Respirometric index as a tool for biogas generation production from poultry manure

Over the past three following decades, poultry production has been strongly growing; for example, in the EU this growing has been around the 5% per year. Obviously this increasing determined a higher volume of livestock and poultry farming waste which represents a potential renewable fuel, suitable for waste to energy conversion. The poultry waste composition, the technical solution for energy recovery and the corresponding yields strongly depend on the biomass origin (animal species) and on the mode of farming (diet, housing, ambient growth, stage of production, etc.). In particular, a very important parameter is represented by moisture. In fact, if the moisture value is higher than 30% (minimum value for which the biological activity is not inhibited), it is possible to send the poultry manure to a biological process, such as the anaerobic digestion (AD). The purpose of this paper is to propose and describe a rapid method for assessing the potential of biogas in anaerobic poultry manure, with the goal of helping the choices of operators of AD. The tests normally applied for the measurement of the anaerobic biogasification potential (ABP) are reliable, but not practicable as a routine analysis. In fact, this kind of test is expensive and time consuming (from 21 days to determine the production of biogas partial up to 100 days for the total production of biogas). In this work it was proposed a fast, alternative: the dynamic respiration index (DRI). The application of this method allows a rapid determination of the value of the ABP (1-5 days). In addition, two dynamic respirometric approaches were considered: the first proposed by Di.Pro.Ve developed of the University of Milan, and the second developed by the University of Trento. The main difference between them is the control of temperature (not controlled in the first case, and being kept constantly in the second case)