K Nn mK - Amecamex.org.mx

FSB1 – 2004
Food Science and Biotechnology in Developing Countries
Residues
Fiber
Pectin Lignin Cellulose
Total Insoluble Soluble
Potato peel [30] 73 6.2 b
16 13.8 16
Potato pulp 15.8 9.4 6.4 ~15 [31] - -
Soy bean shells 64.6 56.9 7.7 - - -
Sugar beet pulp 75.3 50.1 25.2/ 22.1 [32] 30 [33] / 26 [34] 1.85 [32] / 4.56 [34] 23/ 27.2 [32]
White wine pomace 58.6 56.3 2.3 3.9 [25] / 5.5 [35] 41.2 [25] / 53.6 [35] -
Results expressed as percentage of original dry matter, - no data available, b= as hemicellulose
To view vegetable waste recovery processes as potential goldmines is typically overly optimistic, as
the costs of extraction and purification of the components generally reduce the profit margins available
to levels that are barely economic, as already described.
For this reason the third example is focused on the creation of ‘bioadsorbents’ to be used in waste
water treatment with improved functionality, using their natural content of adsorptive components or
enhancing their adsorption rate by combination of favored raw materials.
Adsorption happens on the interface; therefore an important criterion for the effectiveness of
adsorbents is its surface area. Several methods are available to reach as large as possible surface
area like fine grinding, chemical or biochemical modification, or creating a specific structure. Hence
there is a relation between the natural properties of vegetable material and the requirements for high
quality adsorbents which could be matched during adaptation processing, as visualized in Figure 3.
decent
moderate
moderate
adsorption rate
surface area
chemical stability
possible
regeneration easy
Residual matter low, easy disposal life cycle
long
Adsorbens
good macropores : micropores 50:50
low
chemical inertness high
acceptable pore size distribution decent
very cheap
prize
low
bulk ware
handling
easy
Figure 3 Natural properties of vegetable waste (average) and expected product profile for carbons at
waste water treatment
Effective adsorption is feasible without physical or chemical activation. Several vegetable residues
have been used as bioadsorbents for waste water treatment so far. The raw material has only been
cut, dried, and ground before the experiments; important influencing parameters arise. We did series
of experiments with different residues, checking their ability to adsorb waste water components.
Toluene representing a substance of oecotoxic relevance has been tested in aqueous solution. The
adsorbing conditions were determined while changing the influencing process parameters. As
bioadsorbents we have used olive press cake, dried and ground to different particle sizes.
high
high
good