Effluent Quality Characteristics at North American Kraft Mills Employing Complete Substitution Bleaching, 1997 Pulping Conference Proceedings

USEPA’s 1993 proposal to revise effluent limitations guidelines for the pulp and paper industry sparked a significant industry-sponsored effort to increase the amount of data describing the characteristics of effluents discharged by kraft mills using complete chlorine dioxide substitution bleaching. This paper presents a summary of these data generated by, or made available to, NCASI. Data comparable to the proposed effluent guidelines limitations shows that complete substitution bleaching effluents do not normally contain measurable levels of 2,3,7,8-TCDD and rarely contain measurable levels of 2,3,7,8-TCDF or highly substituted chlorinated phenolic compounds. Chloroform levels measured in bleaching effluents range from 0.16 to 4.8 g/t and represent only a fraction of the total chloroform generated during bleaching. Available data describing the levels of AOX and COD in biologically treated effluents suggest that the use of extended and/or oxygen delignification can reduce effluent loads for these parameters.