Experimental basis for the hydrolysis of slowly biodegradable substrate indifferent wastewaters

The conceptual framework for the hydrolysis of slowly biodegradable substra te is reviewed by means of a model evaluation of the OUR profiles resulting from different rate expressions and the merit of each proposed mechanism i s evaluated on the basis of experimental results. The sensitivity of the ex perimental evaluation technique, with specific emphasis on parameter identi fiability, is investigated in assessing the values of the maximum specific hydrolysis rate, k(h) and the half-saturation coefficient for hydrolysis, K -x. The results of extensive studies for the experimental assessment of the hydrolysis rate coefficients for both domestic sewage and a number of indu strial wastewaters are summarized. Furthermore, the question of organics wi th different hydrolysis rates is addressed by identifying readily and slowl y hydrolyzable COD fractions. Dual hydrolysis approach is evaluated in term s of its implication on process kinetics and especially on the assessment o f the endogenous decay mechanism. (C) 1999 IAWQ Published by Elsevier Scien ce Ltd. All rights reserved.