Chitosan vs. Synthetic Polymers in Wastewater Treatment: Expanding the Plastic Pollution Dialogue through a Comparative Study on Performance, Environmental Impact, and Circular Economy

Discussions on plastic pollution have predominantly focused on solid and water-insoluble polymers, such as polyethylene and polystyrene, spanning from large debris to microplastics. However, there is another category that has been largely overlooked: non-solid polymers used as flocculants.

Synthetic polymers used as flocculants in wastewater treatment can harm marine ecosystems in several ways: toxicity and bioaccumulation, disruption of natural aggregation processes and alteration of water quality posing a multi-faceted threat to marine ecosystems.

In recent years, there has been a growing interest in sustainable alternatives for wastewater treatment, particularly in reducing reliance on synthetic polymers as flocculants. Synthetic polymers’ environmental and potentially toxic residuals underscore the urgent need for biodegradable and eco-friendly alternatives.

 Chitosan, a biopolymer derived from shrimp shell waste, has shown potential as an effective natural flocculant.

This study evaluates chitosan’s flocculation performance compared to synthetic polymers through a series of jar tests to determine optimal dosing, turbidity reduction, and solid-liquid separation efficiency. In this study, real wastewater samples were used to evaluate chitosan’s effectiveness as a natural flocculant, ensuring practical relevance and enhancing the validity of the results. By using actual wastewater rather than simulated solutions, the research assessed chitosan’s performance under real-world conditions, which often include complex mixtures of organic and inorganic pollutants. This approach allowed for a more accurate comparison between chitosan and synthetic polymers, providing insights into chitosan’s practical feasibility and efficacy in diverse wastewater treatment scenarios. These findings suggest that chitosan is not only effective in reducing water turbidity but also supports efficient sludge management with lower moisture in the resulting dry cake.

Chitosan has demonstrated comparable efficacy to synthetic polymers in flocculation processes for wastewater treatment demonstrating chitosan's effectiveness as a feasible replacement.

Chitosan, repurposed from shrimp shell waste, embodies a circular economy approach by diverting biowaste from disposal and contributing to sustainable wastewater treatment.

As the world focuses primarily on solid plastic pollutants in oceans, this work aims to expand this dialogue to include other forms of synthetic polymers. This transition towards bio-based flocculants aligns with global sustainability goals and supports ocean health, as treated wastewater and synthetic polymers (flocculants) residues often ultimately enter marine ecosystems. By adopting chitosan, wastewater treatment facilities can reduce their reliance on non-renewable resources, mitigate pollution, and contribute to healthier aquatic ecosystems.