EVALUATION OF ION EXCHANGE TECHNOLOGY
FOR TOXIC AND NONCONVENTIONAL POLLUTANT REDUCTION
IN BLEACH PLANT EFFLUENTS
James H. Fitch, Jr., Environmental Engineer
E. C. Jordan Co.
Portland, Maine 04112
The wastes resulting from bleach plant operations in the pulp, paper and paperboard industry characteristically contribute color, chemical oxygen demand (COD) and toxicity to
the effluent wastestreams discharged. The U.S. Environmental Protection Agency Effluent
Guidelines Division has evaluated the applicability of several new treatment technologies to
reduce the pollutional impacts of bleach plant effluents. These evaluations included a study
of ion exchange technology.
A literature search was conducted to determine the state-of-the-art of ion exchange treatment of complex waste streams and to assess the technology's effectiveness in reducing toxic
and nonconventional pollutant loads. The literature sources indicated that, with pH adjustment and pretreatment, weakly basic ion exchange resins are superior in treating pulp, paper
and paperboard bleach plant effluents.
Three ion exchange design schemes have been developed for treating bleach plant effluents: the Dow process, the Rohm and Haas process, and the Billerud nonpolluting bleach
plant concept. Though all three processes are designed to minimize chemical use and pollutant disposal costs, only the Billerud concept has been applied to the pulp, paper and
paperboard industry on a full-scale basis.
The Billerud system is a patented ion exchange technology instituted at the Billerud
Uddeholm AB mill in Skoghall, Sweden. The mill employs dissolving sulfite, kraft and
thermomechanical pulping processes to produce market pulp, bleached specialty grades, unbleached kraft sack paper, folding boxboard and a variety of other products. The plant is
located on and discharges into a lake which can assimilate COD but not color. The Swedish
government has therefore limited the plant's color discharge to 10% of initial color load
(90% removal required).
A full-scale batch ion exchange system was installed in 1973 to allow the plant to meet its
color limitation. In addition to reducing color discharges by approximately 90%, the system
proved capable of removing other pollutants including chlorinated phenols (95-99%), chlorinated guaiacols (80-90%), and COD (70%).
A continuously operating, microprocessor-controlled pilot plant ion exchange system was
constructed in 1976 based on the nonpolluting bleach plant concept, which is an expansion
of the color removal concept.
Both the batch and pilot plant systems installed at the Billerud plant were sampled during
this evaluation to assess actual operating parameters, removal efficiencies, and associated
problems and costs.
DESCRIPTION OF THE BATCH PLANT
The batch plant consists of 20 mesh screens (prefilters), a storage tank, sand filters, a
second storage tank and three ion exchange columns. Each column has a volume of 60 m
and contains 13 1 m3 of resin. Flow through the system is approximately five bed volumes
per hour and the cycle time (treatment time between changes in flow scheme) is three hours.
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