Full Scale Application of a Novel Sludge Ozonation Process for Achieving 80% Excess Sludge Reduction at a 7 MGD Municipal Wastewater Plant

Ozone induced lysis has been established to be an effective method for reducing excess sludge generation in the activated sludge process (WERF, 2004). Although sludge ozonation in lab scale tests have tended to yield economic dosage rates in the regime of ≤ 0.1 kg O3/kg SS removed, previous attempts to extend the approach to commercial scale installations have resulted in non-economical ozone dosage levels (Sievers et al, 2004; Yasui et al, 1996; Kobayashi et al, 2001; Sakai et al, 1997), requiring as much as 0.35 Kg O3 per kg SS removed (See Table 1).In this paper, we discuss a novel approach to sludge ozonation and the essential scaling factors that permit a successful extension of bench scale results obtained using this approach to commercial scale applications in the field. We also report on the results of full scale tests carried out at a 7 MGD wastewater treatment operation treating about 22,000 Lbs of COD per day which has been in operation since May 2006. A cost effective Ozone consumption value of 0.07 kgs O3/kg SS reduced was attained in the field, demonstrating the successful translation of bench scale type results to field applications using the Praxair approach.