Abstract
Anaerobic digestion of biomass has increasing implementation for bioenergy production. The solid by-product of this technology, i.e., the digestate, has relevant potential in agricultural and environmental applications. This study explored the capacity of a digestate from mixed feedstock to remove from water four endocrine-disrupting chemicals, namely the pesticides metribuzin (MET) and boscalid (BOS) and the xenoestrogens bisphenol A (BPA) and 4-tert-octylphenol (OP). The surface micromorphology and functional groups of the digestate were investigated using scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy, respectively. Results of sorption kinetics showed that all compounds reached the steady state in a few hours according to a pseudo-first-order model in the cases of MET and OP, a pseudo-second-order model for BOS and both models in the case of BPA. Data of adsorption isotherms were fitted to the Henry, Freundlich, Langmuir and Temkin equations. The adsorption of MET preferentially followed the non-linear Freundlich model, whereas the adsorption of the other compounds was properly described by both the linear and Freundlich models. The organic carbon partition coefficients, KOC, were 170, 1066, 256 and 2180 L kg−1 for MET, BOS, BPA and OP, respectively. The desorption of BOS, BPA and OP was slow and incomplete, indicating a phenomenon of hysteresis. In conclusion, the digestate showed a remarkable efficiency in the removal of the compounds, especially those with high hydrophobicity, thus behaving as a promising biosorbent for environmental remediation.
Highlights
The current practice of processing waste biomass to produce bioenergy is increasingly adopted all over the world, representing a virtuous alternative to the consumption of fossil fuels
Considering all this, the objective of this study was to investigate the quantitative aspects of the adsorption/desorption process of four endocrine-disrupting chemicals (EDCs) with contrasting physicochemical properties, namely MET, BOS, bisphenol A (BPA) and OP, on a DIG sample obtained from a mixed plant and animal biomass
The scanning electron microscopy (SEM) technique identifies the micromorphological aspects of the material surface with information on the distribution and allocation of the pores
Summary
The current practice of processing waste biomass to produce bioenergy is increasingly adopted all over the world, representing a virtuous alternative to the consumption of fossil fuels. Several traditional and innovative conversion technologies, such as pyrolysis, microgasification, hydrothermal carbonization and anaerobic digestion (AD), have been developed by scientists and specialists to obtain combustible biogas and biofuels from organic wastes or dedicated crops [1]. These processes can be combined to improve bioenergy production and usable remains [2,3]. These by-products can be exploited as biosorbents of various types of pollutants [4]
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