Activated sludge respirometry to assess solar detoxification of a metal finishing effluent

• Published in: Journal of hazardous materials Vol. 153; no. 3; pp. 905 - 910
• Main Authors: Santos-Juanes, L., Amat, A.M., Arques, A., Bernabeu, A., Silvestre, M., Vicente, R., Añó, E.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 30-05-2008; Elsevier
• Subjects: Activated sludge; Aliivibrio fischeri - drug effects; Aliivibrio fischeri - metabolism; Applied sciences; Catalysis; Catalytic reactions; Chemical engineering; Chemistry; Copper - chemistry; Copper - radiation effects; Cyanide; Cyanides - chemistry; Cyanides - radiation effects; Detoxification; Exact sciences and technology; General and physical chemistry; General purification processes; Hydrogen Peroxide - chemistry; Industrial Waste; Luminescence; Metal finishing effluents; Metallurgy; Oxidants - chemistry; Oxygen - metabolism; Pollution; Reactors; Sewage; Sunlight; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Titanium - chemistry; Vibrio fischeri; Waste Disposal, Fluid - methods; Wastewaters; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - radiation effects; Water treatment and pollution; Sunlight; Metal finishing effluents; Cyanide; Activated sludge; Detoxification; Hydrogen peroxide; Toxicity; Respirometry; Pilot plant scale; Biological purification; Oxidation; Aqueous solution; Waste water purification; Titanium oxide; Solar radiation; Catalyst
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2007.09.033

Inhibition of the respiration of activated sludge has been tested as a convenient method to estimate toxicity of aqueous solutions containing copper and cyanide, such as metal finishing effluents; according to this method, an EC
50 of 0.5
mg/l was determined for CN
− and 3.0
mg/l for copper. Solar detoxification of cyanide-containing solutions was studied using TiO
2, but this process was unfavourable because of the inhibitory role that plays the copper ions present in real effluents on the oxidation of cyanide. On the other hand, the oxidative effect of hydrogen peroxide was greatly enhanced by Cu
2+ and solar irradiation, as complete elimination of free and complexed cyanide could be accomplished, together with precipitation of copper, in experiments carried out at pilot plant scale with real metal finishing effluents. Under these conditions, total detoxification was achieved according to respirometric measurements although some remaining toxicity was determined by more sensitive
Vibrio fischeri luminescent assay.