A new hybrid Vetiver system for the treatment of polyphenol-rich wastewater from olive oil production

Abstract

This study demonstrates that Vetiveria zizanioides (Vetiver grass) can effectively remediate wastewater enriched in polyphenols, a major pollutant from olive-oil production. High phenolic and organic loads pose serious environmental risks and challenge conventional treatment methods. To address this, we developed an innovative hybrid treatment prototype at the Fez wastewater plant, combining trickling filters, planted filters, and activated sludge with vetiver’s extensive root system and active aeration. Wastewater containing 40–100 mg/L polyphenols was applied, and daily measurements of phenols, pH, dissolved oxygen, nitrogen, phosphorus, and chemical oxygen demand (COD) were recorded over eleven days. Unlike previous studies, this research tested high pollutant loads, implemented the system at a real wastewater treatment facility, and monitored multiple parameters daily to provide detailed pollutant-removal dynamics. Results revealed substantial removal: 91% COD, 87.5% phenols, 94.1% nitrogen, and 80.72% phosphorus, while vetiver maintained healthy growth under high contamination. These findings highlight the resilience and strong phytoremediation capacity of vetiver, demonstrating a scalable, cost-effective, and environmentally sustainable alternative to conventional wastewater treatment. The study advances current knowledge by combining hybrid treatment systems, real-world application, and high-load testing, supporting municipalities and industries in improving wastewater management, reducing treatment costs, and mitigating environmental impacts.