Changes in Ceriodaphnia and Fathead Minnow Life Cycle Test Results Associated With Modified Pulping and Bleaching Practices, 1995 Process & Product Quality Conference Proceedings

D.L. Borton Aquatic

W.R. Streblow

T.M. Bousquet

National Council of the Paper Industry for Air and Stream Improvement

Fathead minnow (Pimephales promelas) and Ceriodaphnia life cycle tests as well as fathead minnow growth tests were completed using biologically treated effluent from a bleached kraft pulp mill before and after pulping and bleaching process changes. The “preconversion” processes did not include oxygen delignification (OD) and only molecular chlorine(Cl2 ) was used in the first bleaching stage. The “postconversion” process added OD and substituted chlorine dioxide(CIO2 ) for Cl2 to produce bleached pulp using an elemental chlorine free (ECF) process. Several parameters such as COD, BOD, TSS, and AOX were significantly decreased after conversion as were the concentrations of color, conductivity, fatty acids and resin acids. Chlorophenols, cloroguiacols and chlorocatecols were all reduced to below detection limits. Average IC25 s of 7-d Ceriodaphnia tests (-50%) and fathead minnow tests (>100%) were not changed significantly alter conversion. The average IC25 s for fathead minnow growth during 28 day tests was increased significantly from 18% v/v effluent during preconversion studies to >100% effluent during postconversion studies. The average IC25 for eggs/female of 4 tests using the preconversion effluent was 11% effluent and the average of 4 IC25 s with the postconversion effluent was 60% effluent which was significantly greater. Since components from both the pulping process (fatty and resin acids, COD, BOD) and the bleaching process (chlorinated organics, BOD, COD) were reduced after the process conversions, the specific components or sources of the reduced effect on growth and reproduction of fathead minnows cannot be determined by these tests.