Sand washing of oil spill-affected beaches using concentrated ß-glucans obtained from residual baker's yeast.

Valorization of residual yeast of the bakery industry for use in the remediation of oil-contaminated soils as an emulsifier is a biocompatible and effective process that will reduce environmental pollution. The aim of this study was to use concentrated ß-glucan obtained from residual baker's yeast, Saccharomyces cerevisiae, as an emulsifier to remove total petroleum hydrocarbons (TPH) from the contaminated sands of two beaches affected by the oil spill that occurred in January 2022 north of Lima, Peru. The extraction and concentration of ß-glucan from sand were performed at a pilot scale using autolysis with 3 % sodium chloride, temperature elevation, treatment with organic solvents and water, hydrolysis via proteases, and vacuum filtration. The chemical composition and functional properties of concentrated ß-glucan were evaluated to determine its quality and efficacy. In addition, the values of TPH removal efficiency obtained using concentrated ß-glucan, water, and the commercial emulsifier Tween-80 were compared. The mass recovery of concentrated ß-glucan was 5.59 %, with a ß-glucan content of 38.60 %. The efficiency of ex-situ removal of TPH from hydrocarbon-impacted sands containing 78323 mg/kg of TPH reached 50 % and 70 % when the concentrated ß-glucan concentrations used were 70.3 % and 80.3 %, respectively. These efficiency values are higher than those obtained when water was used for TPH removal but lower than those obtained when Tween-80 was used for TPH removal.

Stabilization of residual mercury from gold mining as metacinnabar and cinnabar in ball mills on a pilot scale.

Waste liquid mercury generated as a by-product of the Merrill-Crowe process in gold mining and recovered from mercury-containing waste must be stabilized for secure storage or disposal. This study developed a procedure for mercury stabilization. A ball mill with a 0.5 m3 capacity and a rotational speed of 43 rpm was used to stabilize the residual mercury with sulfur. The treatments were conducted for 30, 60, and 90 min at mercury: sulfur molar ratios of 1.0, 0.8, and 0.67. The ball loading ratio was 7.0 with residual mercury, and the temperature was below 40 °C. The treatment efficiency was evaluated by measuring the concentrations of mercury and other metals using the Toxicity Characteristic Leaching Procedure (TCLP), examining the stabilized residual mercury by X-ray diffraction, and conducting bioassays on Daphnia magna and Lactuca sativa. Principal component analysis (PCA) was performed on the aforementioned variables. The 90-min treatment, with a mercury-to-sulfur molar ratio of 0.67, stabilized mercury mainly as cinnabar compared with the other treatments and presented leachate mercury values below the detection limit <0.003. The leachate from the treatments also showed values of 21.28-38.44 toxic units, classified as very toxic, and generated toxicity, particularly for D. magna, because of the presence of other metals such as Al, Ba, B, Ca, Cu, Cr, Fe, Mn, Ni, and Zn. The variability of the residues in the PCA analysis was explained by the treatment effect and the presence of other metals in the residual mercury. The stabilized residual mercury obtained was classified as non-hazardous and could be stored or disposed of as ordinary waste in a security landfill.

The predictive model of hydrobiological diversity in the Asana-Tumilaca basin, Peru based on water physicochemical parameters and sediment metal content.

The hydrobiological diversity in the basin depends on biotic and abiotic factors. A predictive model of hydrobiological diversity for periphyton and macrobenthos was developed through multiple linear regression analysis (MLRA) based on the physicochemical parameters of water (PPW) and metal content in sediments (MCS) from eight monitoring stations in the Asana-Tumilaca Basin during the dry and wet seasons. The electrical conductivity presented values between 47.9 and 3617 µS/cm, showing the highest value in the Capillune River due to the influence of geothermal waters. According to Piper's diagram, the water in the basin had a composition of calcium sulfate and calcium bicarbonate-sulfate. According to the Wilcox diagram, the water was found to be between good and very good quality, except for in the Capillune River. The Shannon-Wiener diversity indices (H') were 2.62 and 2.88 for periphyton, and 2.10 and 2.44 for macrobenthos, indicating moderate diversity; for the Pielou's evenness index (J'), they were 0.68 and 0.70 for periphyton, and 0.68 and 0.59 for macrobenthos, indicating similar equity, in the dry and wet seasons, respectively, for both indices. In the model there were three cases, where the first two cases only worked with PPW or MCS, and case 3 worked with PPW and MCS. For case 3, the predicted values for H' and J' of periphyton and macrobenthos concerning those observed presented correlation coefficients of 0.7437 and 0.6523 for periphyton and 0.9321 and 0.8570 for macrobenthos, respectively, which were better than those of cases 1 and 2. In addition, principal component analysis revealed that the As, Pb, and Zn contents in the sediments negatively influenced the diversity, uniformity, and richness of the macrobenthos. In contrast, Cu and Cr had positive impacts because of the adaptation processes.

Valorisation of Zingiber officinale Roscoe postharvest residues as byproducts with antioxidant capacity.

During the postharvest phase of ginger, 2.6%-5% by weight of ginger rhizome residues are generated, which are disposed in landfills and constitute a continuous source of organic contamination causing serious environmental problems. The objective of this study was to valorise ginger postharvest residues (shoot, finger, slice, trunk, root, and rootles) from district Pichanaki (Peru) as dry powdered byproducts with an antioxidant capacity similar to that of rhizome. The nutrition composition, phenolic compounds, such as total phenolic content, total flavonoid content, 6-gingerol content, and 6-shogaol content, antioxidant capacity expressed by ferric reducing antioxidant power and IC50 of 2,2-diphenyl-1-picrylhydrazyl radical, surface changes, and structural morphology were evaluated. In addition, the dependent variables were correlated using the Pearson's matrix and principal component analysis (PCA). The results for shoot, finger, slice, and trunk residues showed similar phenolic compound contents and antioxidant capacities to those of rhizome, but similar results were not obtained for root and rootlet residues. These results were corroborated by analyses of surface and structural morphologies. The Pearson's matrix showed that the content of phenolic compounds correlated with the antioxidant capacity and carbohydrate content for the rhizome and residues, except for the root. The PCAshowed that residues that exhibited higher contents of starch grains with reserve functions such as shoot, finger, slice, and trunk were correlated with higher contents of phenolic compounds with antioxidant capacity, while residues with higher contents of crude fibre and ash with a support function exhibited a low antioxidant capacity. Thus, the shoot, finger, slice, and trunk residues, from district Pichanaki (Peru), can be valorised and reincorporated as byproducts in the ginger value chain. They are important for the food, cosmetic, and pharmaceutical industries.

Evaluation of antioxidant capacity, structure, and surface morphology of ginger (Zingiber officinale) using different extraction methods.

The antioxidant capacity of ginger depends on the type of variety, growing conditions, postharvest, drying method, extraction, and measurement, among others. The objective of the research was to compare the efficiency of ultrasound (US), magnetic agitation (AM), maceration (M), and reflux (R) extraction methods. In the GFD (fresh air-dried ginger) extract, the contents of total phenolic content (TFC), 6-gingerol (6-G), and 6-shogaol (6-S) were evaluated; as well as the antioxidant capacity by FRAP (ferric reducing antioxidant power) and IC50 in DPPH (2,2-diphenyl-1-picrylhydrazyl radical). In addition, structural and morphological changes were evaluated with FTIR and SEM, respectively. The results for all extraction methods for TFC, 6-G, and 6-S were between 9.422 and 10.037 mg EAG/g dry matter (dm), 4.072-4.838, and 0.194-0.263 mg/g dm respectively, with the highest values for TFC and 6-G for M and 6-S for R. FRAP and IC50 in DPPH values were between 0.172 and 0.192 mmol Fe2+/g dm and 0.531-0.722 mg dm/mL respectively, presenting higher antioxidant capacity in M and R1, R2, and R3 (1, 2, and 5 h, respectively). Extracts from M and R1 methods presented lower FTIR transmittance values and greater changes in their surface morphology, with folds and breaks in the starch granules by SEM images. It is concluded that extracts with higher antioxidant capacity are obtained using medium polarity solvents such as methanol and with M and R1 methods. Because of the longer extraction time and moderate thermal stress, the structure and surface morphology of the extracted GFD sample showed greater changes on the surface of the starch granules and, consequently, greater extraction of bioactive compounds.