The global population faces increasing challenges in securing fresh water and food production. Aquaculture, a key source for obtaining protein, contributes significantly to environmental pollution, releasing suspended solids, organic matter, nitrogen, and phosphorus into water bodies. Some wastewater treatment methods can be expensive due to high equipment, energy, reagents, and maintenance costs, prompting the search for more sustainable alternatives. This study evaluates the performance of tannin-based coagulants from Castanea sativa shells (CS) for treating the recirculating water in an aquaculture plant. Two tannin-based coagulants, C1 and C2, were produced using ethanolamine (ETA) and NH₄Cl, respectively. The efficiency in removing color, turbidity, organic matter, nitrogen, and phosphorus was compared to a commercial tannin-based coagulant (Tanfloc SG) and chemical ones (FeCl₃ and Al₂(SO₄)₃). Coagulant C2, at 10 mg L^-1, removed 90 % of turbidity and 32 % of phosphorus, outperforming the Al-based coagulants (20 mg L^-1). Moreover, CS-based coagulants reduced natural organic matter (NOM), expressed as UV absorbance at 254 nm, and dissolved organic carbon (DOC), though none significantly reduced the nitrogen levels. Toxicity tests indicated low bacterial inhibition, with C1 and C2 showing inhibition rates of 8-10 %. The sludge produced was rich in calcium (97-1500 mg g^-1), magnesium (408-638 mg g^-1), and potassium (347-894 mg g^-1), making it suitable as a soil conditioner, though further research is necessary. Tannin-based coagulants, particularly from chestnut shells, offer a promising, sustainable solution for the post-treatment of the effluent from an aquaponics system on a fish farm while reducing organic sludge production.

The agricultural sector faces significant challenges related to climate change and population growth, which intensify pressure on natural resources and food security. Sustainable resource-efficient systems, alongside wastewater valorisation, are a promising solution. This study evaluated the reuse potential of aquaculture, urban, and swine farm wastewater in hydroponic cultivation. Trials with leafy vegetables and fruit crops were conducted in aquaponic systems containing two fish species (Koi carp and African catfish) and two small-scale hydroponic systems. Water quality, plant development, and environmental parameters were monitored. Results for the best performance scenarios within each cultivation system showed that in urban wastewater, strawberries yielded 183 ± 74 g/plant, exceeding yields in aquaponics (125 ± 60 g/plant). Lettuce performed better in swine farm wastewater (180 ± 39 g/plant) than in urban (65 ± 6 g/plant), with corresponding water-use efficiencies of 117 and 65 g/L. Aquaponics also supported stable yields, up to 108 ± 1 g/plant for lamb’s lettuce and 10,047 ± 8791 g of papaya fruit per plant. Nutrient recovery in hydroponic systems supplied with urban and swine farm wastewater reached up to 95% for N, P, and K. Overall, these systems demonstrated substantially lower water consumption compared with values commonly reported for conventional agriculture, underscoring their strong sustainability advantages.

Introduction/Materials: Modern agriculture faces the challenge of balancing high crop yields with sustainable resource management and nutritional quality. Here, soil and soilless systems (hydroponics and aquaponics) for cultivating the day‐neutral cultivar ‘Albion’ of the garden strawberry ( Fragaria × ananassa Duch.) were compared in terms of fruit quality and production yields. Methods/Results: Physicochemical parameters, including total soluble solids (TSS), reducing sugars, crude protein, ash, moisture, pH, minerals, total phenolic content (TPC), antioxidant capacity (AC), and pigment levels (anthocyanins, chlorophylls, carotenoids, and CIE Lab colour measurements) were used to assess fruit quality. Soil cultivation achieved the highest biomass and mineral content (ash, K, and Mg), suggesting superior plant adaptation. Hydroponics yielded the heaviest fruits (~ 16 g) with more reducing sugars (860.1 mg.g ⁻¹ dw) and TSS (8.77 °Brix), also leading to the highest cell viability. Conversely, despite having the lowest yields, aquaponically grown fruits were the richest in health‐promoting compounds, exhibiting the highest AC (46.8 mg VCEAC.g ⁻¹ dw), TPC (32.7 ± 4.2 mg GAE.g ⁻¹ dw), and anthocyanin content (261.9 ± 13.1 mg.L ⁻¹ dw). All systems produced fruits with low microbial loads and no toxic effects to FL8‐3B liver cells. Conclusion: Soil cultivation has a low energy impact but leads to lower levels of marketable fruits and is less efficient in water and nutrient management. Substrate hydroponics provides strong control over production parameters and uses synthetic nutrients that can be precisely tailored to crop demands, while aquaponics systems although having higher operational complexity and leading to lower crop yields, are highly efficient in water and nutrients and produce fruits of higher nutritional quality.