A feasibility study of agricultural and sewage biomass as biochar, bioenergy and biocomposite feedstock: production, characterization and potential applications.

In this study, we pyrolysed six waste derived biomass: pine sawdust (PSD), paunch grass (PG), broiler litter (BL), sewage sludge (SS), dewatered pond sludge (DWP), and dissolved air-floatation sludge (DAF) into biochar. Biochars were characterized using scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, Fourier transform infrared spectroscopy, inductively-coupled plasma mass spectrometry, (13)C-solid-state nuclear magnetic resonance spectroscopy, and X-ray photoelectron spectroscopy to evaluate their feasibility for potential agronomic and environmental applications. Syngas produced during the pyrolysis process was also analyzed to determine the energy values. Results show that PSD biochar has the utmost potential for carbon sequestration and contaminant remediation due to its high surface area, aromaticity and carbon content. Additionally given its low ash content, PSD biochar could also potentially be used as filler in wood plastic biocomposites. Low levels of heavy metals (Cr, Cu, Zn, As, Cd, Hg, and Pb) in all biochars suggest that biochars are also applicable for land application according to the United States Environmental Protection Agency regulation 40 CFR part 503. The composition of syngas evolved during the pyrolysis of feedstocks showed little difference in the calorific values, ranging from 12-16 MJ/dsm with PSD having the maximum calorific value of 16 MJ/dsm.

Chemical composition of composted grape marc.

Composted grape marc, produced at the vineyard using different procedures, is generally returned into the vineyard. Information on the chemical composition of these grape marc composts is lacking, particularly the variability that may result from different composting practices. In this study, grape marc composts, varying in age from 3 months to 3 years, were collected from four different vineyards and subjected to detailed chemical analysis. The chemical analysis revealed that all the grape marc composts contained levels of free potassium, in the range of 2-3% w/w. Plant macronutrients such as Ca, S, Mg were present at low levels (<1% w/w), while phosphorus (0.1-0.3% w/w) and nitrogen (1-2% w/w) levels were not very high and mainly present in "plant unavailable" form. The levels of soluble salts, though not excessive, were elevated in all the composts. These salt levels could cause a problem in some soils. Heavy metals were not present in any significant levels. All the grape marc composts analysed provided some benefit in returning nutrients into the vineyard and all were significant potassium sources.