Whey treatment in ASBR: influence of feeding strategy

Author(s)

Leonardo Henrique Soares Damasceno

• Document type: Master's Dissertation
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD)
• Defense date: 2004-04-16

Examining board members

José Alberto Domingues Rodrigues; Eugenio Foresti; Hugo Moreira Soares

• Advisor: José Alberto Domingues Rodrigues

Abstract

The performance of an anaerobic sequencing batch biofilm reactor (ASBBR) treating cheese whey was evaluated when subjected to different feeding strategies and volumetric organic loads (VOL). The reactor operated under mechanical stirring provided by helix impellers at rotor speed of 500 rpm. A volume of 2 l was fed per cycle with 1 l of residual volume, totalizing 3 l. Reconstituted dehydrated cheese whey was used as substrate. NaHCO3 was supplemented at a ratio of 50% NaHCO3/COD. The following VOLs were tested: 2, 4, 8 and 12 gCOD/l.d. For 8-h cycles and each value of VOL three feed strategies were tested: (a) batch operation with 8-h cycle; (b) 2-h fed-batch operation; and (c) 4-h fed-batch. In the VOL of 2 gCOD/l.d, organic matter conversions as COD were 92, 96 and 91%, for feeding strategies (a), (b) and (c), respectively. For the VOL of 4 gCOD/l.d, performance values were 94, 97 and 93%, respectively. For the VOL of 8 gCOD/l.d there was a reduction in conversion efficiency to 84, 85 and 86%, respectively. The increase of VOL to 12 gCOD/l.d resulted in the reduction in efficiency of 78, 73 and 81%, respectively. The profiles of total volatile acids concentration obtained during the cycles showed that despite its gradual increase with the increasingly filling time, no significant differences were detected in terms of maximum values. Reduction in proprionic acid concentration along the cycle were observed as consequence of the increase of the filling time. Thus, for VOL of 2 and 4 gCOD/l.d feeding strategy (b) provided higher conversion efficiency and operation stability. This behavior was similar to that observed for the feeding strategy (c) at the VOL of 8 and 12 gCOD/l.d. (AU)