Utilisation of poultry industry wastes for liquid biofuel production via thermal and catalytic fast pyrolysis.

The objective of this study was to examine the potential of poultry wastes to be used as feedstock in non-catalytic and catalytic fast pyrolysis processes, which is a continuation of our previous research on their conversion into biofuel via slow pyrolysis and hydrothermal conversion. Both poultry meal and poultry litter were examined, initially in a fixed bed bench-scale reactor using ZSM-5 and MgO as catalysts. Pyrolysis of poultry meal yielded high amounts of bio-oil, while pyrolysis of poultry litter yielded high amounts of solid residue owing to its high ash content. MgO was found to be more effective for the deoxygenation of bio-oil and reduction of undesirable compounds, by converting mainly the acids in the pyrolysis vapours of poultry meal into aliphatic hydrocarbons. ZSM-5 favoured the formation of both aromatic compounds and undesirable nitrogenous compounds. Overall, all bio-oil samples from the pyrolysis of poultry wastes contained relatively high amounts of nitrogen compared with bio-oils from lignocellulosic biomass, ca. 9 wt.% in the case of poultry meal and ca. 5-8 wt.% in the case of poultry litter. This was attributed to the high nitrogen content of the poultry wastes, unlike that of lignocellulosic biomass. Poultry meal yielded the highest amount of bio-oil and was selected as optimum feedstock to be scaled-up in a semi-pilot scale fluidised bed biomass pyrolysis unit with the ZSM-5 catalyst. Pyrolysis in the fluidised bed reactor was more efficient for deoxygenation of the bio-oil vapours, as evidenced from the lower oxygen content of the bio-oil.

Effects of spent liquor recirculation in hydrothermal carbonization.

In this study, the effect of the recirculation of spent liquor from hydrothermal carbonization was investigated depending on the biomass type (grape pomace, orange pomace and poultry litter). The yield and fuel properties of hydrochars and spent liquor characteristics were determined for each recirculation step. By recirculation, mass and energy yields of the hydrochar increased, but their combustion characteristics changed: the ignition temperature and combustion reactivity decreased. The organic and inorganic load of liquor was increased with recirculation number, but not as much as would be expected after the first recycle. It was concluded that the load of organic and inorganic species in spent liquor decreased the leaching of some inorganics and diffusion of the degraded soluble fragments from biomass in the subsequent hydrothermal carbonization. Overall, this study showed that spent liquor recirculation makes the overall hydrothermal carbonization process environmentally friendly.

Conversion of poultry wastes into energy feedstocks.

In this study, conversion of wastes from poultry farming and industry into biochar and bio-oil via thermochemical processes was investigated. Fuel characteristics and chemical structure of biochars and bio-oils have been investigated using standard fuel analysis and spectroscopic methods. Biochars were produced from poultry litter through both hydrothermal carbonization (sub-critical water, 175-250°C) and pyrolysis over a temperature range between 250 and 500°C. In comparison to hydrothermal carbonization, pyrolysis at lower temperatures produced biochar with greater energy yield due to the higher mass yield. Biochars obtained by both processes were comparable to coal. Hydrothermal liquefaction of poultry meal at different temperatures (200-325°C) was conducted and compared to optimize its process conditions. Higher temperatures favored the formation of bio-crude oil, with a maximum yield of 35wt.% at 300°C. The higher heating values of bio-oils showed that bio-oil could be a potential source of synthetic fuels. However, elemental analysis demonstrated the high nitrogen content of bio-oils. Therefore, bio-oils obtained from hydrothermal liquefaction of poultry meal should be upgraded for utilization as a transport and heating fuel.

Hydrothermal carbonization and torrefaction of grape pomace: a comparative evaluation.

Grape pomace was treated by hydrothermal carbonization (sub-critical water, 175-275°C) and torrefaction (nitrogen atmosphere, 250 and 300°C), with mass yield of solid product (char) ranging between 47% and 78%, and energy densification ratio to 1.42-1.15 of the original feedstock. The chars were characterised with respect to their fuel properties, morphological and structural properties and combustion characteristics. The hydrothermal carbonization produced the char with greater energy density than torrefaction. The chars from torrefaction were found to be more aromatic in nature than that from hydrothermal carbonization. Hydrothermal carbonization process produced the char having high combustion reactivity. Most interesting was the finding that aqueous phase from hydrothermal carbonization had antioxidant activity. The results obtained in this study showed that HTC appears to be promising process for a winery waste having high moisture content.

Activated carbon from leather shaving wastes and its application in removal of toxic materials.

In this study, utilization of a solid waste as raw material for activated carbon production was investigated. For this purpose, activated carbons were produced from chromium and vegetable tanned leather shaving wastes by physical and chemical activation methods. A detailed analysis of the surface properties of the activated carbons including acidity, total surface area, extent of microporosity and mesoporosity was presented. The activated carbon produced from vegetable tanned leather shaving waste produced has a higher surface area and micropore volume than the activated carbon produced from chromium tanned leather shaving waste. The potential application of activated carbons obtained from vegetable tanned shavings as adsorbent for removal of water pollutants have been checked for phenol, methylene blue, and Cr(VI). Adsorption capacities of activated carbons were found to be comparable to that of activated carbons derived from biomass.