Effect of selected textile effluents on activated sludge nitrification process.

In this study, a recently developed methodology for the assessment of the inhibitory effect on nitrifying biomass was applied to several textile effluents from productive processes. Effluents are classified according to the degree of inhibition as EC50 (concentration producing 50% nitrification inhibition); the investigated textile effluents showed a wide range of EC50 ranging from 20 ml gVSS-1 (83 ml l-1) to values above 100 ml gVSS-1 (300 ml l-1) for effluents produced by rinsing phases. Taking into account biodegradability and toxicity evaluations, most of the effluents showed a good treatability in conventional biological wastewater treatment plant. On the other hand three textile effluents showed significant toxic effects towards nitrifying biomass. In any case, the proposed procedure represents an efficient tool to prevent treatment failures due to toxic discharges.