Adsorption enhanced biological treatment of hydrothermal liquefaction aqueous phase derived from municipal sludge.

Hydrothermal liquefaction (HTL) is a promising method for municipal sludge valorization through waste minimization and biofuel production. The process wastewater, HTL aqueous, presents a significant challenge for scale-up due to recalcitrant compounds. In this study, granular activated carbon (GAC) was used to remove potential inhibitors from HTL aqueous through adsorption to enhance aerobic and anaerobic biological treatment. GAC removed up to 61 % chemical oxygen demand (COD), 50 % biochemical oxygen demand (BOD) and potential inhibitors, such as total phenolic compounds (87 %) and N-heterocycles (90 % of pyridines) at 100 g/L. Conversely, most volatile fatty acids remained in HTL aqueous. Subsequently, mesophilic and thermophilic specific methane potential increased by up to 97 % and 83 %, respectively. BOD increased by up to 50 %, which enhanced BOD/COD ratio from 81 % to 93 % before and after adsorption. This study established the groundwork for HTL aqueous adsorption, described mechanism for pollutant removal, and provided insights for biological treatment.

In vivo assessment of the toxic impact of exposure to magnetic iron oxide nanoparticles (IONPs) using Drosophila melanogaster.

Iron oxide nanoparticles (IONPs) have useful properties, such as strong magnetism and compatibility with living organisms which is preferable for medical applications such as drug delivery and imaging. However, increasing use of these materials, especially in medicine, has raised concerns regarding potential risks to human health. In this study, IONPs were coated with silicon dioxide (SiO2), citric acid (CA), and polyethylenimine (PEI) to enhance their dispersion and biocompatibility. Both coated and uncoated IONPs were assessed for genotoxic effects on Drosophila melanogaster. Results showed that uncoated IONPs induced genotoxic effects, including mutations and recombinations, while the coated IONPs demonstrated reduced or negligible genotoxicity. Additionally, bioinformatic analyses highlighted potential implications of induced recombination in various cancer types, underscoring the importance of understanding nanoparticle-induced genomic instability. This study highlights the importance of nanoparticle coatings in reducing potential genotoxic effects and emphasizes the necessity for comprehensive toxicity assessments in nanomaterial research.

Treatment of aqueous phase from hydrothermal liquefaction of municipal sludge by adsorption: Comparison of biochar, hydrochar, and granular activated carbon.

Hydrothermal liquefaction (HTL) is promising for treating waste with high moisture, such as municipal sludge, and producing biocrude (a petroleum-like biofuel). However, a large amount of wastewater byproduct, HTL aqueous, is generated. The presence of hazardous compounds (e.g., phenolic compounds and nitrogenous organics) makes HTL aqueous the biggest bottleneck for full-scale implementation at treatment plants. This study investigated the adsorption of various pollutants, focusing on chemical oxygen demand (COD), in HTL aqueous to granular activated carbon (GAC), biochar, and hydrochar. It assessed the effect of pH, temperature, time, and adsorbent concentration on adsorption efficiency and identified proper adsorbent and process conditions for removing most of the pollutants from HTL aqueous. GAC showed the highest adsorption capacity (184 mg/g) for COD, surpassing biochar (44 mg/g) and hydrochar (42 mg/g). The adsorption of COD to all adsorbents followed pseudo-second-order kinetic and Freundlich isotherm, suggesting that the adsorption of HTL aqueous pollutants is a heterogeneous and multilayer process, limited by chemosorption. The adsorption was endothermic, favored by elevated temperatures and neutral pH. This means adsorption is more efficient and economical for treating HTL aqueous that is a hot stream at the large-scale and it saves chemical needs. Lastly, GAC was highly efficient and selective in removing harmful pollutants, such as COD (up to 66%), total phenolic compounds (up to 94%), pyrazines (up to 99%), pyridines (up to 100%), and cyclic ketones (up to 95%) while preserving valuable volatile fatty acids (VFAs) and ammonia for subsequent recovery. Removal of potentially inhibitory compounds and preserving VFAs are crucial for carbon recovery in anaerobic biological treatment of HTL aqueous. The results suggested the necessity of optimizing adsorbent dose for maximizing removal of specific group of inhibitory compounds in full-strength HTL aqueous for enhancing downstream biological treatment. Lastly, this study established the groundwork for HTL aqueous adsorption, elucidating its effectiveness and mechanism for pollutant removal.