This study evaluates the concentration of PM10 and PM2.5 and identification of source in the districts of San Juan de Lurigancho and Puente Piedra (PPD) in Lima-Peru. The samples were collected from April to May 2017 by the National Meteorology and Hydrology Service of Peru (Senamhi). The concentration of PM10 and PM2.5, measured by gravimetric techniques, exceeded the international (WHO) and national standards; with maximum values for PM10 and PM2.5 of 160 and 121.56 µg/ m3 in PPD and 295.06 and 154.58 µg/ m3 in SJL. Identification of sources by the Positive Matrix Factorization Model (PMF 5.0) and Principal Component Analysis (ACP), showed similar sources for both districts. In SJL, the combination of vehicular traffic and resuspension of soil dust, marine aerosol and iron and steel industry was determined, while in PPD the resuspension of soil dust, vehicular source, industrial activity and marine aerosol.
Microbial biomass is considered a renewable and environmentally friendly resource. Thus, the research conducted a kinetic study and thermodynamic equilibrium modeling of the cobalt (Co) and manganese (Mn) bioadsorption process using the Rhodococcus opacus (RO) strain as a biosorbent. The inactive biomass subjected to 0.1 M NaOH pretreatment was brought into contact with synthetic solutions of Co and Mn. The experimental data for the Co(II) and Mn(II) bioadsorption process were fit to the Langmuir model with kads of 0.65 and 0.11 L.mg -1 , respectively. A better statistical fit was also obtained for the pseudo-second order kinetic model (R 2 Co(II) = 0.994 and R 2 Mn(II) = 0.995), with 72.3% Co(II) and 80% Mn(II) removals during the first 10 min. In addition, a higher affinity of RO for the Co(II) ion was observed, with maximum uptake values of 13.42 mg.g -1 ; however, a higher adsorption rate was observed for Mn(II) ion (k = 0.21 g.mg -1 .min -1 at 318 K). The bioadsorption process was spontaneous and dependent on temperature, being endothermic and irreversible for the Co(II) ion (∆H = 2951.91 J.mol -1 ) and exothermic and reversible for the Mn(II) ion (∆H = -2974.8 J.mol -1 ). The kinetic and thermodynamic equilibrium modeling allowed to identify the main mechanisms involved in the biosorption process of both metals. of time and temperature on the biadsorption process was studied, and the experimental data were evaluated using the pseudo-first order and pseudo-second order kinetic models, as well as the Langmuir and Freundlich isotherms.
The present study evaluated the application of 6 fungal microorganisms in the degradation of high-density polyethylene (HDPE) and low-density polyethylene (LDPE), both in pellet form. The fungal microorganisms evaluated were: Aspergillus flavus, Aspergillus Aspergillus niger, Fusarium culmorum, Penicillium italicum, Pycnoporus sanguineus, isolated from different sources (leaves, fruits, agricultural soil, and vegetables). While, Pleurotus ostreatus was also provided by the Universidad Nacional Agraria la Molina (UNALM). The degradative capacity of the fungi was evaluated in two stages. The first was carried out in an incubator for a period of 46 days at 26°C using an artisanal culture medium (Potato Dextrose Agar, PDA). The highest degradation percentages of 2.85 % and 1.83% were achieved with Fusarium culmorum on HDPE and LDPE, respectively, followed by Pycnoporus sanguineus with 2.16% on HDPE and 1.73% on LDPE. These results were confirmed by Scanning Electron Microscopy (SEM), hyphae development, micelle formation, as well as cracks and striations on the surface of the plastic were observed. In a second stage, both fungi and polymers were evaluated for a period of 4 months, and a higher percentage of mass reduction was produced with Fusarium culmorum with values of 6.24% for HDPE and 7.81% for LDPE. The biodegradation of both polymers was evidenced, and further research is needed to im p ro ve efficiency by optimizing parameters such as time, temperature, and culture medium.
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