Chitosan in Water Filtration: Cleaner, Safer, and More Sustainable Solutions

Could chitosan be integrated into common home water filters to more effectively remove a wide range of contaminants? [Designed by Freepik]

I. Introduction

Access to clean, safe drinking water is a fundamental human right and a cornerstone of public health. Yet, across the globe, communities grapple with the persistent challenge of water contamination, ranging from industrial pollutants and agricultural runoff to emerging contaminants like microplastics. This pervasive issue has driven a significant demand for effective water purification solutions, leading to the widespread adoption of household filtration systems, such as popular BRITA-style filters, and large-scale industrial treatment plants.

While these conventional filtration methods have played a crucial role in safeguarding water quality, they are not without their limitations. Activated carbon filters, a staple in many household and industrial systems, excel at removing chlorine, odors, and certain organic compounds. However, their efficacy can be compromised by high levels of contamination, leading to rapid saturation and a diminished lifespan (Cascade Designs). Moreover, they are not universally effective against all pollutants, often failing to remove heavy metals, nitrates, or certain microbial contaminants.

Ion-exchange resins, another common filtration technology, are highly effective at softening water by removing hardness ions like calcium and magnesium. They can also be engineered to target specific contaminants, such as nitrates or sulfates. However, these systems often have a limited capacity and require frequent regeneration, a process that can be resource-intensive and generate brine waste (ElectraMet). Furthermore, they typically do not remove bacteria, viruses, or larger particulate matter, necessitating their use in conjunction with other filtration stages.

A discarded plastic bottle, a common sight, highlights the pervasive issue of plastic pollution. This waste breaks down into microplastics, a growing contaminant that conventional water filters struggle to remove.

Perhaps one of the most pressing concerns with conventional filters in recent years is their limited ability to address the growing threat of microplastics. These ubiquitous pollutants, originating from the breakdown of larger plastic items and various industrial processes, are increasingly found in water sources worldwide. Many standard filters are simply not designed to capture these microscopic particles, raising concerns about their potential long-term health and environmental impacts (da Costa et al., 2024). Additionally, the relatively short lifespan of many household filter cartridges contributes to plastic waste, counteracting the very sustainability goals many consumers aim to achieve.

In light of these challenges, there is a clear and urgent need for innovative, sustainable, and highly effective water purification technologies. This article explores the remarkable potential of chitosan, a natural biopolymer derived from chitin, as a transformative solution for cleaner, safer drinking water. We will delve into its unique properties, examine its known and potential applications in water filtration, and highlight how it can address the shortcomings of existing systems, offering a more sustainable and comprehensive approach to water treatment.

II. Properties and Applications of Chitosan in Water Purification

Chitosan is a linear polysaccharide composed of randomly distributed β-(1→4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). It is derived from chitin, the second most abundant natural polymer after cellulose, found primarily in the exoskeletons of insects and crustaceans (e.g., crabs, shrimp), as well as in the cell walls of fungi. Its unique chemical structure, particularly the presence of free amino groups, bestows upon it a remarkable array of properties that make it highly effective in various applications, including water purification.

1) Adsorption of Heavy Metals & Heavy Metal Removal

One of chitosan's most significant attributes in water treatment is its exceptional ability to adsorb heavy metal ions. The positively charged amino groups (–NH3+) on the chitosan backbone readily interact with negatively charged heavy metal ions (e.g., lead, cadmium, mercury, copper) through electrostatic attraction, chelation, and ion exchange mechanisms (Ashraf et al., 2024). This makes chitosan an effective biosorbent for removing these toxic contaminants from water. Research has shown that modified forms of chitosan, such as those incorporating magnetic nanoparticles or graphene oxide, can further enhance its adsorption capacity and efficiency, allowing for easier separation and recovery of the adsorbed metals (Wang et al., 2023; El-Gamel et al., 2025).

Chitosan has been extensively studied and implemented for the removal of heavy metals from industrial wastewater and contaminated groundwater. Its high affinity for metal ions, particularly transition metals and metalloids, makes it an excellent alternative to conventional chemical precipitation or ion exchange methods. Chitosan-based biosorbents, often in the form of beads, flakes, or membranes, have been successfully used to treat effluents from mining operations, electroplating industries, and battery manufacturing, significantly reducing the concentration of toxic heavy metals before discharge (Ashraf et al., 2024).

2) Antimicrobial Activity & Bacterial Control in Treatment Plants

Chitosan's inherent antimicrobial properties make it a powerful ally in water purification, preventing the proliferation of bacteria and biofouling in filters and treatment infrastructure.

Chitosan exhibits broad-spectrum antimicrobial activity against a wide range of bacteria, fungi, and some viruses, making it a valuable agent for disinfecting water. The polycationic nature of chitosan allows it to interact with the negatively charged components of microbial cell membranes, leading to increased permeability, leakage of intracellular components, and ultimately, cell death (Ke et al., 2021). The effectiveness of chitosan as an antimicrobial agent is influenced by factors such as its molecular weight, degree of deacetylation, and concentration. This inherent antimicrobial property can help in controlling bacterial growth in water treatment systems and preventing biofilm formation.

Given its inherent antimicrobial properties, chitosan has found applications in controlling bacterial growth within water treatment processes. It can be used as a natural disinfectant or as a component in filter media to prevent biofouling, a common problem in membrane filtration systems that reduces efficiency and increases maintenance costs. By inhibiting the proliferation of harmful microorganisms, chitosan contributes to the overall microbiological safety of treated water and extends the lifespan of filtration infrastructure (Molina-Pinna & Román-Velázquez, 2025).

3) Removal of Dyes & Dye Adsorption

Industrial effluents often contain various synthetic dyes that are highly colored, toxic, and difficult to degrade. Chitosan's positively charged amino groups and hydroxyl groups enable it to effectively adsorb anionic and some cationic dyes from wastewater through electrostatic interactions, hydrogen bonding, and hydrophobic interactions (Waliullah et al., 2023). Studies have demonstrated chitosan's high efficiency in removing a wide array of dyes, including reactive dyes, acid dyes, and basic dyes, making it a promising and environmentally friendly alternative to conventional chemical coagulants for dye removal (Vakili et al., 2014).

The textile, paper, and food industries generate large volumes of wastewater containing synthetic dyes, which are aesthetically displeasing and often carcinogenic. Chitosan's effectiveness in adsorbing various types of dyes has led to its application in treating such industrial effluents. Its ability to form strong bonds with dye molecules, coupled with its biodegradability, makes it an environmentally friendly and cost-effective solution for color removal. Chitosan-based systems can achieve high removal efficiencies, contributing to cleaner discharge and potential water reuse (Waliullah et al., 2023).

4) Removal of Pesticides

Pesticides, used widely in farming, can leach into groundwater and rivers. Chitosan and its derivatives have shown considerable potential in removing these toxic molecules.

Pesticides, widely used in agriculture, can contaminate water sources and pose significant environmental and health risks. Chitosan and its derivatives have shown considerable potential in removing various types of pesticides from water. The adsorption mechanisms involve electrostatic interactions, hydrogen bonding, and hydrophobic interactions between the pesticide molecules and the active sites on the chitosan structure (Shuang et al., 2022). This capability is crucial for ensuring the safety of drinking water and preventing ecological damage from agricultural runoff.

5) Removal of Microplastics

As highlighted earlier, microplastic pollution is a growing global concern. Chitosan offers a sustainable and effective solution for the removal of these pervasive contaminants. Its positively charged nature allows it to bind with negatively charged microplastic particles through electrostatic attraction, leading to flocculation and subsequent sedimentation or filtration (Huang et al., 2023). This mechanism is particularly effective for a broad spectrum of microplastic types, including polyethylene (PE) and polypropylene (PP), which are common in plastic waste (Putranto et al., 2023). The ability of chitosan to effectively capture microplastics positions it as a key material in addressing this emerging environmental challenge.

6) Potential & Point-of-Use/Process Integrations

Household water filters

The integration of chitosan into household water filters presents a significant opportunity to enhance their performance and address consumer concerns. By incorporating chitosan into existing activated carbon or ceramic filter cartridges, manufacturers could develop filters capable of removing a broader spectrum of contaminants, including heavy metals, pesticides, and microplastics, which are often missed by conventional filters. This would provide consumers with a more comprehensive and reliable solution for ensuring the safety of their drinking water at home.

Industrial wastewater treatment

Industrial wastewater, often a mix of complex contaminants, can be effectively treated with chitosan, which acts as a natural coagulant to remove a wide range of pollutants [Image by Adobe Stock]

Beyond its current applications, chitosan holds immense potential for broader adoption in industrial wastewater treatment. Its ability to flocculate suspended solids, adsorb diverse pollutants, and exhibit antimicrobial activity makes it suitable for treating complex industrial effluents from various sectors, including pharmaceuticals, petrochemicals, and food processing. Chitosan-based systems could offer more sustainable and efficient alternatives to chemical-intensive processes, leading to reduced sludge generation and improved effluent quality.

Desalination pre-treatment

Desalination plants, which convert seawater or brackish water into fresh water, often face challenges with membrane fouling caused by suspended solids, organic matter, and microorganisms. Chitosan can serve as an effective pre-treatment agent, acting as a natural coagulant and flocculant to remove these foulants before the water enters the sensitive reverse osmosis membranes. This would reduce the frequency of membrane cleaning, extend membrane lifespan, and lower operational costs, making desalination more efficient and economically viable.

Emergency water purification kits

In disaster relief scenarios or remote areas lacking access to safe drinking water, portable and effective water purification solutions are critical. Chitosan's ability to remove a wide range of contaminants, including pathogens, heavy metals, and suspended particles, makes it an ideal candidate for inclusion in emergency water purification kits. Its natural origin, biodegradability, and ease of use could provide a simple yet powerful tool for rapidly producing safe drinking water in challenging environments.

7) Addressing Consumer Frustrations with Current Filters

Limited lifespan

By enhancing the removal efficiency of various contaminants, chitosan could potentially extend the effective lifespan of filter cartridges, reducing the frequency of replacements and associated costs.

Inability to remove all contaminants

As demonstrated, chitosan can target pollutants like heavy metals, pesticides, and microplastics that many standard filters struggle with, providing a more comprehensive purification solution.

Environmental waste from cartridges

As a natural, biodegradable polymer, chitosan offers a more sustainable alternative to synthetic filter media. Its integration could lead to the development of more environmentally friendly filter cartridges, reducing plastic waste and promoting a circular economy approach to water filtration.

III. Conclusion

In an era defined by increasing environmental consciousness and growing concerns over water quality, the search for sustainable and effective water purification solutions has never been more critical. While conventional filtration methods have served us well, their inherent limitations, particularly in addressing emerging contaminants like microplastics and their contribution to waste, underscore the urgent need for innovation.

Chitosan, with its remarkable properties as a natural flocculant, potent adsorbent, and broad-spectrum antimicrobial agent, emerges as a truly promising biopolymer for revolutionising water treatment. Its ability to effectively remove heavy metals, dyes, pesticides, and crucially, microplastics, positions it as a versatile and environmentally friendly alternative or complement to existing technologies. From enhancing household water filters to optimising industrial wastewater treatment, and even enabling emergency purification, chitosan offers a pathway to cleaner, safer water for all.

At Entoplast, we are at the forefront of harnessing the power of this extraordinary natural resource. As a leading UK-based manufacturer of high-quality chitin and chitosan, we are dedicated to supplying the foundational ingredients that can transform water purification systems globally. We believe that collaboration is key to unlocking the full potential of chitosan in addressing the world's water challenges.

We invite academics, water treatment professionals, and industry experts to explore the myriad applications of our high-quality chitin and chitosan. Let us work together to integrate this natural solution into the next generation of water filters and industrial systems, reducing reliance on purely synthetic solutions while offering superior contaminant removal and fostering true sustainability.

To learn more and discuss how Entoplast can support your innovations in water treatment and consumer filters, please contact us through our website's contact form or email us directly at hello@entoplast.com.