Thermodynamic Analysis of Digestate Pyrolysis Coupled with CO2 Sorption

To date the management of digestate is a crucial task for anaerobic digestion process. In the present work a strategy for digestate management is thermodynamically analyzed by a commercial software for process simulation called CHEMCAD®. Pyrolysis of digestate is simulated by a minimization of the free Gibbs energy. The sequestration of the carbon dioxide (CO2) released by the pyrolysis is investigated by the addition of calcium oxide, in order to reduce CO2 emissions. The effect of the pyrolysis temperature between 400–900 °C and of the CaO/digestate mass ratio between 0–0.5 was discussed, as well. The CHEMCAD application allowed to investigate the chemisorption behaviour by focusing on the temperature-dependent CO2 sorption trends in relation to different values of the CaO mass ratio. Temperature below 650 °C should be considered for CO2 sorption by CaO. CO2 molar fraction below 10% was obtained for temperature below 450 °C and CaO/digestate mass ratio higher than 0.4

First results on the evaluation of the ground-cover biodiversity in an agroforestry poultry system

The first results on the impact of hen grazing on ground cover composition and biodiversity of two hazelnut orchards (sites A and B) in the southern Italy are presented. The selected sites were characterized by different size and environmental conditions that were, respectively for A and B: area, 4 and 5 ha; altitude, 525 and 660 m a.s.l.; annual mean temperature, +12°C and +13°C; annual precipitation: 730 and 780 mm. Besides, ground covers of the sites were different for plant species presence and distribution. In each site three 120 m2 areas were considered, each of which was provided with a mobile coop (5 hens/m2) to house during the night ten 25-week-old commercial egg-laying chickens. The trial started the first decade of May 2019. The use of hen grazing affected quantitatively and qualitatively the herbaceous stratum of the study sites, as the number of taxa composing the ground cover decreased in both sites, whereas the relative frequencies varied (increased or decreased) according to the taxon. By computing different indices of alpha diversity, we observed significant differences in species richness and diversity after hen grazing only in one site. However, the value of the qualitative Sørensen index showed a high overlap in the assemblage of ground cover before and after hen grazing in both sites. By comparing the sites, we found that, at the beginning of the trial, the ground cover of one site was richer and more diverse compared to the other site; however, the reverse situation occurred after hen grazing. Overall, our results indicate that integrating fruit trees with poultry may play a positive role in an agroforestry context, mainly in terms of control of vegetation growth