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Toxicity of conventional, elemental chlorine‐free, and totally chlorine‐free kraft‐pulp bleaching effluents assessed by shortterm lethal and sublethal bioassays
Author(s) -
Tarkpea Maria,
Eklund Britta,
Linde Margareta,
Bengtsson BengtErik
Publication year - 1999
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620181115
Subject(s) - softwood , effluent , hardwood , kraft process , pulp (tooth) , bioassay , chlorine , acute toxicity , chemistry , kraft paper , chlorine dioxide , biocide , pulp and paper industry , toxicity , environmental chemistry , botany , biology , environmental engineering , environmental science , ecology , organic chemistry , medicine , pathology , engineering
The toxicity of nine effluents from Swedish kraft‐pulp mills using conventional, elemental chlorine‐free (ECF) and totally chlorine‐free (TCF) bleaching processes was studied. Effluents represented six different processes: conventional‐softwood 30% ClO 2 ; ECF‐softwood; TCF‐hardwood, for which all the samples were taken before and after secondary treatment; conventional‐softwood 8% ClO 2 ; TCF‐softwood O 3 /H 2 O 2 ; and TCF‐softwood H 2 O 2 . Comparison of effluents, which had not undergone secondary treatment, suggested that those from mills using conventional bleached pulp were the most toxic, with toxic emission factors (TEF) ≈ 1,000 according to the Microtox® test (AZUR Environmental, Carlsbad, CA, USA). In the acute Nitocra spinipes test, the conventional‐softwood 8% ClO 2 and the ECF‐softwood effluents before secondary treatment were the most toxic, with TEF ≈ 700. In the reproduction test, N. spinipes was two to three times more sensitive than in the lethal test. The species most sensitive to the effluents investigated was the macroalga Ceramium strictum , with TEF values up to 3,000. The conventional effluent using a substitution of 8% ClO 2 was the most toxic, and the TCF effluents were the least toxic. Degradation treatment of the ECF and TCF effluents for 28 d in the laboratory did not eliminate acute lethal effects on N. spinipes and the Microtox bacterium.