Investigating the Evolution of Structural Characteristics of Humic Acid Generated during the Continuous Anaerobic Digestion and Its Potential for Chromium Adsorption and Reduction

Humic acid (HA), as an important by-product, has been demonstrated to affect anaerobic digestion performance and subsequent land application of digestate via the batch process. However, knowledge about evolution structure function HA during continuous (AD) is still unclear. Therefore, current study examined structural changes in produced AD process its metal-adsorption-reduction abilities. The results three-dimensional fluorescence spectroscopy showed a general upsurge humic-like components’ abundance (70–77%), with increase humification index (2.56–3.43). Likewise, content increased from 4.8 g L?1 6.9 C-H, O-H, C=O, C=C, C-O functional groups was observed 2D COS FTIR analysis. Moreover, concurrent dynamics contributed higher adsorption (255.2 mg g?1) Cr (VI) reduction (60.3 (III) after 168 days findings not only advanced understanding metal remediation potential but also support further research toward developing eco-friendly innovative strategy for heavy metals contaminated soils employing auxiliary agent.