Residual biomass from agri-food production chain and forestry are available in huge amounts for further valorisation processes. Delignification is usually the crucial step in the production of biofuels by fermentation as well as in the conversion of cellulose into high added-value compounds. High-intensity ultrasound (US) and hydrodynamic cavitation (HC) have been widely exploited as effective pretreatment techniques for biomass conversion and in particular for cellulose recovery. Due to their peculiar mechanisms, cavitational treatments promote an effective lignocellulosic matrix dismantling with delignification at low temperature (35–50 °C). Cavitation also promotes cellulose decrystallization due to a partial depolymerization. The aim of this review is to highlight recent advances in US and HC-assisted delignification and further cellulose recovery and valorisation.

Lignin is a fascinating aromatic biopolymer with high valorization potentiality. Besides its extensive value in the biorefinery context, as a renewable source of aromatics lignin is currently under evaluation for its huge potential in biomedical applications. Besides the specific antioxidant and antimicrobial activities of lignin, that depend on its source and isolation procedure, remarkable progress has been made, over the last five years, in the isolation, functionalization and modification of lignin and lignin-derived compounds to use as carriers for biologically active substances. The aim of this review is to summarize the current state of the art in the field of lignin-based carrier systems, highlighting the most important results. Furthermore, the possibilities and constraints related to the physico–chemical properties of the lignin source will be reviewed herein as well as the modifications and processing required to make lignin suitable for the loading and release of active compounds.

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Tetracyclines are widely used antibiotics that are often carelessly released into the environment, posing a potential threat to the ecosystem. Due to the lack of efficient methods to remove tetracyclines from wastewater, a remarkable research effort on the remediation of tetracyclines has been undertaken. The synergistic effect of hydrodynamic cavitation (HC) and electrical discharge (ED) plasma on the degradation of a number of antibiotics in water has been studied in this work. Catalyst- and oxidant-free processes have been carried out using a new pilot-scale hybrid device (HC/ED plasma) working in flow-through mode (330 L/h). Tetracycline hydrochloride (TC), doxycycline hyclate (DC) and oxytetracycline dihydrate (OC) were selected as the model compounds. Antibiotic degradation tests were performed using a 5 L water solution at various antibiotic concentrations (10, 25, 50, 75, and 100 mg/L). All experiments were performed over 15 min, and samples were either collected using the flow-through method, or every 5 min when using the loop configuration. The temperature was kept constant at 30 °C, with fluctuations of ±2 °C. The influence of applied HC input pressure (45, 60, and 70 bar), applied ED amplitude frequency (10 and 48 kHz) and the pH values of the initial solutions (2 and 11) on antibiotic degradation rate have been investigated. Near quantitative TC (>98%), DC (98%) and OC (95%) degradation was documented after only 15 min of combined HC/ED plasma treatment at 70 bar and 48 kHz. To better understand the synergistic effect of coupled HC/ED treatment on antibiotic degradation, a dosimetry assay was performed to quantify the oxidizing compounds generated by this technology. Specifically, the coupled HC/ED plasma treatment was able to linearly increase the amount of oxidants in water as a function of time, reaching a maximum concentration of 13.426 mmol/L after 15 min, which is more than 85-times higher than that of HC alone (0.153 mmol/L). This study demonstrates the impressive efficiency of hybrid HC/ED plasma technology in degrading recalcitrant antibiotics in wastewater without the need for catalysts and oxidants.

The biologically-derived polymers polyhydroxyalkanoates (PHAs) are biodegradable and can be considered a valuable alternative to conventional fossil-based plastics. However, upstream and downstream processes for PHA production are characterized by high energy and chemical consumption and are not economically competitive with petroleum-based polymers. Aiming to improve both the environmental and economical sustainability of PHAs production, in this work, corn straw was used as raw material to obtain a mixture of fermentable sugars after microwave-assisted flash hydrolysis (2 min, 0.01 g/L, 50.7% yield). A mixed microbial culture enriched from dairy industry waste was used for fermentation in a shake flask, allowing us to achieve good poly(hydroxy-butyrate-co-hydroxy-valerate) yields (41.4%, after 72 h of fermentation). A scale-up in a stirred tank bioreactor (3 L) gave higher yields (76.3%, after 96 h), allowing in both cases to achieve a concentration of 0.42 g/L in the fermentation medium. The possibility of producing PHAs from agricultural waste using a mixed microbial culture from the food industry with enabling technologies could make the production of biopolymers more competitive.