widespread application from the 1990s, due to continuous development of charged membranes (Qi et al. 2011). Recently, China developed PS, PAN, and PSA UF membranes—among others (Yan et al. 2009) —which are used for domestic water treatment.

UF is a means for separating, concentrating, and purifying solutions between micro- and nanofiltration via its membrane separation technology—and it can be used for applications as diverse as drinking water treatment or biopharmaceutical processing (Drewes et al. 2003). It is a pressure-driven membrane separation process that utilizes a semi-permeable membrane to separate solvents and solutes based on their molecular size. UF membranes separate particles from wastewater, producing clear and clean water for reuse or discharge into surface waters. Such water distillers reduce the presence of microorganisms in drinking water, improving its safety by eliminating viruses, colloidal substances, and suspended particles (Al Aani et al. 2020).

The difference in pressure acts as the driving force between the sides of the membrane in the UF process. Considering a UF membrane as a medium for filtration, static pressure causes solvent and solute particles with low molecular weight and smaller pore diameters to pass through the high-pressure side (raw material liquid) to low-pressure side (UF), by contrast, solute particles are trapped on the high-pressure side due to their high molecular weight (Ng and Imperial College Press 2006). However, in some cases, solvents do not match the size of the molecules to be filtered. In this case, even though solvent should flow through a membrane it will not necessarily remove all targeted compounds. The chemical characteristics of the membrane surface may make it more or less vulnerable to electrostatic effects (Basri et al. 2011). UF membranes employ a three-step process through which particles become retained on the membrane: adsorption onto the surface and into pores when in contact with them, insertion through mechanical pores resulting in its retention within them, and removal by increasing size exclusion via fouling when particles approach micrometric dimensions (Basri et al. 2011). After being coagulated, the water passes through the sedimentation process to be directly passed through a UF membrane for purification (Yang and Chen 2013).

Its operating pressure range is 0.1–0.8MPa, and it separates particles with diameters of about 0.005–10 μm depending on the size spectrum from 500Da up through 500,000 Da (Ng and Imperial College Press 2006).

The pore size of UF membranes typically ranges from 1 to 100 nm, allowing smaller molecules like water, salts, and organics to pass through while rejecting larger molecules and suspended solids (Yan et al. 2009). The UF process has an effluent turbidity of < 0.1 NTU and a particulate matter removal rate of up to 99.9% (Sabzali 2016). Studies have shown that these membranes can remove up to 7 logs (99.9999%) in total coliform bacteria, up to 4.4–7 logs for Cryptosporidium parvum and Giardia lamblia cysts—and even 6 logs or more for some viruses like the MS2 bacteriophage (Toyomoto and Higuchi 1992; Skelton 2000).

Common materials used for UF membranes include polymers like polysulfone, polyethersulfone, and polyvinylidene fluoride. These polymeric membranes provide good mechanical strength, chemical resistance, and thermal stability while allowing for precise control over pore size. The membrane material is configured into different module designs like hollow fiber, spiral wound, plate and frame, or tubular. Hollow fiber modules containing thousands of small diameter membrane fibers are commonly used to maximize surface area (Zhang et al. 2021). The membrane material, pore size, and module design are optimized for the specific application and properties of the feed solution to achieve efficient separation and flux while minimizing fouling.

UF is one of the most widespread utilizations of membrane technology for treating water with impurities. In comparison to conventional systems, the UF process has higher turbidity rates and greater filtration accuracy with its water quality being more reliable and stable. The UF membrane filter is effective in removing pathogens, viruses, and micro-organisms, such as bacteria, Giardia, Cryptosporidium and chemical pollutants (Sabzali 2016; Toyomoto and Higuchi 1992). UF produces water that does not need to be reinfected and so does not require the addition of other chemical agents. This simplifies the process flow, making it possible for plant operators to control their plants using automated systems (Ismail and Matsuura 2016). Moreover, it is significantly more efficient than the conventional and advanced treatment process, conserving as much as five times less water and energy (Ismail and Matsuura 2016).

An application of the UF process at large scale can be seen by its use in the treatment of Yangtze River water, beginning with a pretreatment stage and ending with UF. At a flow rate of 16.83—17.67 L/min, the effluent’s 15-16 L/min flushes waste away quickly (Colwell 1998). This unit treats a flow equivalent to 89–93% of the incoming water, providing better water quality and covering an area of about 1.28 m2—a considerable saving in space as compared to the conventional processes (Colwell 1998). Furthermore, an experiment was conducted to find the cost of water production via UF on a domestic scale. It was 0.23 yuan per cubic meter, and electricity consumption was about 18 kilowatt hours per cubic meter (Laîné et al. 2000). The addition of ozone and the use of activated carbon advanced treatment technology to conventional water treatment will increase production costs by 0.3 yuan/m3 (Laîné et al. 2000). These studies indicate that the overall cost of using the UF processes comes out to be lower than that of conventional processes (Cuartucci 2020).

Microfiltration (MF)

The MF membrane process is used for withholding the particles suspended in water, much like conventional coarse filtration in which pressure acts as a driving force that works to remove suspended solids (Meng et al. 2019). MF membranes are fairly efficient at removing colloidal matter and solid particles suspended in water, where about 40% of organic matter can be retained by the membrane (Kumar et al. 2019). Media or membrane filtration has also been shown to reduce turbidity and organic matter in spring water that is rich in dissolved minerals.

MF is generally divided into two membrane separation processes namely dead-end (DEF) filtration (with a single flow direction) and crossflow filtration (CFF) (with the bidirectional flow) (Teng et al. 2003). DEF is a method in which the feed is introduced perpendicularly to the surface of the membrane and filtered matter builds up on this layer, creating what amounts to a cake (Alexakis and Tsakiris 2013). With an increase in filtration time, the thickness of the formed cake layer increases, and consequently the rate of permeate recovery decreases. Only a portion of the water in the feed stream is treated and passed untreated through it; this lowers energy consumption because less downstream processing equipment may be required than for conventional treatment technologies (Meng et al. 2019).

Crossflow filtration is unique in the sense that there are two forces at work here, the first being a parallel force in which the filtration occurs as the feed suspension flows along the surface of the membrane and the second force being perpendicular to the flow which acts on the membrane itself—the trans-membrane pressure being the reason for the generation of this force (Alexakis and Tsakiris 2013). The crossflow mode of filtration is an advanced technique that can be used to concentrate liquid products and purify solutions (Kumar et al. 2016). The parallel-mode operation has numerous advantages, including low consumption of energy and an increase in the amount of yield. However, the perpendicular force is responsible for membrane gel layer formation—which is the material that is retained on the surface of the membrane, this is only possible when this mode is used in high concentrations of solvents with large molecules (Kumar et al. 2016).

DEF is mostly limited to small-scale usage essentially being employed in laboratories, while CFF is employed on a large scale by its use in industries such as desalination (Alexakis and Tsakiris 2013). DEF is a simple method of concentration that relies on an increase in temperature to drive the process (Alexakis and Tsakiris 2013). It is similar to conventional filtration: Filtrate passes through a membrane while matrix material remains on one side (Tang et al. 2019). Conversely, in CFF, materials move past each other in crossflow arrangement: with permeate and retentate flowing in opposite directions (Park et al. 2005).

In MF, membranes with pore sizes ranging from 50 to 800 nm are typically used at pressures of about 3 bar (Kumar et al. 2019). This makes them exemplary for the separation of suspensions, blends, mixtures, and emulsions as shown by the fact that it can retain particles that are about the size 104–102 nm. Therefore, it can remove even the smallest suspended particles, such as bacteria, algae, and protozoa (Mountoumnjou et al. 2022).

In MF, the full thickness of a porous membrane may hinder transport across it. The thickness of MF membranes can be quite large—they are often between 10 and 150 microns (Tang et al. 2019). Although most MF membranes have a top-layer thickness of about 1micron, the underlying structure can be unevenly built up. Inorganic materials (ceramics, metals, or glass) are used in their manufacture; organic polymers may also play a role (Jedidi et al. 2022).

The manufacturing of MF membranes involves several techniques, including sintering and stretching. Symmetrical pore structures are usually produced with porosities ranging from 75 to 80% (Tang et al. 2019). MF membrane modules are most commonly made from high-density polyethylene, glass fiber-reinforced plastic, polypropylene, polycarbonate or ceramics. However, ceramic MF membranes may also be used in certain applications where the need arises to remove much smaller particles.

MF membranes have the largest pore size of all membrane filtration systems (0.1–3 microns), while UF membranes have smaller pores ranging from 0.01 to 0.1microns in diameter (Meng et al. 2019). MF provides a good balance between UF and granular media filtration. It filters particles of intermediate size, lying in the lower end of clays’ particle-size distribution but above humic acids. This is too small for bacteria, algae, and cysts but large enough to trap viruses (Meng et al. 2019).

Both MF and UF membranes have been used in drinking water filtration for several purposes. One such use is to reduce turbidity, but they are also effective at removing some microorganisms like Giardia and Cryptosporidium as well as certain organic compounds produced by algae (Meng et al. 2019). In addition, they are also used in distillation, and evaporation which require low pressure to operate—1 to 30 psi. Furthermore, they are also used as a pretreatment step before desalination.

Activated carbon filtration (ACF)

The use of activated carbon for water purification and medicinal purposes can be dated back to Ancient Egypt, where its adsorbent characteristics were recognized around 1500 B.C. (Bull 1980). Swedish scientist Carl Wilhelm Scheele first reported in the late eighteenth century that charcoal could adsorb gases such as oxygen, nitrogen, and carbon dioxide (Bull 1980). In recent decades, activated charcoal has been used by the industry for its decolorizing properties.

Recently, numerous plants have been developed that produce activated carbon for wastewater treatment. ACF remove many types of contaminants from air and water, including heavy metals and sediments without leaving any residual taste or odor behind (Junoh et al. 2016). ACFs do not break down contaminants into smaller particles but simply absorb them making it a hybrid technique of chemical treatment and membrane filtration (Abdulrahman et al. 2012).

Activated carbon is a substance derived from coal and other fossilized organic materials that have been chemically “activated” by heating it in the presence of certain chemicals (Ismadji and Bhatia Jul. 2001). This process often occurs at temperatures of more than 600 °C but can be induced at lower temperatures by using specific catalysts and conditions (Ismadji and Bhatia Jul. 2001). They are made of activated carbon, a material that has been treated with chemicals to produce pores on its surface (Spellman and Drinan 2012). These tiny pores allow gases to escape as long as particles are not stuck in the pores (Spellman and Drinan 2012). The pores create a filter to trap and remove impurities from the water as it passes through by adsorption.

ACFs are usually made from several layers of activated carbon, which are stacked together in a way that allows them to absorb different kinds of impurities: heavy metals like lead, mercury, or cadmium; dissolved inorganic and organic compounds like proteins or hormones; and bacteria (Marsh and Rodríguez-Reinoso 2006). Additionally, salts, organic compounds such as pesticides or herbicides, or even bacteria are also removable. They can also remove particulate matter like rust and iron oxide from water as well as protozoan cysts (Allwar et al. 2011).

Activated Carbon has such a fine structure that the pore surface area of each gram is greater than 1000 m2 (Stevenson 1997). This provides powerful adsorptive properties. Carbon in different forms, powder, granular, or pellet is usable. Although granular and powdered activated carbon is the most commonly used forms, other types have also been explored by researchers (Stevenson 1997). Activation of coal occurs via two methods: physical or chemical (Janoš et al. 2009).

The most common ACF is zeolite, which are naturally occurring minerals that have pores which are too small for bacteria to enter. This makes them effective at removing bacteria, viruses, and other pathogens from water while leaving behind only beneficial minerals (Nuithitikul et al. 2010). Zeolites can also be used to reduce acidity in tap water. Another common type of activated carbon filter is made from polysaccharides such as sugar cane bagasse and coconut husks. Polysaccharides are capable of reducing turbidity levels by removing particles suspended within the water column—which helps improve taste and clarity of water (Nuithitikul et al. 2010). Activated carbon is usually made by heating wood or coal in an oven at high temperatures until it becomes very porous. It is then poured into molds and allowed to cool. The ACF is usually made from granular activated charcoal and contains an ion exchange resin (Da̧browski et al. 2005), which work together to remove impurities from the water being purified (Bae et al. 2014). Activated charcoal is a porous material with an extremely high surface area and low bulk density, which allows it to adsorb many different types of molecules (Boopathy et al. 2013). Other sources of activated carbon include fiber, made primarily from petroleum pitch and carbon; felt (for clothing)–a textile with a soft, dense surface on the inside of its fabric; ash—the remains following combustion or fire (Stevenson 1997).

Various studies have reported the use of agricultural wastes, such as rice husk, jujube seeds, and sawdust, in addition to tropical wood pulp from plants like coconut/palm shells and durian peel fibers to make ACFs (Heidarinejad et al. 2020). Although agricultural waste products like walnut shells, watermelon husks (Rahman et al. 2013), tobacco stems, and bean hulls have been used many non-agricultural sources of activated carbon materials (such as automobile tires) are now being found (Ioannidou and Zabaniotou 2007; Kumar and Porkodi 2009). In a recent test of Brazil nut-derived activated carbon suitability as a bioactive sorbent for removing fluoride from water, the material was kept at a high temperature for 2 h and has shown promising results (Matheickal and Yu 1999).

ACFs are simple to design, operate and scale up; selective toward certain substances; and capable of removing pollutants from even dilute solutions. They can also be used to reduce certain chemical odors and tastes that may be present in air or water. This type of filter is especially effective at removing hydrogen sulfide gas that can cause a rotten egg odor in water (Boopathy et al. 2013). Activated carbon is considered to be safe by the FDA, and its use in water filtration systems has been approved by the U.S. Environmental Protection Agency (EPA) (Foo and Hameed 2009). The process of ion exchange removes contaminants from drinking water, but it also removes beneficial minerals like calcium and magnesium. The ACF can be used in any type of application, including industrial or commercial applications as well as in residential or household settings (Leimkuehler 2010).

Applications

Water sourced from groundwater, seawater, and sewage water may contain impurities that must be eliminated before it can be used for various purposes, such as drinking, irrigation, or industrial activities.

Groundwater can be contaminated with nitrates, arsenics, fluorides, and other minerals. To treat groundwater, RO, UF, and MF systems are commonly used. RO systems are highly effective in removing dissolved salts and minerals, making it an ideal solution for desalination, whereas UF and MF systems can remove suspended solids, bacteria, viruses, and other pathogens, as well as sediment and organic matter.

Seawater is an important source of water, especially in coastal regions where freshwater sources are scarce. However, seawater contains high levels of dissolved salts and minerals, making it unsuitable for drinking and other uses. To treat seawater, RO systems are the most used filtration technology. RO systems are highly effective in removing dissolved salts and minerals, as well as bacteria, viruses, and other pathogens. RO systems can achieve removal rates of up to 99%, making them ideal for desalination.

Sewage water also necessitates treatment before reuse. This type of water comprises substantial amounts of organic matter, pathogens, and other pollutants. To purify sewage water, ACF, UF, and MF are frequently utilized. ACFs can remove organic compounds, chlorine, and pesticides. Meanwhile, UF and MF systems can extract bacteria, viruses, suspended solids, organic matter, and sediment.

The effectiveness of different types of filtration systems in removing impurities from ground, sea, and sewage water are summarized in Table 1.

Table 1 Overview of research of different membrane filtration techniques for water purification
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RO is notably efficient in the removal of salts, minerals, and other contaminants, which makes it ideal for purifying seawater. This has resulted in its dominant position in the water purification technology used in desalinating seawater and brackish water (Lee et al. 2010). It is highly competent in eliminating bacteria, viruses, and suspended solids, thus making it an ideal system for groundwater purification. On the other hand, UF is an efficient system for removing impurities from water, especially in the treatment of groundwater. Similarly, MF is also effective in removing bacteria and viruses and can operate at low pressure, making it ideal for treating groundwater, making it a cost-effective and efficient system for removing impurities from groundwater. However, MF is not effective in removing dissolved solids and organic contaminants, limiting its usefulness for seawater purification. Like MF, UF also has limited effectiveness in the removal of dissolved solids and organic contaminants, which limits its usefulness in seawater purification.

The popularity of MF membranes is ever growing especially in the wastewater industries where they are used to remove particles from sewage treatment and also heavy-polluted industrial wastewater (Ahn and Song 1999). A study found that mild oxidation in combination to MF is a viable alternative to air stripping for removing gaseous hydrogen sulfide from groundwater (Al-Malack and Anderson 1997). Suspended solid particles, microorganisms, and algae can be completely removed from wastewater by applying adequate primary treatment using ceramic MF membranes (Ahn and Song 1999). This reduces the amount of chlorine needed to meet water quality standards for safe transport and distribution (Jepsen et al. 2018).

In summary, RO is best suited for desalinating seawater, while MF and UF are effective in removing impurities from groundwater. ACF is ideal for treating drinking water but less effective in removing dissolved solids and inorganic compounds.

Potential and outlook

An overview of the pros and cons of each technique are discussed in Table 2.

Table 2 Advantages and disadvantages of each membrane filtration technique
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RO system consumes significant energy to function, and its wastewater contains a high level of salts and other contaminants. In contrast, UF membranes have an advantage over RO for treating large volumes of water. UF is used in many areas, including the production of extremely pure water for use in electronics manufacturing and recycling of paints containing charged particles, juice, or beverage production as well as food industry water, pharmaceutical and medical industries (Qi, et al. 2011). UF is also used to remove heavy metals in industrial applications such as smelting plants and metal fabrication facilities, where there's a need for clean raw materials (LeChevallier and Au 2013). UF is ideal for oil exploration sites where there’s an interest in recovering hydrocarbons from deep underground layers where they’ve been trapped by geological conditions such as tectonic plates shifting over millions of years (LeChevallier and Au 2013).

MF is well suited for industrial applications in which the retention of particles greater than 0.1microns from mixed solutions must be ensured. Sterilization and clarification are two examples of how it is used in various industries, including the food, pharmaceutical, and feed industries (Ahn and Song 1999). Studies have been done to determine whether MF can remove parasites such as Giardia or Cryptosporidium. It was found that ultrasonic waves coupled with MF membranes do effectively reduce parasite numbers (Meng et al. 2019).

ACF is effective in removing organic compounds and chlorine, making it ideal for treating drinking water. However, ACF is less effective in removing inorganic compounds and dissolved solids, and it requires periodic replacement of the filter.

In terms of effectiveness, RO is the most effective in removing salts and minerals, while MF and UF are effective in removing microorganisms. ACF is most effective in removing organic compounds and chlorine. Factors that determine which membrane should be selected include cost, purity of water recovered (percentage), the percentage of impurities rejected by the filter, characteristics of raw water sources, and whether pretreatment will be required—everything from chlorination to seawater desalination (Meng et al. 2019). A summary of the effectiveness of each filtration process is presented in Fig. 3:

Fig. 3
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An overview of the effectiveness of membrane-based filtration techniques (Liao et al. 2018)

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Conclusion

The demand for clean and safe drinking water has led to the development of various filtration systems, where each has unique features and benefits that make them suitable for specific water filtration needs. An extensive examination of various filtration methods was conducted to achieve a particular goal of evaluating the effectiveness and practicality of different techniques. These techniques included reverse osmosis, ultrafiltration, microfiltration, and activated carbon filtration, each of which has specific benefits and drawbacks. Filtration systems play a crucial role in multiple industries, including but not limited to food and beverage, pharmaceutical, and chemical.

The effectiveness of various filtration systems depends upon the water source. RO is very effective in removing salt and minerals, whereas MF and UF remove micro-organisms efficiently. Looking at the problem from the practical point of view, it can be reasoned that the RO system is appropriate for desalinating sea water. Conversely, MF and UF systems can be more suitable in removing impurities from groundwater. On the other hand, ACF can deal with taste and odor problems in drinking water, but lags when it comes to the removal of dissolved solids and inorganic compounds.

Overall, when it comes to choosing a filtration system, there are several factors to consider, such as the type of contaminants in the water, the flow rate, and the required level of filtration.