Prelimer suspended solids can be separated. - ASSBT Proceedings

TABLE 1
THE EFFECT OF POLYMERS ON SETTLING RATES
Polymer Additions in Parts Per Million
30-2009 30-2009 30-2009 30-2009
(aIQ n~ ) 5 FC3 +1 FC3 +2 Fe3
30-2009
+3 C3
Sludge L vel
Milliliters
450 38 sec 8 sec 11 sec 8 sec 7 sec
400 62 14 l8 12 12
350 87 18 25 . 16 16
300 111 2J
"")
j", 20 20
250 137 24 39 24
")"
L-'
200 26 49 32 30
175 67 46 41
150 29 108 76 71
First note that no untreated settling rate is presented because the floc formation and
characteristics were such that no sludge-supernatant interface could be determined.
Sometimes fairly decent settling rates for the untreated effluent could be measrrred, but
quite often the mixture fail ed to clarify in a reasonable length of time. There are some
interesting things demonstrated by this table. For the sample treated with 2009 alone it
took over two minutes to settle to the 250 mi lliliter level; however, in most clarifiers the
residence time is at least 30 minutes. I have seen 1st Carb settling rates no better than
this. But look at the rates for those samples treated with both the 2009 and the FC3. in
less then two minutes all had settled to the 150 level with the 2009 plus 5 ppm FC3
reaching that level in less than half a min ute. All of the combinations shown in the table
gave excellent settling. Some interesting things show up in the data. For instance, the 2
and 3 ppm FC3 treatments start out better than the 5ppm, but notice that toward the end
the 5ppm level proves best, as would be expected. As mentioned earlier, the turbuJence
from mixing has to subside so that the solid particles, which are going in all directions
when mixed, can start their downward motion. Only a second OT two is involved
initially, and, as fast as the settling proceeds, an error ofone second in taking the read1l1g
is quite possible. The reading at the 175 ml level for the 5ppm treatment is absent,
because in changing from the 50 ml distance to the 25 ml the reading was missed
entirely. These rates are among the best one can expect, and don' t forget that j ulce
quality and effectiveness of plant operation will affect the rates.
We believe that the best information available upon which to j udge the polymer system
with removal of the suspended solids at the Prelimer is that taken at the Worland plant
during the 1997-98 campaign. Two different test periods ere run: Monday (day ending
at 8:00 AM Dec. 9 till Fr iday (day ending Dec. 13, 1997) and Monday (DE Jan 13 ) till
Wednesday (DE Jan 22, 1998). The entire plant stream was treated at the Prelimer with
30 ppm cationic Mafloc 2009 introduced into the 5th cell of their Brieghel-Muller
Prelimer followed by 2-5 ppm Applexi on Flo Cap 3 anionic polymer added to the
Prelimer overflow trough. Each switch from nonna} processing with nonsugar removal
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