Fallen leaves in cities are often treated as waste; therefore, they are collected, transported outside urban areas, and composted, which contributes to greenhouse gas (GHG) emissions. Instead of this conventional management approach, fallen leaves could be utilized as a feedstock in biogas production,
[...] Read more.
Fallen leaves in cities are often treated as waste; therefore, they are collected, transported outside urban areas, and composted, which contributes to greenhouse gas (GHG) emissions. Instead of this conventional management approach, fallen leaves could be utilized as a feedstock in biogas production, helping to reduce GHG emissions, increase renewable energy generation, and provide fertilizer. The aim of this study was to compare the mono-digestion of fallen leaves from three tree species commonly found in parks and along streets—northern red oak (
Quercus rubra L.), small-leaved lime (
Tilia cordata Mill.), and Norway maple (
Acer platanoides L.)—in both wet and dry anaerobic digestion (AD) systems. A biochemical methane potential (BMP) test was conducted in batch assays for each of the three substrates in both AD technologies at a temperature of 38 ± 1 °C. The highest specific methane yield (SMY) was obtained from
Quercus leaves in wet AD technology, with a methane yield of 115.69 ± 4.11 NL kg
VS−1. The lowest SMY (55.23 ± 3.36 NL kg
VS−1) was observed during the dry AD of
Tilia leaves. The type of technology had no significant impact on the SMY of
Acer and
Tilia leaves; however, the methane yield from
Quercus leaves in wet AD was significantly higher (
p < 0.05) than that from dry AD. Studies on the use of fallen leaves from
Tilia cordata,
Quercus rubra, and
Acer platanoides as substrates in mono-digestion technology have shown their limited suitability for biogas production. Nevertheless, this feedstock may be more effectively used as a co-substrate, mainly due to the low concentrations of ammonia (NH
3) and hydrogen sulfide (H
2S) in the biogas produced from these leaves, both of which are considered inhibitors of the AD process.
Full article
