Section 3.  PAPER WASTES
KRAFT MILL EFFLUENT COLOR REMOVAL
BY ULTRAFILTRATION
Henry A. Fremont, Associate Director
Champion International
Hamdton, Ohio 45020
Myles H. Kleper, Manager
Abxor, Inc.
Wilmington, Massachusetts 01887
INTRODUCTION
Wastewater discharges from integrated kraft mdls are typicady 30,000 gal/ton (125 m3/metric
ton) of pulp produced. The suspended solids and BOD loadings of these wastewaters can
adequately be reduced by conventional treatment processes. Color bodies found in pulp and
paper mdl wastes are, however, resistant to biological degradation and require new treatment
techniques for removal.
Processes developed for color removal include chemical precipitation [1-10], both Ume
precipitation and alum precipitation, adsorption [11-14], oxidation [15-18] and reverse
osmosis and ultrafdtration [19-29]. Also, rapid infdtration [30] involving percolation of the
effluent through the ground and reduction of effluent color by modification of pulping and
bleaching sequences have been demonstrated.
This chapter presents the final phase of a multiyear field demonstration of ultrafdtration
for color removal conducted at Champion International's Canton, North Carolina, mdl.
Major Color Producing Streams
Segration of mdl waste streams is often practiced, and it is likely that segration of wastes
by color content wdl eventuady be required for adequate waste treatment. For example, in
Champion's North Carodna Mdl, about 60% of the total mdl color effluent is present in
about 1 to 2 MGD (3790 to 7580 m3/day) of the pine bleachery first-stage caustic extraction fdtrate. This flow amounts to about 2 to 5% of the total mdl effluent, yet removal
of color from this stream could reduce total effluent color by 60%.
The second most important controllable source of color in a kraft mdl is the pulp washing
decker effluent. This waste stream is present in all pulp mdls, whde the pine caustic extraction fdtrate is found only in mdls producing bleached pulp. At the North Carolina mdl,
approximately 2 MGD (7580 m3/day) of mixed pine and hardwood decker effluents are currently discharged. This waste contributes about 20% of the total mdl effluent color.
In this program, it was decided to primarily study the pine bleachery caustic extraction
fdtrate as the feed to be processed. It constitutes the major color contributor in a kraft pulp
mid system and all previous studies have taught that the pulp washing decker effluents performed in a simdar manner as regards membrane flux but with even more effective color
rejection.
Program Background and Overview
The initial (1970-1973) EPA-sponsored study [31] on the use of ultrafdtration processes
to control kraft mdl effluent color presented a number of recommendations for subsequent
work. In that study, the technical feasibility and economic promise of ultrafdtration was
demonstrated. The major recommendations emphasized the need for studies to improve and
verify the economic bases for the process as new membrane capabdities were developed.
Studies conducted subsequent to 1973 demonstrated that the development of non-
cellulosic membranes by the industry was at a point that promising noncellulosic membranes
were becoming commercially avadable and would be of value in this application.
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