A biochar system for low-cost, high volume aqueous nitrate removal

Overview

Nitrate contamination of water supplies is a significant public health concern, particularly in developing countries and rural areas where conventional filtration infrastructure is often unavailable or unaffordable. This solution presents a scalable, low-cost biochar filtration system designed for high-volume aqueous nitrate removal. By leveraging locally sourced plant and agricultural waste converted into biochar, the system provides an accessible water treatment approach while creating a circular benefit: exhausted biochar cartridges can be repurposed as nutrient-rich fertilizer.

Technical specifications

Core technology and design:

• Filtration media is elephant grass-derived biochar prepared at 600 degrees Centigrade, which prior research has shown can achieve adsorption capacities of approximately 237.5 mg per gram
• The filtration tank is configured at a ratio of 1 liter per 100 grams of biochar, with inlet and outlet ports designed for a flow rate of 10 liters per second
• Flow rates can be adjusted up or down based on specific site requirements and user needs
• The system uses replaceable biochar cartridges that can be swapped out and recycled as fertilizer once nitrate-saturated

Key advantages:

• Biochar is reliably available in large quantities and can be produced locally from common plant and agricultural waste
• The approach targets compliance with the World Health Organization threshold of less than 50 mg/L nitrate-nitrogen in drinking water
• Fully scalable for both low and high flow rate applications
• Site-specific optimization is possible by researching locally available plant wastes for ideal biochar production

Technology readiness level

The system is currently at an early-to-mid stage of development. The proposed validation pathway includes conducting artificial filter and tank tests based on water runoff flow rates equivalent to a 100-year storm event, followed by optimization of biochar cartridges for flow rate and lifespan through both simulation and experimental testing. Additional validation will assess the viability of expended cartridges as fertilizer. A pilot study in local communities is planned as the final validation step, with further system optimization as needed based on field results. The underlying biochar adsorption science is well-established in published literature, providing a strong foundation for applied development.