Integrated Fixed-bed Column Adsorption And Solid-state Fermentation For Effective Removal Of Bisphenol A Using Biochar-based Biomaterials

Tunisia’s groundwater resources are increasingly threatened by overexploitation, salinization, and pollution from agricultural and industrial activities. A growing concern is the presence of Contaminants of Emerging Concern (CECs), including endocrine-disrupting chemicals like Bisphenol A (BPA), which originate from non-point source pollution and accumulate in soils and surface waters [1]. These persistent pollutants pose significant risks to both ecosystems and public health, highlighting the urgent need for innovative and sustainable remediation strategies. Biochar has gained attention as a cost-effective and environmentally friendly material due to its high adsorption capacity and potential for pollutant removal [2]. This study focuses on developing advanced biomaterials from agricultural waste, designed to selectively capture and degrade BPA through an integrated approach combining fixed bed column adsorption and biological treatment by solid state fermentation (SSF) using white rot fungi.

Vertical glass column with 3 cm inside diameter was used in the fixed-bed column experiments at room temperature. Continuous flow tests were performed using palm leaves biochar functionalized with clay (PLC5) for BPA removal. The experiment was conducted at different with a flow rate of 2 ml/min, with an inlet concentration BPA of 10 mg/L. Monitoring was performed until the biochar reached saturation. Breakthrough curves assays showed that saturation by BPA occurs at 2550 min with a 70% removal capacity. The saturated biochar underwent solid-state fermentation by the white rot fungus Ganoderma resinaceum, which has the ability to degrade complex molecules through its enzymatic pool. First, tolerance tests were conducted for a period of 9 days by tracking the fungal mycelium mat diameters in solid malt dextrose agar (MDA) media, at the micropollutants concentration range of 0.1 to 100 mg/L. BPA was found to be tolerated by the fungal strains up to the concentration of 100 mg/L with a tolerance index of 80%.

The SSF experiment was carried out in aerated batch flasks under controlled operating conditions (T°= 28°C, moisture content = 75 %). The enzymatic production of lignin peroxidase (LiP), manganese peroxidase (MnP), and laccase (Lac) was monitored throughout the process. The efficiency of fungi in BPA degradation was assessed, showing a significant increase in laccase activity correlating with BPA breakdown.

These findings highlight the potential of integrating fixed-bed column adsorption with solid-state fermentation as an effective remediation strategy. This process offers a sustainable and eco-friendly approach to address water scarcity while protecting groundwater resources from contamination.