SVILUPPO DI TECNOLOGIE INNOVATIVE PER LA CARATTERIZZAZIONE DEGLI EFFLUENTI DI ALLEVAMENTO AI FINI DELLA LORO VALORIZZAZIONE AGRONOMICA ED ENERGETICA

Currently there are two important issues related to the management of manure. The first concerns the agronomic use of effluent. Very often, during deployment in the field, the nutrient content is unknown or underestimated. The second concerns the treatment of anaerobic digestion - widely used to treat effluents - because in many cases the process does not proceed optimally because those who manage not have the necessary skills. At the time the laboratory analysis are the only way to get information. However this system is expensive, impractical in sampling and slow to deliver the results with respect to the requirements dictated by the timing of the distribution field and in the anaerobic digestion process. The need to have available analytical data at farm level when required and at a reasonable cost, has led to carry out specific research activities. A first set of technologies tested by many authors for the indirect analysis of the nutrient content in manure, regards physico-chemical and electrical measures. These are represented by the measurement of electrical conductivity (EC), which has a good correlation with the content of ammonia nitrogen and potassium; density that has good correlations with the content of dry matter and phosphorus and pH as a parameter of support for EC and density. The second technology examined is the near-infrared spectroscopy - NIR. Many authors have already successfully used to analyze manure and digestate with limited errors, to predict the content of total nitrogen, ammonia nitrogen, volatile fatty acids and dry matter. Then, we studied how to simplify complex technologies and then make transferable from the laboratory to the field, able to measure the amount of nutrients and volatile fatty acids contained in the livestock slurry and digestate. In this study we tried to identify the analytical methods and the best technological solutions to be transferred to prototype devices to be used in farm. At this stage, we tried to understand which factors could affect the measurement quality, functionality and cost of construction of the prototype. The development of prototypes has led to realize two devices, prototype EPD (to measure Electrical conductivity, pH and density) and the prototype NIR. The reliability of the prototypes to support the agronomic use of manure, can be refined considering the information relating to the management of livestock (housing, feeding and manure management). In the context of the energy recovery of manure, the information obtained from the prototypes, they may become more important if integrated within the system to support the management of anaerobic digestion plants, based on fuzzy logic. The experimental tests have confirmed a general ability of the measuring system to predict dry matter, nitrogen, phosphorus and the AGVs contained in slurries and digestates. There are still critical issues and it is therefore necessary to continue with further study of the measurement system. Ultimately, the use of indirect methods and tools to be used for in situ characterization of the effluents can lead to a significant improvement of the environmental and energy enhancement of the manure towards sustainable intensive agriculture.