EFFECTS OF PULP MILL POLLUTION ON OYSTERS 
127 
substances in the liquor have been investigated from the standpoint of manufacture 
of commercial alcohol, which is often carried on in Europe. According to Suter- 
meister (1929, p. 234), Krause made the following determinations for liquor from 
autumn-cut wood treated by the Ritter-Kellner process; the results are expressed 
as percentage: Furfural, 0.02; pentosans, 0.29; hexosans, 0.49; total sugars, 1.47; 
pentoses, 0.41; mannose, 0.48; levulose, 0.25; galactose, 0.21; and dextrose, trace. 
Sutermeister (1929, p. 233) summarized a work by Walker as follows: 
“Among the constituents present he mentions sulphur dioxide, sulphur trioxide, free sulphur, 
calcium and magnesium lignin sulphonates, pentoses and pentosans, mannose, dextrose, galactose, 
free furfural, traces of vanillin or vanillinlike body and small quantities of terpenelike substances.” 
Citing another work, Sutermeister wrote: “Hoenig claims that no organic acids except formic and 
acetic are present and that the ratio of these is 1: 1.56. He finds 2.15 to 9.08 grams of volatile acid 
per liter.” Further (Sutermeister, p. 235); “The waste liquor, according to Walker, yields bromi- 
nated and chlorinated products; it contains active carbonyl and methyl groups and is a strong re- 
ducing agent.” Methyl alcohol, acetone, aldehyde, acetic and formic acids, and a brown oil, part 
of which is cymene, were found in condensed digester vapors by Bergstrom, according to Sutermeister. 
The same author stated that 8 to 10 kilograms of methyl alcohol are produced per ton of pulp. 
Sutermeister (p. 241) stated: “Other substances which it has been proposed to recover 'from the 
waste liquor are antiseptic materials, calcium sulphate, calcium sulphite, coniferin, cymol, acetic 
acid, furfural, levulinic acid, oxalic acid, sulphur, turpentine, lignorosin, vanillin, etc.” 
In addition to the wide variety of substances mentioned above, the liquor 
contains all of the inorganic components of the wood. These would be in rela- 
tively small amounts, but might be of some significance with regard to aquatic animals. 
These analyses appear not to indicate definitely any particularly toxic substances 
which might be expected to exert an unfavorable influence upon aquatic life. How- 
ever, the wide variety of substances present suggests the possibility that many other 
compounds may be in the liquor in small amounts which would be difficult to detect 
chemically. It has been stated that workmen in sulphite m ills often drink the liquor 
for its laxative effect, which indicates that it certainly is not a violent poison to man. 
Usually pure digester liquor is not dumped into the bodies of water on which 
mills are located. In “blowing” a digester and separating the pulp from the waste 
liquor enough water is used to reduce the specific gravity of the liquor from 1.05 
to between 1.01 and 1.02. Just after a “blow” the liquor is. likely to be of high 
specific gravity, which is reduced in the liquor which follows by dilution. Such 
heavy liquor on entering a turbulent stream is thoroughly diluted, but if it enters a 
relatively still body of water would be expected to sink to the bottom. 
Because of its great excess of sulphurous acid, the liquor is highly acid, a char- 
acteristic which is not conducive to favorable aquatic conditions. However, in the 
case of salt water in particular, the acidity does not last long, partly because of direct 
neutralization and partly due to loss of sulphur dioxide into the air. 
In addition to the liquor, there is a considerable quantity of pulp fiber too small 
to be held in the separators, which must be disposed of as waste. Typically, this 
settles to the bottom of the body of water into which it is thrown and is very slowly 
decomposed. This is an important polluting material in some places, especially in 
streams, where it may interfere with the feeding and breeding of fish. The bleach 
fluid, containing chlorine compounds primarily, is also a constituent of the wastes 
from sulphite mills. 
In some cases the waste liquor is treated to neutralize acidity by passing it over 
limestone before allowing it to go into the water. Running the liquor into a pond 
or settling basin from which it flows into the river has been found advantageous. 
