Effect of different rates of spent coffee grounds (SCG) on composting process, gaseous emissions and quality of end-product.
The use of spent coffee grounds (SCG) in composting for organic farming is a viable way of valorising these agro-industrial residues. In the present study, four treatments with different amounts of spent coffee grounds (SCG) were established, namely, C0(Control), C10, C20and C40, containing 0, 10, 20 and 40% of SCG (DM), respectively; and their effects on the composting process and the end-product quality characteristics were evaluated. The mixtures were completed with Acacia dealbata L. shoots and wheat straw. At different time intervals during composting, carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions were measured and selected physicochemical characteristics of the composts were evaluated. During the composting process, all treatments showed a substantial decrease in total phenolics and total tannins, and an important increase in gallic acid. Emissions of greenhouse gases were very low and no significant difference between the treatments was registered. The results indicated that SCG may be successfully composted in all proportions. However C40, was the treatment which combined better conditions of composting, lower GHG emissions and better quality of end product.
CITAB Centre for the Research and Technology of Agro-Environment and Biological Sciences, Universidade de Trás-os-Montes e Alto Douro, Quinta de Prados, 5000-801 Vila Real, Portugal. Electronic address: cisantos@utad.pt.
Cátia
C
Santos
Universidade de Trás-os-Montes e Alto Douro, Quinta de Prados, 5000-801 Vila Real, Portugal.
João
J
Fonseca
CITAB Centre for the Research and Technology of Agro-Environment and Biological Sciences, Universidade de Trás-os-Montes e Alto Douro, Quinta de Prados, 5000-801 Vila Real, Portugal.
Alfredo
A
Aires
Chemistry Centre, Department of Soil Science, Universidade de Trás-os-Montes e Alto Douro, Quinta de Prados, 5000-801 Vila Real, Portugal.
João
J
Coutinho
CITAB Centre for the Research and Technology of Agro-Environment and Biological Sciences, Universidade de Trás-os-Montes e Alto Douro, Quinta de Prados, 5000-801 Vila Real, Portugal.
Henrique
H
Trindade
D000045:Acacia / Q000737:chemistry; D002245:Carbon Dioxide / Q000032:analysis / Q000378:metabolism; D003069:Coffee / Q000737:chemistry* / Q000378:metabolism; D005308:Fertilizers; D005707:Gallic Acid / Q000378:metabolism; D008697:Methane / Q000032:analysis / Q000378:metabolism; D009609:Nitrous Oxide / Q000032:analysis / Q000378:metabolism; D018547:Plant Stems / Q000737:chemistry / Q000378:metabolism; D012987:Soil / Q000737:chemistry; D013696:Temperature; D014908:Triticum / Q000737:chemistry / Q000378:metabolism
D003069:Coffee; D005308:Fertilizers; D012987:Soil; D002245:Carbon Dioxide; D005707:Gallic Acid; D009609:Nitrous Oxide; D008697:Methane
Acacia dealbata; Coffee grounds; Compost; Greenhouse gases; Phytochemicals