A THERMODYNAMIC FEASIBILITY EVALUATION MODEL FOR THE EFFICIENT STRUVITE PRODUCTION FROM LIVESTOCK WASTE

摘要

Inefficient management of anthropogenic organic waste from agricultural sources (e.g., animal manure) results in nutrient pollution and can negatively affect public health and increase human impact on the environment. Therefore, an effective management strategy for livestock waste processing is necessary. In this contribution, a thermodynamic model is developed to design feasible and efficient struvite production as a technology for nutrients recovery from cattle digestate. Cattle digestate presents a high concentration of calcium ions which compete with magnesium for the struvite precursor ions, being able to inhibit struvite formation. An additional hindrance is the variability in the composition of cattle manure, which largely affects the formation of struvite due to the changes in the distribution of the reagent compounds. This feedstock composition variability is studied through a probabilistic framework. Struvite formation is found as a suitable method to recover nutrients from digestate, achieving efficiencies up to 80%, although an individual analysis of raw material for each case is desirable to adjust the operational parameters and optimize the nutrients recovery process from livestock waste.