Abstract: In recent years, the compression of date (Phoenix
dactylifera L.) fruit powders (DP) to obtain date tablets (DT) has
been suggested as a promising form of valorization of non
commercial valuable date fruit (DF) varieties. To further improve
and characterize DT, the present study aims to investigate the
influence of the DP particle size and compression force on some
physical properties of DT. The results show that independently of
particle size, the hardness (y) of tablets increases with the increase of
the compression force (x) following a logarithmic law (y = a ln (bx)
where a and b are the constants of model). Further, a full factorial
design (FFD) at two levels, applied to investigate the erosion %,
reveals that the effects of time and particle size are the same in
absolute value and they are beyond the effect of the compression.
Regarding the disintegration time, the obtained results also by means
of a FFD show that the effect of the compression force exceeds 4
times that of the DP particle size. As final stage, the color parameters
in the CIELab system of DT immediately after their obtaining are
differently influenced by the size of the initial powder.
Abstract: The agriculture lignocellulosic by-products are receiving increased attention, namely in the search for filter materials that retain contaminants from water. These by-products, specifically almond and hazelnut shells are abundant in Portugal once almond and hazelnuts production is a local important activity. Hazelnut and almond shells have as main constituents lignin, cellulose and hemicelluloses, water soluble extractives and tannins. Along the adsorption of heavy metals from contaminated waters, water soluble compounds can leach from shells and have a negative impact in the environment. Usually, the chemical characterization of treated water by itself may not show environmental impact caused by the discharges when parameters obey to legal quality standards for water. Only biological systems can detect the toxic effects of the water constituents. Therefore, the evaluation of toxicity by biological tests is very important when deciding the suitability for safe water discharge or for irrigation applications.
The main purpose of the present work was to assess the potential impacts of waters after been treated for heavy metal removal by hazelnut and almond shells adsorption systems, with short term acute toxicity tests.
To conduct the study, water at pH 6 with 25 mg.L-1 of lead, was treated with 10 g of shell per litre of wastewater, for 24 hours. This procedure was followed for each bark. Afterwards the water was collected for toxicological assays; namely bacterial resistance, seed germination, Lemna minor L. test and plant grow. The effect in isolated bacteria strains was determined by disc diffusion method and the germination index of seed was evaluated using lettuce, with temperature and humidity germination control for 7 days. For aquatic higher organism, Lemnas were used with 4 days contact time with shell solutions, in controlled light and temperature. For terrestrial higher plants, biomass production was evaluated after 14 days of tomato germination had occurred in soil, with controlled humidity, light and temperature.
Toxicity tests of water treated with shells revealed in some extent effects in the tested organisms, with the test assays showing a close behaviour as the control, leading to the conclusion that its further utilization may not be considered to create a serious risk to the environment.
Abstract: This work presents the experimental results obtained
at a pilot plant which works with a slow, wet and catalytic pyrolysis
process of dry fowl manure. This kind of process mainly consists in
the cracking of the organic matrix and in the following reaction of
carbon with water, which is either already contained in the organic
feed or added, to produce carbon monoxide and hydrogen. Reactions
are conducted in a rotating reactor maintained at a temperature of
500°C; the required amount of water is about 30% of the dry organic
feed. This operation yields a gas containing about 59% (on a volume
basis) of hydrogen, 17% of carbon monoxide and other products such
as light hydrocarbons (methane, ethane, propane) and carbon
monoxide in lesser amounts. The gas coming from the reactor can be
used to produce not only electricity, through internal combustion
engines, but also heat, through direct combustion in industrial
boilers. Furthermore, as the produced gas is devoid of both solid
particles and pollutant species (such as dioxins and furans), the
process (in this case applied to fowl manure) can be considered as an
optimal way for the disposal and the contemporary energetic
valorization of organic materials, in such a way that is not damaging
to the environment.
Abstract: An innovative approach utilizing highly alkaline oil
shale waste ash and carbon dioxide gas (CO2), associated with power
production, as a resource for production of precipitated calcium
carbonate (PCC) is introduced in this paper. The specifics and
feasibility of the integrated ash valorization and CO2 sequestration
process by indirect aqueous carbonation of lime-consisting ash were
elaborated and the main parameters established. Detailed description
of the formed precipitates was included. Complimentary carbonation
experiments with commercial CaO fine powder were conducted for
comparative characterization of the final products obtained on the
basis of two different raw materials. Finally, the expected CO2
uptake was evaluated.