A LABORATORY ASSESSMENT OF THE ENVIRONMENTAL-QUALITY OF ALTERNATIVE PULP BLEACHING EFFLUENTS

The relative environmental quality of laboratory prepared spent bleaching effluents from various bleaching technologies was evaluated. The effects of the various effluents on Ceriodaphnia reproduction followed the order: OZEP > OQP > (C90 + d10) E almost-equal-to (D50c50)E > D100E > OD100E, while the effects on fathead minnow growth could be ranked as follows: (C90 + d10)E almost-equal-to (D50c50) E almost-equal-to D100E > OZEP > OQP > OD100E. For the chronic sublethal effects studied, whether the bleaching was performed with chlorine-containing compounds or under totally chlorine free conditions, the least toxic effluent on a consistent basis was that bleached with the OD100E sequence.