Biofuel Production and Phosphorus Recovery through an Integrated Treatment of Agro-Industrial Waste

Alessio Siciliano, Carlo Limonti, Sanjeet Mehariya, Antonio Molino and Vincenza Calabrò
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Alessio Siciliano: Department of Environmental and Chemical Engineering, University of Calabria, Via P. Bucci cubo 44B, 87036 Arcavacata di Rende (CS), Italy
Carlo Limonti: Department of Environmental and Chemical Engineering, University of Calabria, Via P. Bucci cubo 44B, 87036 Arcavacata di Rende (CS), Italy
Sanjeet Mehariya: Department of Sustainability; Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), P. Enrico Fermi 1, 80055 Portici (NA), Italy
Antonio Molino: Department of Sustainability; Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), P. Enrico Fermi 1, 80055 Portici (NA), Italy
Vincenza Calabrò: Department of Informatics, Modelling, Electronics and Systems Engineering, University of Calabria, Via P. Bucci cubo 39C, 87036 Arcavacata di Rende (CS), Italy

Sustainability, 2018, vol. 11, issue 1, 1-17

Abstract: The present study aimed to develop an integrated treatment of agro-industrial waste for biofuel (biogas and syngas) production and for phosphorus recovery. In the first step, an anaerobic digestion (AD) process was carried out on two different mixtures of raw agro-industrial residues. Specifically, a mixture of asparagus and tomato wastes (mixture-1) and a mixture of potatoes and kiwifruit residues (mixture-2) were investigated. The results proved that the properties of mixtures notably affect the evolution of the digestion process. Indeed, despite the lower organic load, the maximum biogas yield, of about 0.44 L/gCOD removed , was obtained for mixture-1. For mixture-2, the digestion process was hindered by the accumulation of acidity due to the lack of alkalinity in respect to the amount of volatile fatty acids. In the second step, the digestates from AD were utilized for syngas production using supercritical water gasification (SCWG) at 450 °C and 250 bar. Both the digestates were rapidly converted into syngas, which was mainly composed of H 2 , CO 2 , CH 4 , and CO. The maximum values of global gasification efficiency, equal to 56.5 g/kgCOD, and gas yield, equal to 1.8 mol/kgTS, were detected for mixture-2. The last step of the integrated treatment aimed to recover the phosphorus content, in the form of MgKPO 4 ?6H 2 O, from the residual liquid fraction of SCWG. The experimental results proved that at pH = 10 and Mg/P = 1 it is possible to obtain almost complete phosphorus removal. Moreover, by using the scanning electronic microscopy, it was demonstrated that the produced precipitate was effectively composed of magnesium potassium phosphate crystals.

Keywords: anaerobic digestion; biogas; biomass; magnesium potassium phosphate; supercritical water gasification (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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