Low-cost activated carbon from agricultural biomass for water desalination and pollutant removal

Overview

This technology offers an inexpensive, renewable alternative to traditional activated carbon for water desalination and pollutant removal. By converting agricultural residues such as corn stover, cobs, wood chips, and switchgrass into high-surface-area activated char through slow pyrolysis, the process delivers filtration and ion-removal performance at approximately one-third the cost of conventional activated carbon. The approach creates a circular benefit: agricultural producers supply the biomass feedstock and also gain access to affordable water treatment for their operations, while reducing reliance on fossil-fuel-derived carbon products.

Technical specifications

• Feedstock flexibility: Corn stover, corn cobs, wood chips, and switchgrass can all be processed, enabling regional sourcing of biomass.
• Pyrolysis-based production: Slow pyrolysis of agricultural residues produces biochar that is subsequently converted into activated char with high surface area and porosity at every filtration stage.
• Electrode and CDI configuration: Char-based electrodes have been fabricated and evaluated for desalination and electro-sorption of different ions, suitable for capacitive deionization (CDI) membrane or electrode configurations.
• Validated performance: Testing has demonstrated a ~50x reduction in mineral concentration of brackish water, bringing mineral content below 1%.
• Cost advantage: Activated carbon is produced at roughly one-third the cost of traditional activated carbon, making advanced water treatment economically viable for agriculture and rural communities.

Technology readiness level

The technology has progressed beyond initial concept validation. A prior reactor has been built and used to achieve high surface area and porosity across filtration stages, and char-based electrodes have been fabricated and tested for desalination and electro-sorption efficacy. Future validation will focus on producing activated biochars from multiple agricultural feedstocks and evaluating them in CDI membrane and electrode configurations for desalination performance. The research team is partnered with ARTI Inc. (Advanced Renewable Technology International), which has led thermochemical biochar treatment in Iowa and is positioned to advance the technology toward new milestones with continued funding.