Prelimer suspended solids can be separated. - ASSBT Proceedings

Note that with the high speed pump the filtrate recovered is nearly doubled when
filtration is ahead of the pump. 1t will also be seen that four times as much susp nded
solids were removed. This is surely strong evidence of degradation of the fragile floc
particles by the shear ofthe high speed centrifugal ptunp. With the variable spe d pump
significant improvement is shown. Still, the filtrate volume is 28% greater before the
pump, and the solids removal is 50 percent greater. The evidence indicates that the
gentlest possible handling ofthe effluent is imperative.
We had one opportunity to check out our theory that, with OUT polymer separation of the
suspended solids at the Prelimer, double carbonation would be unnecessary. We
obtained a large sample ofthe Mainlimer effi uent to 1 st Carb and batch carbonated tl e
sample in the laboratory. As the batch carbonation pro ceded, samples wer removed for
analysis. The pH, Iimesalts. purity. and color was detenn ined for each as shown in the
following Table, Table 3.
TABLE 3
BATCH CARBONATION OF MAfNLIMER EFFLUENT
pH UMESALTS PURITY COLQR
11.9 0. 194 43 L
11 .2 0. 11 ] 93.2 183
10.7 0. 068 92.7 83
10.3 0.064 93.4 91
9.9 0.043 93.2 63
9.4 0.063 93.2 70
Since this is infonnation from only a single laboratory sample, we surely cannot claim
any proof of anything. We can, however say that the data give an indication that we
could indeed eliminate the normal double carbonation. The nonnal 2nd Carb pattern of a
minimum limesalts is indicated, although at a pH of 9.9--higher than the usual 9.2-9.4 or
so. The purity a-ppears to be essentially constant, as it should be with onJy minimal
elimination ofnonsugars. And the color pattern is also about normal. We e en got the
minimal color at minimum limesalts in the test. Hopefully the premise ofthe single
carbonation will soon be resolved at the plant level.
Using assumptions that I felt were reasonable, I made something ofa quick economic
analysis which indicated that, despite the very poor lime waste losses, the periods of
testing may well have been profitable. Obviously, the polymer technology will never be
adopted until good profitability can be demonstrated. 1 would li ke to see some of the
plant people study the economjcs thoroughly. In my opinion tie potential for this
technology is great. It only stands to reason that nonsugars, particularly the fluffy, stick),
ones should be removed from the process stream as quickly as possible. Removal at the
Prelimer is at the first processing step.
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