Impregnated pelletized activated carbon for phosphorus and nitrogen removal

Overview

This solution offers an advanced water treatment media that removes both phosphorus (P) and nitrogen (N) contaminants in a single filtration step. The impregnated pelletized activated carbon (IPAC) combines two complementary adsorption mechanisms: magnesium oxide additives on the carbon surface bind phosphorus, while basic oxygen functional groups selectively adsorb nitrate (NO3-). Aeration of the media further enhances nitrate removal, providing a more efficient and cost-effective approach to nutrient management compared to separate treatment processes.

The technology addresses a critical challenge for water utilities, agricultural operations, and environmental remediation projects where nutrient contamination is regulated or problematic. By consolidating two adsorption functions into one media, operators can reduce system complexity, footprint, and operating costs. Spent media retains value as a soil amendment for agricultural use, adding a circular economy benefit.

Technical specifications

Key features:

• Dual-nutrient adsorption: Removes phosphorus and nitrogen simultaneously using a single media
• Magnesium oxide additive: Binds phosphorus on the carbon surface, leveraging a patented removal technology currently in use at a Florida water treatment facility
• Surface chemistry optimization: Basic oxygen functional groups selectively adsorb nitrate ions; thermally treated basic carbons achieved 74% average nitrate removal compared to 41% for acidic carbons in batch testing
• Aeration enhancement: Air, oxygen, or nitrogen gas introduction improves nitrate adsorption, with air providing the best performance
• Gravity-fed design: Configured as a granular activated carbon (GAC) bed with adjustable bed volume to match treatment flow rates
• Agricultural reuse potential: Desorption properties allow spent media to serve as a soil amendment by-product

Performance data:

• Carbon dosage of 5 g/L achieved significant nitrate removal from a 20 mg/L solution in 30-minute contact tests
• Surface chemistry was identified as the key factor for nitrate selectivity rather than structural properties

Technology readiness level

The phosphorus removal component is already commercially deployed at a Florida water treatment facility. Batch-scale validation has confirmed the nitrate adsorption mechanism and the benefits of aeration. Future work will focus on developing the passive IPAC media, integrating the patented phosphorus technology with the nitrate adsorption media, and validating competitive adsorption of nitrogen and phosphorus, hydraulic performance, and adsorption kinetics. Optimization of dissolved oxygen operating conditions through aeration is also planned. The system is advancing toward pilot-scale demonstration as a gravity-fed GAC bed suitable for municipal, industrial, and agricultural water treatment applications.