The main aim of the study presented in this paper was to evaluate the energy performance of anaerobic digestion of fruit and vegetable wastes (FVW) on a pilot scale in mesophilic conditions (35 °C), without the addition of any other kind of co-substrate. The anaerobic digestion experiment was carried out in a semi-continuous tubular horizontal reactor (1.13 m3) and lasted 6 months to take into account all the possible changes in feedstock composition during different periods of the year. Throughout the experiment the feedstock was characterized by measuring the total solid content, volatile solid content and higher heating value. The composition and energy contents of the biogas produced and the residue sludge were also evaluated. The results of the study demonstrate that fruit and vegetable wastes lead to high biogas yields and high methane contents. In particular, an average biogas yield of 0.80 Nm3 /kgvs and a specific methane yield of 0.45 Nm3 /kgvs were obtained. Since biogas is mainly used for energy production, a cumulative calculation of the energy content of feedstock, biogas and digestate during the whole experiment was carried out. At the end of the experimental period the energy content of the biogas produced was about 60% of the feedstock energy input, the residual energy content of the digestate was 15%, while the remaining 25% was the energy content of the biomass contained within the reactor. Energy conversion efficiency increases to about 80% by taking into account the biogas that would be produced by the biomass contained within the reactor. It is very interesting to note that the energy content of the reactor remains almost constant when the steady state is completely reached.
Energy performance assessment of mesophilic anaerobic digestion of fruit and vegetable wastes in a pilot-scale reactor
COCCO, DANIELE;PETROLLESE, MARIO;Demontis V;
2014-01-01
Abstract
The main aim of the study presented in this paper was to evaluate the energy performance of anaerobic digestion of fruit and vegetable wastes (FVW) on a pilot scale in mesophilic conditions (35 °C), without the addition of any other kind of co-substrate. The anaerobic digestion experiment was carried out in a semi-continuous tubular horizontal reactor (1.13 m3) and lasted 6 months to take into account all the possible changes in feedstock composition during different periods of the year. Throughout the experiment the feedstock was characterized by measuring the total solid content, volatile solid content and higher heating value. The composition and energy contents of the biogas produced and the residue sludge were also evaluated. The results of the study demonstrate that fruit and vegetable wastes lead to high biogas yields and high methane contents. In particular, an average biogas yield of 0.80 Nm3 /kgvs and a specific methane yield of 0.45 Nm3 /kgvs were obtained. Since biogas is mainly used for energy production, a cumulative calculation of the energy content of feedstock, biogas and digestate during the whole experiment was carried out. At the end of the experimental period the energy content of the biogas produced was about 60% of the feedstock energy input, the residual energy content of the digestate was 15%, while the remaining 25% was the energy content of the biomass contained within the reactor. Energy conversion efficiency increases to about 80% by taking into account the biogas that would be produced by the biomass contained within the reactor. It is very interesting to note that the energy content of the reactor remains almost constant when the steady state is completely reached.
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