The Production of Charcoal from Bagasse
ROBERT F. McCAULEY Visiting Professor
NATHAN C. BURBANK, JR., Professor
REGINALD H. F. YOUNG, Assistant Professor
School of Public Health
University of Hawaii
Honolulu, Hawaii
PHYSICAL AND CHEMICAL CHARACTERISTICS OF BAGASSE
Bagasse is a solid waste which results from the extraction of sugar from sugar
cane. Sugar is present within the cane stalk as cane juice and extracted by passing the
cane through heavy rollers and shredders to press the liquid fraction from the solid
residue. As the fiber passes through each roller to the next, it is sprinkled with hot
water to dilute the remaining juice and permit its extraction.
Fibrous material discharged from sugar mills after sugar extraction is called
bagasse. The bagasse is usually low in sugar, indicating high extraction efficiency. The
composition of bagasse is not constant and is dependent upon both the cane and
the method of extraction. Wet bagasse is usually 40 to 50 per cent water and 50 to
60 per cent solids. A typical analysis (1) of wet bagasse discharged from the mill
shredders and rollers is shown in Table 1.
TABLE I
Wet Bagasse
Discharged from
Mill Rollers (2)
Water 48.5 Per cent
Fiber 46.5
Sugar 4.0
Ash    1.0
ANALYSIS OF BAGASSE
Dry Fiber
Cellulose.. 50-60 Per cent
Pentosans 20-25
Lignin    10-18
Ash    15-30
Ultimate
Analysis
Dry Bagasse (3)
Carbon . . . 43-47 Per cent
Hydrogen 5.4-6.6
Oxygen    45-49
Ash    1.5-3.0
The moisture content of Hawaiian bagasse is somewhat less than 48 per cent
because of good mill efficiency, averaging about 44 per cent.
Bagasse is physically constituted of two fractions, pith and fiber. Pith often
contains more than 25 per cent pentosans on a dry weight basis. The fibrous fraction
is higher in cellulose and with fibers approximately the same length as hardwood.
Bagasse fibers are higher in ash, hemicellulose and pentosans than wood. They have a
lower lignin and alphacellulose content (2). In general, the chemical characteristics of
bagasse are more similar to hard than to soft wood.
Several potential commercial uses for bagasse require separation of the fiber
and pith. The Rietz Disintegrator has been successfully used for wet depithing (2).
When separated from pith, fiber has been used for the manufacture of paper, corru-
-551.