Valorization of agricultural olive waste as an activated carbon adsorbent for the remediation of water sources contaminated with pharmaceuticals

The present study investigates the performance of activated carbon from olive pomace (ACOP) in the removal of hydrophilic organic pharmaceutical micropollutants such as the antibiotic sulfamethoxazole (SMX) from water. The adsorption behavior of two chemically modified ACOP was investigated considering their interesting textural properties, relevant surface functions and charges. The performances in terms of adsorption capacity were investigated and optimized with respect to the main operating conditions. Comparison of SMX adsorption capacities on ACOP with commercial powdered activated carbon and nanoporous carbonaceous materials prepared from argan shells revealed that ACOP enabled the highest adsorption capacities (39.68 mg g−1). The adsorption behavior was attributed not only to the textural properties, such as the large surface area (1857 m2 g−1) and porosity, but also to the charge and functional groups of the surface

Hydrothermal carbonization vs. anaerobic digestion to valorize fruit and vegetable waste: A comparative technical and energy assessment

Herein, the valorization of vegetable and fruit waste was assessed via hydrothermal carbonization (HTC) and anaerobic digestion (AD) in terms of product characterization and energy requirements. HTC was conducted at reaction temperatures between 150 ºC and 190 ºC, and residence times between 20 min and 40 min. The increase in the process severity resulted in hydrochars with higher carbon contents and higher energy densification ratios. AD was performed in two different ways. i.e., batch and semi-continuous reactions. From the batch experiments a methane yield of 300 L CH4/kg VS was obtained, while for the semi-continuous, the average specific methane production estimated (for HRTs from 75 to 50 days) was 213 ± 32 L CH4/kg VS. To estimate the energy requirements, mass and energy balances were performed considering the basic stages of each process to obtain a suitable biofuel material. In this sense, it was concluded that for this specific waste, AD was a more suitable process with a positive energy net balance. On the contrary, HTC presented a negative energy net balance being required 1.29 MJ/kg of fresh food waste. A combined HTC-AD treatment may be an efficient method to take advantage of both technologies leading to higher energy efficiencies and other valuable products.Khadija Metyouy would like to thank the University of León for her scholarship (within the framework of Erasmus). This work has been partially supported by the grant FJC2021-047672-I, co-financed by MCIN/AEI/10.13039/501100011033 and the European Union NextGenerationEU/PRTR Funds. A big thank you to all the team of the Grupo Ingeniería Química, Ambiental y Bioprocesos (IQUIMAB) Universidad de León and especially for Marta E. Sánchez and Jorge Cara-Jiménez for sharing information and knowledge from their experiences.Peer reviewe