Coir Fiber as a Sustainable Alternative to Polypropylene Water Filters: A Comparative Review

Abstract

Access to safe drinking water remains a major global challenge due to increasing contamination from industrialization, agricultural activities, and urbanization. Conventional water filtration systems commonly utilize polypropylene (PP) filter cartridges owing to their low cost and ease of manufacturing. However, the non-biodegradable nature of polypropylene contributes significantly to environmental pollution and plastic waste generation. Consequently, there is growing interest in the development of sustainable and eco-friendly filtration materials derived from natural resources. Among various natural fibers, coir fiber has emerged as a promising candidate due to its abundance, biodegradability, low cost, high lignin content, and excellent durability in aqueous environments. This review critically evaluates the potential of coir fiber as an alternative filtration medium for water purification applications. The physical, chemical, and mechanical properties of coir fibers are discussed and compared with conventional polypropylene filtration materials. Various fiber modification techniques, filtration mechanisms, environmental impacts, and sustainability considerations are reviewed. Existing research gaps and future directions for the development of coir-based filtration composites are also highlighted. Furthermore, the adoption of coir fiber-based filtration systems aligns with the objectives of the United Nations Sustainable Development Goals (SDGs), particularly SDG 6 (Clean Water and Sanitation), SDG 12 (Responsible Consumption and Production), SDG 13 (Climate Action), and SDG 15 (Life on Land), by promoting sustainable water treatment technologies, reducing plastic waste, supporting circular bioeconomy practices, and minimizing environmental impacts associated with conventional filtration materials.

Introduction

Water is essential for human health and development, yet millions of people still lack access to safe drinking water. Conventional water filtration systems commonly use synthetic materials such as polypropylene (PP), which effectively remove suspended particles but contribute to environmental pollution because they are non-biodegradable. Growing concerns about plastic waste have encouraged researchers to explore sustainable, biodegradable alternatives.

This review examines coir fiber, obtained from coconut husks, as an eco-friendly replacement for polypropylene filtration media. Coir is a renewable agricultural by-product that is abundant in tropical countries such as India, Sri Lanka, Indonesia, and the Philippines. It is biodegradable, durable, resistant to microbial attack, and performs well under wet conditions, making it a promising material for water filtration applications.

The paper first discusses conventional water filtration technologies, including:

• Polypropylene filters, which are widely used because of their durability, low cost, and chemical resistance but create long-term plastic waste.
• Activated carbon filtration, which effectively removes organic pollutants, chlorine, odors, and dissolved contaminants through adsorption but requires periodic replacement and does not eliminate all microorganisms or dissolved salts.
• Membrane filtration technologies such as microfiltration, ultrafiltration, nanofiltration, and reverse osmosis, which provide high contaminant removal efficiency but involve high energy consumption, maintenance costs, and membrane fouling issues.

The review then focuses on coir fiber as a sustainable filtration material. Coir possesses several desirable physical and chemical properties, including:

• High lignin content (40–45%), providing strength and microbial resistance.
• Cellulose and hemicellulose, which contribute to structural stability and contaminant interaction.
• A naturally porous and rough surface that enhances particle trapping and adsorption.
• High moisture resistance, durability, low density, and long service life in wet environments.

Compared with polypropylene filters, coir fiber offers significant environmental advantages. It is renewable, biodegradable, has a lower carbon footprint, utilizes agricultural waste, and supports circular economy principles. In contrast, polypropylene is petroleum-based, non-biodegradable, and contributes substantially to plastic pollution despite its durability and widespread availability.

The study explains that coir was selected because of its:

• Wide availability and low cost.
• Excellent mechanical strength and durability.
• Suitability for water-related applications due to high lignin content.
• Ability to promote sustainable development by reducing dependence on petroleum-based materials and utilizing agricultural waste.

The paper also describes the filtration mechanisms of coir fiber-based filters. Coir removes contaminants through:

• Mechanical filtration, where its porous structure traps suspended particles and reduces water turbidity.
• Adsorption, where cellulose, hemicellulose, and lignin interact with dissolved pollutants, organic compounds, dyes, and certain heavy metals.
• Surface modification techniques such as alkali treatment, which increase surface roughness and expose more active sites, improving adsorption efficiency and overall filtration performance.

Conclusion

The increasing environmental concerns associated with polypropylene filtration materials necessitate the development of sustainable alternatives. Coir fiber possesses several advantages, including biodegradability, abundance, low cost, and favorable mechanical properties. Current evidence suggests that coir fiber has significant potential as a filtration medium for water purification applications. Further research focusing on material optimization, durability, and large-scale implementation could facilitate the transition toward environmentally sustainable water filtration technologies.

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Copyright

Copyright © 2026 S. Krithika, Pragadheeswari R.. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.