The following text was automatically extracted from the image on this page using optical character recognition software:
WASTE CHARACTERISITICS
Production rates and composition of solid wastes have
been described in previous reports (Wydeven, et al.,
1989,1990, Upadhye, et al., 1993). Some of the types of
waste include feces, trash, and inedible biomass. In a
bioregenerative system with full food production the
inedible biomass is the largest component of waste.
Inedible biomass is the most important waste stream to
be processed in order to reclaim carbon dioxide and
nutrients. Feces is an important waste to consider
because it is hazardous. Table 1 shows the elemental
composition of wheat straw (and for comparison, feces).
Wheat straw is a significant and representative
component of inedible biomass. Inedible biomass such
as wheat straw can be used to make activated carbon.
Table 1. Characteristics of Wastes -Wheat Straw
(Fisher, et al., 1998)
Parameter Feces Dried Wheat
(elemental Straw
composition
based on dry
weight basis)
Moisture Content 65-85% 0%
C 43% 42%
H 6.3% 5.6%
N 2.4% 1 %
O n/a 42%
S n/a 0.1%
Elemental Ash 10-15% 8-11%
Table 2 shows an analysis of a sample of wheat straw
including a breakdown of the ash component of the
wheat straw.
FLUE GAS COMPOSITION
Combustion of the inedible portion of hydroponically
grown crops and wastes such as human feces produces
mostly carbon dioxide, water, and ash. However, flue
gas typically also contains small quantities of uncom-
busted hydrocarbons, carbon monoxide, and other
contaminants. Organically bound nitrogen and sulfur can
produce the contaminants NO, and SO2 in the flue gas.
Table 3 shows the production of contaminants from
incineration of a life support waste. Note that even
though sulfur is present in the waste being burned, sulfur
dioxide is not observed in the flue gas. Alkali metals in
the waste can cause sulfur to leave the system in the
ash as sulfate (Nordin, 1995).
Table 2. Ultimate and Ash Analysis of Wheat Straw
(Fisher, et al., 1998)
Table 3. Flue Gas Emissions from Combustion of
Simulated Feces as a Function of Oxygen
Stoichiometry (Fisher, et al., 1998)
Sample 1 2 3 4
CONDITIONS
Feed Rate /hr 794 794 760 760
Air Flow sl m 62.8 51 41.5 40.1
Stoichiometric Ratio 1.51 1.13 1.01 0.92
Bed Temperature K 1071 1083 975 978
Pressure (atm.) 0.91 0.9 0.89 0.89
EMISSIONS
02(%) 6.26 1.99 0 0
C02 % 10.45 13.61 14.54 15.44
CO (3% Q) (ppm) 14506 17830 22613 26033
THC (3% 02) (ppm) 313 945 6310 6377
NOx (3%02) (ppm) 790 660 216 337
SO, (ppm) <0.5 <0.5 <0.5 <0.5
ULTIMATE ANALYSIS
CARBON (%) 36.32
HYDROGEN (%) 5.19
OXYGEN (%) 40.09
NITROGEN (%) 3.04
SULFUR (%) 0.67
ASH (%) 14.69
Total (%) 100
BTU/LB 6144
VOL. MATTER (%) 67.49
FIXED CARBON (%) 12.44
WATER (%) 5.38
ASH ANALYSIS
A1203 (%) 0.01
CaO (%) 9.13
Fe2O3 (%) 0.52
MgO (%) 4.89
MnO2 (%) 0.1
P205 (%) 8.87
K20 (%) 54.14
Si02 (%) 0.04
Na20 (%) 0.02
S03(%) 10.11
TiO2 (%) < 0.01
Total (%) 87.83
FORMS of SULFUR
Sulfate 0.28
Pyritic <0.01
