Low nutrient and high pH of circulating water represent two of the main issues to overcome for a successful combination of aquaculture and hydroponics in aquaponics offering a sustainable and circular economy solution for vegetable production. The purpose of this study was to screen the tolerance of four herbs to high pH and low nutrient concentration in hydroponics, i.e., green and red basils, mint, and rocket salad, with a focus on plant yield and nutraceutical aspects. Results highlighted green basil as the most tolerant species to low nutrient and high pH conditions followed by mint. On the contrary, negative effects from high pH and low nutrient were reported on red basil and especially rocket salad, which strongly affect their marketability parameters. Rocket salad fresh biomass was more than halved under the combination of high pH and low nutrients. Results on green and red basil showed the importance of testing the tolerance to these agronomic conditions at both species and variety levels. Despite the reduction in biomass, leaf pigments were not influenced by high pH and low nutrients and therefore can be considered parameters of minor importance for the evaluation of these species. In conclusion, the tolerance of green basil and mint to high pH and low nutrients under hydroponic conditions has been highlighted. Further investigation coupled with fish farming will be able to reinforce the convenience of using these species for aquaponics.

This paper reports a novel eco-friendly one-step synthesis of maltodextrin-based cationic polymers developed exploiting amine-mediated ring-opening reactions of water-soluble diglycidyl ethers.

Anaerobic digestion is one of the most important and advantageous processes in livestock manure treatment. Digestate, one of its byproducts, contains particularly high nitrogen levels that determine storage and disposal costs. Excess nitrogen can be managed through sequestration processes. This study assesses the potential of natural zeolite to adsorb ammonium ions from a simulated ammonium-rich digestate, and to verify its absorbency and efficiency to release fertilizer slowly to strawberry plants. The assessment considered the effects on the plant, fruit quality, prokaryotic abundances and relative abundance of bacterial and archaeal functional genes related to nitrification. Our results confirm that ammonium-enriched zeolites possess positive implications for strawberry plants and favorably influence bacterial nitrification. Natural zeolites demonstrated high sorption properties and were shown to be an efficient carrier of N to plants.

Water kefir is an acid, softly alcoholic and fragrant beverage fermented by a stable consortium of multispecies microbial community. Aim of this study was to investigate the ability of water kefir grains to abate significant amounts of heavy metal ions during the preparation of the water kefir beverage and to set up an experimental and analytical methodology based on ICP-OES spectroscopy and ionic chromatography for the evaluation of heavy metal bioaccumulation by water kefir grains. We investigated the absorption kinetics of the process. The use of EPR spectroscopy enabled us to characterize the interaction between water kefir grains and paramagnetic metal ions from the structural viewpoint. Our results highlight significant differences in both the kinetics and the structural aspects of the interaction between distinct metal ions and water kefir grains. They concur clarifying the potential role of water kefir grains as detoxifying agents towards heavy metal ions. Graphical Abstract