Evaluation of the reduction of methane emission in swine and bovine manure treated with black soldier fly larvae (Hermetia illucens L.).

The study evaluates Hermetia illucens larvae's ability to decrease direct methane emissions and nutrients from cattle and swine manure. Hermetia illucens larvae were put into fresh cattle and swine manure, and the same conditions, without larvae, for the control treatment were established. The methane emissions were measured until the first prepupae appeared. The methane emissions from the bioconversion of animal manure by Hermetia illucens larvae were up to 86% lower than in the control treatments (conventional storage). The cumulative methane emissions from cattle and swine manure bioconversion were 41.4 ± 10.5 mg CH4 kg-1 and 134.2 ± 17.3 mg CH4 kg-1, respectively. Moreover, Hermetia illucens larvae could reduce 32% of dry matter, 53% nitrogen, 14% phosphorus, and 42% carbon in swine manure. Meanwhile, in cattle manure, reductions of 17% of dry matter, 5% of nitrogen, 11% of phosphorus, and 15% of carbon and pH reductions in both swine and cattle manure were found. Thus, the production of larvae was higher in swine manure than cattle manure. Furthermore, the larvae frass from swine manure was appropriate for agricultural use, unlike the larvae frass from cattle manure requiring further processing. These results reveal the ability of Hermetia illucens larvae to mitigate methane emissions from animal manure and show it to be a promising technology for manure treatment, with great potential to promote a circular economy in the livestock sector.

Artificial neural network employment for element determination in Mugil cephalus by ICP OES in Pontal Bay, Brazil.

Fish are important sources of protein, making them very significant in the human diet. Although the consumption of this food is beneficial for health, it is essential that the product does not contain inorganic components above the limits recommended by the current legislation. Therefore, a method for determination of elements in fish (Mugil cephalus) samples was optimized. A simplex centroid mixture design with restriction was applied for optimization of the acid digestion of samples in an open system under reflux in order to evaluate the best ratio between the reagents HNO3, H2O2 and H2O. The results indicated that more intense analyte signals were obtained when a mixture containing 3.6 mL of HNO3 (65% v/v), 0.4 mL of H2O2 (30% v/v) and 6.0 mL of H2O was used. The accuracy of the method was assessed with a CRM of oyster tissue (NIST 1566b). The method presented relative standard deviations (RSDs) of 3.54%; 3.82%; 4.81% and 3.50% for Zn, Fe, Cu and S, respectively. The detection limits were 0.002 mg kg-1 for Cu and Zn and 0.02 mg kg-1 for Fe and S. The proposed method was applied for the determination of Zn, Fe, Cu and S in fish samples. A Kohonen Self-Organizing Map (KSOM) with K-means implementation was applied to better delimit the boundary between groups and the spatial and temporal influence on how concentrations of the chemical elements were perceived. To verify the separation, the Davies-Bouldin and Silhouette indices were used, obtaining 0.5374 and 0.8541, respectively, indicating satisfactory separation.

Removal of bromophenol blue anionic dye from water using a modified exuviae of Hermetia illucens larvae as biosorbent.

Organic dyes originating from liquid effluents from the textile industries are harmful to the environment. They are toxic and reduce the penetration of light into aquatic environments. In this study, a biosorbent was produced from the exuviae of Hermetia illucens (Linnaeus) larvae and used to remove organic anionic dyes from an aqueous medium. The solids were characterized in terms of thermal stability, chemical structure, morphology, and porosity using thermogravimetric (TGA), differential thermal analysis (DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and N2 adsorption-desorption. There were studied the effects of pH and dosage of the adsorbent on the adsorption of the bromophenol blue dye, used as a model molecule. The adsorption kinetics was studied with Lagergren's pseudo-first-order rate model. The maximum adsorbed amount was 571 mg g-1 according to Langmuir's model. The adsorption process was evaluated as exothermic and spontaneous and was classified as physical adsorption. The prepared biosorbent was tested in five consecutive adsorption cycles achieving 99% dye removal at each stage. This demonstrated the maintenance of adsorption efficiency and desorption capacity. These results suggest that prepared biosorbent have potential applications in the treatment of effluents from textile industries.

Assessment of autochthonous aquatic macrophytes with phytoremediation potential for dairy wastewater treatment in floating constructed wetlands.

The phytoremediation potential of autochthonous aquatic plants has been increasingly explored. This study investigated the use of macrophytes found in natural ecosystems in the southern coast of the state of Bahia, Brazil, for treatment of dairy wastewater (DWW) using experimental systems of the floating constructed wetland type. Four species of aquatic macrophytes have been tested using floating platforms made from PET bottles. The chemical oxygen demand (COD), biochemical oxygen demand (BOD), total solids (TS), pH, and temperature of DWW were analyzed for 15 days. On the fifth day, a 74.8% (±7.7) decrease of BOD was achieved. Eichhornia crassipes (86.4%) and Eichhornia paniculata (84.8%) showed the best results, while Polygonum ferrugineum and Borreria scabiosoides achieved the removal of 65% and 74.2% of BOD, respectively. Considering the TS reduction in the DWW diluted with rainwater, the best results were obtained by Eichhornia crassipes (64.3%) and Eichhornia paniculata (65.18%). The macrophytes of the Eichhornia genus showed a greater potential for the treatment of DWW than the macrophytes Polygonum ferrugineum and Borreria scabiosoides, with a hydraulic retention time varying between four and five days.

Antimicrobial activity of coconut oil-in-water emulsion on Staphylococcus epidermidis and Escherichia coli EPEC associated to Candida kefyr.

Candida kefyr has been considered both a food-spoiling agent and a type of yeast with fermentation properties. In this study, the authors have evaluated the antimicrobial activity of a coconut oil-in-water emulsion associated to the presence of C. kefyr. Fresh coconut kernels were used to obtain the coconut oil-in-water emulsion, the sterile coconut oil-in-water emulsion by decantation, and the coconut oil by means of a heating process. Commercial virgin coconut oil was also used. Agar diffusion, minimal inhibitory concentration and minimal bactericidal concentration (MIC/MBC) techniques were employed to evaluate antimicrobial activity against E. coli and S. epidermidis. The C. kefyr isolate was identified and confirmed. Coconut milk-derived fatty acids were characterized by acid index and thin layer chromatography. Scanning electronic microscopy was performed to evaluate the morphology of the microorganisms. Lipase activity of C. kefyr isolate was also detected. Coconut oil-in-water emulsion associated to C. kefyr was active against both bacteria. Thin layer chromatography confirmed the presence of triglycerides and free fatty acids. The acid index showed higher acidity potential for the coconut oil-in-water emulsion. The microscopic images showed antibacterial action through the formation of membrane holes' and demonstrated yeast shape. All the above show new potentials for C. kefyr and coconut oil-in-water emulsion in food technology.