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

The relative environmental quality of laboratory prepared spent bleach ing effluents from various bleaching technologies was evaluated. The e ffects of the various effluents on Ceriodaphnia reproduction followed the order: OZEP > OQP > (C90 + d10) E almost-equal-to (D50c50)E > D100 E > OD100E, while the effects on fathead minnow growth could be ranked as follows: (C90 + d10)E almost-equal-to (D50c50) E almost-equal-to D 100E > OZEP > OQP > OD100E. For the chronic sublethal effects studied, whether the bleaching was performed with chlorine-containing compound s or under totally chlorine free conditions, the least toxic effluent on a consistent basis was that bleached with the OD100E sequence.