Universidad Nacional Agraria La Molina. Escuela de Posgrado. Doctorado en Ingeniería y Ciencias Ambientales

Traditional methods of leather production in Peru consume on average between 60 to 80% of chromium for tanning process , generating wastewater with high concentrations of total chromium that must be treated in order to meet the Maximum Allowable Values ( VMA ) established by the DS 029-2009 - Vivienda. The use of complexing agents in the chrome tanning process reduces the supply of chromium to increase skin absorption. The main objective of this study was to evaluate the treatability by chemical precipitation of wastewater from traditional and alternative tanning process. It was determined that the optimal pH for the precipitation was between 7.36 and 9.99, the doses used besides sodium hydroxide were between 0.5 and 5.5 g / L, is the traditional process that requires higher dose . It was determined that the cost of the inputs used in the production of wet blue leather is more than the c...

ENVIRONMENTAL POLLUTION FROM MICROPLASTICS (MPS), AN ANTHROPOGENICALLY MEDIATED MENACE TO THE BIOSPHERE, IS A GLOBAL CONCERN. THIS RESEARCH CONDUCTED A BIBLIOMETRIC ANALYSIS OF MPS IN SOIL AND TERRESTRIAL ECOSYSTEMS USING R SOFTWARE AND BIBLIOSHINY TO ANALYZE DESCRIPTIVE STATISTICS, AUTHOR CONTRIBUTIONS, DOCUMENTS, AND CONCEPTUAL STRUC-TURES. THE SCOPUS DATABASE WAS SELECTED, AND VARIOUS KEYWORDS OPTIMIZED THE SEARCH. AN ANALYSIS OF RESEARCH TRENDS DIVIDED THE TIMELINE INTO THREE PERIODS: PERIOD I (2012–2018), PERIOD II (2019–2021), AND PERIOD III (2022). RESULTS SHOWED WANG J. AS THE AUTHOR WITH THE HIGHEST H-INDEX, WHILE SCIENCE OF THE TOTAL ENVIRONMENT HAD AN H-INDEX OF 43. IN PERIOD I, RESEARCH FOCUSED ON MPS AND PLASTIC POLLUTION, RAISING QUESTIONS ABOUT THEIR IMPACTS ON TERRESTRIAL ECOSYSTEMS. RESEARCH FOUND THAT MPS NEGATIVELY AFFECTED SOIL ORGANISMS BY DECREASING GROWTH RATES...

THE OBJECTIVE OF THE RESEARCH WAS TO DETERMINE THE DIGESTIBILITY OF THE NUTRITIONAL FRACTIONS OF PALM KERNEL CAKE AND TO ESTIMATE THE DIGESTIBLE ENERGY REQUIRED FOR THE FORMULATION OF RATIONS ACCORDING TO THE ANIMAL SPECIES. TEN MALE GUINEA PIGS (BODY WEIGHT: 725 ± 38 G) WERE DISTRIBUTED IN INDIVIDUAL METABOLIC CAGES. THE CONTROL GROUP (N: 5) WAS FED 100% WHEAT BRAN AND THE EXPERIMENTAL GROUP 40% PALM KERNEL CAKE AND 60% WHEAT BRAN. BOTH DIETS CONTAINED THE MINIMUM VITAMIN C REQUIREMENT. THE ADAPTATION PHASE TO THE NEW FEED LASTED 10 DAYS. FOR THE NEXT FIVE DAYS, 50 G OF FEED WAS FED AND FECES WERE COLLECTED DAILY. THE NUTRIENT DIGESTIBILITY COEFFICIENTS DETERMINED BY THE INDIRECT METHOD WERE 69; 70; 81; 61; 66 AND 53% FOR DRY MATTER, CRUDE PROTEIN, ETHER EXTRACT, CRUDE FIBER, NITROGEN FREE EXTRACT AND ASH, RESPECTIVELY. THE DIGESTIBILITY COEFFICIENTS, MULTIPLIED BY THEIR CALORIC VALUES...

In the present study, the stabilization of horse manure (mixture of rice husk, manure and horse urine) was evaluated through an aerobic process similar to composting. The stabilization process was evaluated in two piles of horse manure for 16 weeks, taking samples every week. A decrease in temperature from 66,7 to 41,0 °C, the reduction of the density from 394,0 to 370,4 kg/m3, the reduction of the water retention capacity from 220,7 to 125,6% and the reduction of the respiratory activity of 9.8 to less than 2 mgO2/g ms/d, were indicators of the stabilization of the horse manure, the easily degradable material of manure and urine were removed by aerobic degradation and washed with irrigation, leaving only the rice husk with a minimum fraction of other materials. On the other hand, the increase in total nitrogen and a decrease in the C/N ratio at the end of the week 16 were indicative of...