The control of the processes and the operation of wastewater treatment plants (WWTP) are carried out to ensure compliance with the legislative requirements imposed by the European Union. Because a large number of variables are daily measured, a coherent and structured approach to such a system is required to understand its inherent behaviour and performance efficiency. For this purpose, the physicochemical parameters are widely used as a reliable evaluation procedure that allows us to check the quality of the tributary and effluent to the plant. However, due to the large amount of data available on a daily basis, the great variability of the processes that occur in the WWTP and seasonal variations, it is difficult to evaluate the overall performance with univariate simple statistical methods. In this sense, both principal component analysis (PCA) and hierarchical clusters analysis (HCA) are multivariate techniques that have been extensively applied to extract and structure information for different purposes. In this PhD, both statistical tools are applied to the dataset over a three-year period of an urban WWTP located in Cartagena (Southeast of Spain), an area with special characteristics related to the geochemical composition of the water and an important use of fertilizers. Four main factors were extracted in association with the nutrients, the ionic component, the organic load of the WWTP and the efficiency of the whole process. The analysis of hierarchical groupings (HCA) allowed us to distinguish between influent and effluent parameters, although a deeper analysis gave rise to a dendrogram with groupings similar to those obtained for the analysis of main components.
Resumen -AbstractJoaquín López-Castellanos García IV On the other hand, the optimization of the exploitation efficiency of an urban WWTP requires a correct management of its sludge, maximizing the time of use of its anaerobic digesters, among other factors. In this sense, this PhD presents the use of the hydrocyclone technique in the sludge line, recovering the useful capacity of the anaerobic digester after years of continuous operation and as an alternative to emptying it for maintenance and cleaning. The coarse fraction recovered prior the use of the hydrocyclone plant was observed to contain still potentially biodegradable matter, which could be used as soil amendment, with low concentrations of heavy metals. The hydrocyclone system showed a separation capacity over time for all types of solids, with higher concentration factors for fixed solids than for total or volatile solids, always being higher in the warmer seasons. X-ray diffraction analysis showed the presence of quartz in the fines fraction, which indicated its possible use as a building material or ceramic. In addition, it was observed that the formation of struvite increased with the increase of phosphorus and magnesium in the different fractions, as well as a concentration in the levels of chromium in the whole process with respect to the influent to the hydrocyclone, although...
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