Recovering Phosphate from Complex Wastewater Using Macroporous Cryogel Composited Calcium Silicate Hydrate...

Area of Science:

• Environmental Chemistry
• Materials Science
• Water Treatment

Background:

• Nonrenewable phosphorus resources face depletion within 30-200 years, necessitating efficient recovery methods.
• Phosphorus-rich residues, including complex wastewater, are potential sources for recovery.
• Developing sustainable methods for phosphorus recovery is critical for resource management and environmental protection.

Purpose of the Study:

• To investigate phosphorus recovery from complex wastewater using continuous adsorption.
• To evaluate the efficacy of cryogel columns composited with calcium silicate hydrate nanoparticles (CSH columns) for phosphate adsorption.
• To analyze the factors influencing adsorption capacity and performance.

Main Methods:

• Continuous adsorption experiments were conducted using CSH columns.
• Phosphate recovery was tested on synthetic wastewater, household laundry wastewater, and reverse osmosis concentrate.
• Adsorption kinetics were modeled using the Yoon-Nelson and Adams-Bohart models.
• The influence of flow rate, initial concentration, column height, and interfering ions (carbonate, nitrate, sulfate) was assessed.

Main Results:

• Over 99% phosphate recovery was achieved from synthetic samples, 82.82% from laundry wastewater, and 97.58% from RO concentrate.
• Adsorption capacity increased with initial concentration and column height but decreased with flow rate.
• The Yoon-Nelson model provided a better fit for the experimental data (R² = 0.7723-0.9643) compared to the Adams-Bohart model (R² = 0.6320-0.8899).
• Carbonate ions significantly reduced phosphate adsorption performance (3.65 times decrease), while nitrate and sulfate had no notable effect.

Conclusions:

• CSH columns demonstrate high efficiency for continuous phosphate adsorption and recovery from diverse wastewater streams.
• The CSH column shows significant potential for sustainable phosphorus recovery, mitigating resource depletion.
• Understanding the impact of interfering ions like carbonate is crucial for optimizing real-world wastewater treatment applications.