Greywater Treatment with Activated Carbon and Biochar

A study compared activated carbon (AC) and biochar (BC) for greywater treatment, finding AC better for removing chemical oxygen demand and anionic surfactants, while BC excelled with non-ionic surfactants. Both materials effectively treated greywater for reuse, with BC offering a sustainable, cost-effective option.

October 5, 2024

1–2 minutes

Faggiano, et al (2025) Comparative study of greywater treatment using activated carbonActivated carbon is a form of carbon that has been processed to create a vast network of tiny pores, increasing its surface area significantly. This extensive surface area makes activated carbon exceptionally effective at trapping and holding impurities, like a molecular sponge. It is commonly More and woodchip biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More for surfactant and organic matter removal. *Separation and Purification Technology.* https://doi.org/10.1016/j.seppur.2024.129861

Greywater (GW) treatment is essential for water reuse and sustainability, particularly in water-scarce regions. A recent study compared the effectiveness of activated carbon (AC) and woodchip biochar (BC) in removing contaminants such as chemical oxygen demand (COD) and surfactants from GW. Surfactants, commonly used in cleaning products, pose environmental risks and need efficient removal for safe greywater reuse.

The study found that both AC and BC are effective adsorbents for GW treatment, but they excel at different tasks. AC demonstrated superior performance in removing COD and anionic surfactants (ASU), while BC was more effective at removing non-ionic surfactants (NISU). This makes biochar an attractive, cost-effective option for short-term applications where non-ionic surfactants are the primary concern. However, AC offers greater longevity and higher overall capacity for treating water with high organic content and anionic surfactants.

Both treatments reduced contaminant levels to meet Italian and Australian standards for non-potable water reuse, making treated greywater suitable for applications like irrigation or cleaning. Biochar, produced from low-cost, sustainable feedstocks, offers an environmentally friendly alternative to the more expensive and resource-intensive AC, particularly for short-term or specific pollutant removal needs.

This study highlights the potential for biochar to serve as a sustainable option for greywater treatment, contributing to water conservation and reuse in urban settings.