DETERMINATION OF THE IMPACT OF TOXIC INFLOWS ON THE PERFORMANCE OF ACTIVATED-SLUDGE BY WASTE-WATER CHARACTERIZATION

A rational approach for the design of the activated sludge process bas ed on wastewater and biomass characterization techniques as applied to the upgrading of the treatment plant of Volos, a city in the central part of Greece, is presented. The study investigates possible nitrific ation inhibition and carbon inadequacy, due to high salinity, industri al inflows and pre-precipitation by iron salts. The experimentation wa s carried out by means of batch Ammonium Uptake Rate (AUR) and Nitrate s Uptake Rate (NUR) tests. The results show that within the studied ra nge, 900-4000 mg l(-1), chlorides did not inhibit nitrification. Contr ary to this, the industrial wastewater entering the plant was found to be toxic. With the existing 1:15 ratio of industrial to total wastewa ter flow a 50% inhibition to the nitrification process was observed, w hich is higher than the 25-30% inhibition caused by typical domestic s ewage. Industrial contributions exceeding 20% resulted in complete inh ibition of nitrification. With respect to denitrification it was found that the industrial wastewater provided a suitable source of carbon, without any adverse effects on denitrification. Pre-precipitation remo ved about 25% of the filtered COD, thus reducing the amount of nitrate s which could be rapidly denitrified. Design of the biological reactor s on the basis of the findings indicate that a significant under-desig n may result if typical nitrification and denitrification rates obtain ed from the literature and practice concerning typical domestic sewage are adopted. (C) 1997 IAWQ. Published by Elsevier Science Ltd.