Entwicklung von Verfahrensgrundlagen zur biologischen Stickstoff-Eliminierung aus Betriebsabwaessern der Metallverarbeitung. T. A und Abschlussbericht

Wastewaters from electrochemical deburring of gear units and axles (EC-Water) and permeates obtained by ultrafiltration of coolants were treated in fixed bed reactors. In the denitrification and the subsequent aerobic stage 75% of the DOC were eliminated. Experiments to oxidise the residual DOC chemically showed that such a treatment step will be not economical. Nitrification was only possible if an pretreated industrial wastewater was dosed to the other wastewater streams resulting in a dilution of the permeate of 1/5. By treatment with pre-denitrification 90% of DOC and N_t_o_t_a_l were eliminated. By sludge-returnment higher loading rates could be obtained. The COD of the effluent was often greater than 300 mg O_2/l. The SVI was not greater than 130 ml/g. Automatic regulation of the C/N-ratio is till now not possible because of lacking of a reliable method to determine nitrogen online. The TN_b is an unreliable parameter for online process regulation. Inhibitors of nitrification are common ingredients of the coolants. In case of boron nitrification was possible up to a concentration of 700 mg/l B after a long adaption-time. In boronfree permeates of fresh coolants nitrification couldn't be established. 15% of DOC and organic nitrogen were persistent. Input of persistent DOC by sources of pollution like oil and washwaters seem to be neglectible. Jodpropinylbutylcarbamate (a fungizide) and Tolyltriazole, an ingredient of the emulsions to prevent dissolving of non-ferrous metals, were analysed for its inhibitory quality on microbial activity. (orig.)Available from TIB Hannover: F99B929+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman