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Engineering methods should be constantly updated to promote constructive, economic, and sustainable improvements. In this work, new data on energy valorization and treatment of cattle wastewater through a UASB reactor operated at 40°C has been obtained. A semi-continuous feeding regime was applied, with hydraulic retention times of 6, 5, 3, and 2 days, and organic loading rates of 4, 5, 7, and 11 kg COD m-3 d-1. Gas volumes of up to 1.5 m³ biogas m-3 reactor d-1, with methane concentrations ranging between 69% and 75%, were recorded. Organic matter removals of 60-80% (total COD) and 50-75% (soluble COD) resulted in methane yields of 0.16-0.18 m³ CH4 kg-1 total COD and 0.4-0.5 m³ CH4 kg-1 soluble COD. No accumulation of volatile fatty acids was observed at any stage, and the pH and alkalinity values remained within the ideal range for the development of the anaerobic digestion process. The UASB reactor demonstrated significant biogas production and reasonable removal efficiency of solids and organic matter, indicating it as a new option for high concentration of pollutants treatment with the benefit of clean energy production. [ABSTRACT FROM AUTHOR]

Monitoring the spatial variability of soil attributes is an important tool in crop management. Multivariate statistical methods and geostatistics were jointly applied to evaluate the influence of different attributes on spatial variability in the soil. The aim of this research was to apply multivariate principal component analysis to map the spatial variability of the soil in an area subjected to different methods of conservation management and identify the most relevant physical and chemical attributes. Disturbed and undisturbed soil samples were collected and georeferenced at 99 different points in the study area at depths of 0.00-0.10 m and 0.10-0.20 m to measure the physical and chemical attributes of the soil; multivariate principal component analysis (PC) was then applied to the data. Geostatistics was applied to the PCs showing greater explanatory capacity, evaluating spatial dependence, and generating maps of spatial variability. The variance in the soil attributes was explained by the first eight PCs. Soil density, particle density and pH had the greatest influence on the spatial variability of the soil since they showed the highest correlation with the PC with the greatest explanatory power. The PCs that correlated with at least two of the soil attributes showed moderate (PC1 and PC6) and strong (PC2, PC4 and PC5) spatial dependence. The generated maps helped identify the joint influence of the variability of the most relevant attributes, making it possible to characterise regions under different methods of conservation management. [ABSTRACT FROM AUTHOR]

Copyright of Colloquium Agrariae is the property of Asociacao Prudentina de Educacao e Cultura (APEC) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Colloquium Agrariae is the property of Asociacao Prudentina de Educacao e Cultura (APEC) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Engenharia na Agricultura is the property of Engenharia na Agricultura and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)