Organic pollutant removal versus toxicity reduction in industrial wastewater treatment: the example of wastewater from fluorescent whitening agent production.
Industrial wastewater treatment in the chemical industry aims at eliminating organic contaminants, as these pollutants may be persistent and ecotoxic. In a case study performed in collaboration with the chemical industry, we investigated the removal of a fluorescent whitening agent and its side products in the wastewater-treatment system. Adsorption to activated carbon and biological treatment were simulated in laboratory tests. Algae toxicity tests were performed to quantify the toxicity of the wastewater mixture and of single components. The contaminants identified accounted for up to 82% of the wastewater's total organic carbon (TOC). Adsorption to activated carbon eliminated the TOC and the single contaminants only slightly. Nevertheless, the toxicity of the wastewater decreased by 40%. In contrast, biological treatment reduced the TOC by up to 80%, and the whole effluent toxicity increased. These results indicate that new ecotoxic metabolites were formed during the biological treatment. They also illustrate that mere reduction of the TOC in the wastewater-treatment system is not sufficient for ensuring a reduction of environmental impact. Therefore, simultaneously conducting TOC measurements and toxicity tests, as demonstrated in the current work, is recommended.
Köhler
Annette
A
ETH Zürich, Safety and Environmental Technology Group, 8093 Zürich, Switzerland. annette.koehler@empa.ch
Hellweg
Stefanie
S
Escher
Beate I
BI
Hungerbühler
Konrad
K
D000327:Adsorption; D019149:Bioreactors; D002244:Carbon / Q000302:isolation & purification* / Q000378:metabolism / Q000633:toxicity; D004396:Coloring Agents / Q000302:isolation & purification* / Q000378:metabolism / Q000633:toxicity; D007220:Industrial Waste; D009930:Organic Chemicals / Q000302:isolation & purification* / Q000378:metabolism / Q000633:toxicity; D010084:Oxidation-Reduction; D013783:Textile Industry; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification* / Q000378:metabolism / Q000633:toxicity
D004396:Coloring Agents; D007220:Industrial Waste; D009930:Organic Chemicals; D014874:Water Pollutants, Chemical; D002244:Carbon