Optimizing Microwave-Enhanced Hydrogen Peroxide Treatment for Sludge Remediation: Impact on Nutrient Removal and Organic Pollutant Degradation

This study explores the use of microwave-enhanced hydrogen peroxide (H₂O₂) treatment for sludge remediation in wastewater management, focusing on the degradation of organic pollutants and nutrient removal efficiency. Secondary aerobic sludge samples were collected from a municipal wastewater treatment plant in Tikrit and subjected to a factorial experimental design with 12 treatment combinations, each replicated five times, totaling 60 treated samples plus five controls. Varying amounts of 30% w/w H₂O₂ were added prior to microwave irradiation. Post-treatment, samples were centrifuged and analyzed for parameters such as pH, chemical oxygen demand (COD), total phosphorus (TP), total Kjeldahl nitrogen (TKN), and ammonia nitrogen (NH₃-N). Results indicated that optimal conditions (50°C, 6 minutes, 4 mL H₂O₂) significantly enhanced sludge remediation, achieving 86.2% COD and 51.5% TP removal. However, higher temperatures (90°C) led to TP rebound (+11.5%) due to thermal solubilization, and NH₃-N levels surged by 2213%, reflecting a trade-off between organic degradation and nitrogen mineralization. Moderate conditions (70°C, 2 minutes, no H₂O₂) achieved maximum TP removal (75.8%). Statistical analyses identified temperature as the most influential factor, with H₂O₂ dosage further promoting oxidative degradation. Notably, acidification (pH 4.3–4.9) was observed, indicating the importance of balanced parameter optimization to prevent undesirable byproduct formation. Overall, microwave-H₂O₂ treatment appears to be a promising eco-friendly approach for wastewater treatment, with optimal conditions notably at 50°C, 6 minutes, and 4 mL H₂O₂, although further research is necessary to refine parameters and mitigate challenges related to ammonia byproducts and process scalability.