Harvesting zero waste from co-digested fruit and vegetable peels via integrated fermentation and pyrolysis processes

Abstract

The aim of this study is to assess an innovative economic approach for the production of both fermentative hydrogen and biochar from fruit and vegetable peels (FVPs) via fermentation/pyrolysis process. Firstly, in fermentation batches, multi-fermentation of FVPs positively affected the harvested hydrogen yield and COD reduction efficiency, which reached their maximal values of 3.9 ± 0.6 mmol/g COD and 56.2 ± 4.6% at batch of 25% pea + 25% tomato + 25% banana + 25% orange (M4). Secondly, digestates produced from all batches were pyrolyzed at 500°C for investigating the potential for biochar production. Based on the characteristics of the pyrolyzed digestate, biochar produced from S1 (spinach) exhibited the highest specific surface area, density, pore volume, biochar production yield, and pyrolysis profit of 28.43 ± 3.95 m 2 /g, 1.93 ± 0.18 g/cm 3 , 0.59 ± 0.08 cm 3 /g, 59.04 ± 2.36%, and 3.66 $/kg feedstock , respectively. However, the maximum overall profit from both fermentation and pyrolysis processes was 5.21 $/kg feedstock and was denoted for M4.

Impacts of Chemical-Assisted Thermal Pretreatments on Methane Production from Fruit and Vegetable Harvesting Wastes: Process Optimization

“…Although EU greenhouse gas emissions from landfills have already declined due to the well-practiced MSW managements [4], the degradation of FVHW during landfilling causes the production of leachates and emissions of greenhouse gases all around the world. Furthermore, uncontrolled burning has also resulted in greenhouse gases and toxic compounds [5].…”

“…On the other hand, FVHW, primarily non-commercial parts of plants such as leaves, bodies, stems as well as unmerchantable fruits and vegetables, have a milder lignocellulosic structure than the other agricultural residues and require less severe pretreatment conditions before AD. There have been very limited studies investigating the methane production potentials of mixed FVHW combined with pretreatment methods in the literature [3,5,[14][15][16][17].…”

Sustainable Horticultural Waste Management: Industrial and Environmental Perspective

“…The pollutant emissions are lower in this disposal process as there is absence of oxygen and with low processing temperature, although emissions of other compounds simultaneously could increase with lower oxygen ratio [44]. Biochar production can be done by fruits and vegetable peels and other residues from, for example, spinach, bananas, peas, and tomatoes [45]. There are two types of pyrolysis, i.e., slow and fast.…”

Biochar and Energy Production: Valorizing Swine Manure through Coupling Co-Digestion and Pyrolysis

“…However, this technology is still expensive when global valorization of all side-streams is intended. Thus, the conversion of digestate into valuable pyrolysis products seems a reasonable choice, as shown by different authors when evaluating the feasibility of pyrolysis as the final treatment option of microbial processes [72,73], but the costs of implementing this technology either as a stand-alone configuration or along with other technical options is still too high. Piñas et al [74] demonstrated that biogas plants presented viability for electrical power higher than 740 kWe The penalizing effect of diverting pyrolysis products and using a portion of digestion gas to supply energy to cover the heat demand of the global process is easily observed from the inverse trend shown on these two graphics.…”