Dairy industry wastewater contains high levels of organic matter, consisting mainly of fat, protein and products of their partial microbial decomposition. In the present study, the use of continuous electrocoagulation is proposed for the primary treatment of dairy wastewater. The electrochemical treatment was carried out in a continuous flow cell with aluminum electrodes. The influence of the voltage, the distance between the electrodes and the hydraulic residence time (HRT) on the process performance was assessed, by measuring the removal of color, turbidity, total organic carbon (TOC) and chemical oxygen demand (COD). The optimum voltage, distance between the electrodes and HRT were 10 V, 1 cm and 90 min, respectively, yielding a current density of 13.3 A.m − ². Under these conditions, removal of color, turbidity, TOC and COD were 94%, 93%, 65% and 69%, respectively, after a steady state was reached in the continuous flow reactor.

This study evaluates the feasibility of nitrogen recovery from wastewater via electrochemical methods as an alternative nutrient source for agricultural applications. Ammonium nitrogen (NH₄⁺-N) and phosphate (PO₄³⁻-P) contamination poses significant environmental risks and challenges water resource management globally. The electrochemical precipitation of struvite (MgNH₄PO₄·6H₂O) offers a promising solution for nutrient recovery, with potential applications as a slow-release fertilizer. Experimental results demonstrate that increased current density (from 2.5 to 7.5 mA/cm²) and reduced electrode distance (1 cm) significantly enhance NH₄⁺ and PO₄³⁻ consumption and struvite precipitation. Increasing the amperage from 2.5 to 7.5 mA·cm⁻² at a 1 cm electrode distance raised the ammoniacal nitrogen incorporation from 1.59 to 5.34 g/100 g, signifying greater struvite production. The Mg and P concentrations were 15.44 and 12.60 g/100 g, respectively, for this higher amperage, although lower than the concentrations seen with 2.5 mA·cm⁻² (22.16 and 14.52 g/100 g). The majority of Mg (60%) and P (93.6%) were, however, incorporated within struvite. Additionally, this study reveals that Mg is primarily incorporated as struvite when using higher current densities, while lower current densities yield greater Mg incorporation in non-struvite forms, such as magnesium carbonate. Findings suggest that optimizing current density and electrode distance can improve nitrogen and phosphorus recovery efficiencies, making electrochemical struvite production a viable, sustainable approach for nutrient recycling. This method not only reduces dependence on synthetic fertilizers but also supports sustainable agricultural practices by transforming wastewater contaminants into valuable resources.

Phosphorus in agriculture is an essential, limited, and strategic resource, and its sustainable management is a global challenge. Phosphorus (P) recovery as struvite (NH ₄ MgPO ₄ .6H ₂ O) from manures and municipal and agro-industrial wastewaters has been considered one of the most sustainable technologies, based on the circular economy, to face challenges regarding P reserves and its use for conventional fertilizer production. Struvite is a slow-release P-fertilizer (5 % N, 12 % P, 10 % Mg), which could significantly reduce the Brazilian dependency on fertilizer imports. We found a large number of recent studies that show its predominant application for temperate and Mediterranean regions. However, its potential as a fertilizer and better use for subtropical and tropical regions, such as Brazilian agriculture, is still unknown. We highlight that: (i) crop responses reported were quite variable with few field studies carried out; (ii) the crop yield expected may be on average 10 % below those in soluble P sources; (iii) a potentially high residual effect should be effectively measured; (iv) promising use of struvite mixed with soluble P-fertilizers to produce high yields; (v) higher efficiency than manure, composts or phosphate powder rocks. In fact, there is a lack of studies carried out on subtropical and tropical soils and climates; none were found in Brazil. Therefore, the lack of studies on Brazilian soils is a barrier to a precise evaluation of struvite as a fertilizer for Brazil’s agricultural systems, especially for acidic Oxisols and no-till systems. Finally, struvite production from swine wastewater can expand in specific states in the South, Southeast, and Midwest of Brazil, where the swine production is concentrated. S truvite production technology might be easily adopted and affordable for medium- to large-scale confined swine operations, which could yield some 300,000 Mg of struvite per year.

This study explored the use of chicken feathers, a low-cost and abundant agricultural byproduct, as a sorbent for the removal of reactive yellow dye from aqueous solutions. The dual potential of feathers as both adsorbents and sorbents, attributed to their keratin-rich structure, was utilized to investigate their effectiveness in dye removal. Feathers, activated with 1.0 mol/L HCl, exhibited a maximum adsorption capacity at 70 °C and pH 5.5, as determined from Langmuir isotherm modeling. A 2² central composite rotatable design revealed that temperature and pH significantly influence the adsorption efficiency, with higher temperatures favoring the process. Kinetic studies demonstrated pseudo-first-order behavior, with rapid initial adsorption reaching equilibrium within 120 min. Thermodynamic analysis confirmed the endothermic nature of the process (ΔH° = 28.04 kJ mol⁻¹), a positive entropy change (ΔS° = 66.62 J/mol·K), and a reduction in Gibbs free energy (ΔG°) with increasing temperature, suggesting enhanced feasibility at elevated temperatures. This research highlights the potential of utilizing poultry industry residues as sustainable and efficient sorbents for environmental remediation, contributing to waste valorization and eco-friendly wastewater treatment solutions.

Sweeteners are food additives consumed worldwide, especially by individuals with restrictive diets. This study evaluated the cytotoxic and genotoxic effects of sweeteners widely sold in Brazil through a bioassay with Allium cepa. Onion bulbs were exposed to different concentrations of sweeteners, and their root cells were stained with acetic carmine and analyzed under an optical microscope. Distilled water was used as a negative control, and glyphosate as a positive control. The results demonstrated that the mitotic index (MI) and the chromosome aberration index (CAI) of the three sweeteners tested did not differ significantly from the negative control, indicating that they are not toxic or mutagenic additives. This result is positive for consumers of these products, especially those who need to replace sugar due to dietary restrictions. However, they should be consumed with caution.