ANAEROBIC TREATMENT APPLICATIONS AND FUNDAMENTALS - SUBSTRATE-SPECIFICITY DURING PHASE-SEPARATION

The effect of phase separation on anaerobic biodegradation was evaluat ed in terms of thermodynamic principles. Individual components of comm on wastewaters were considered, and results indicate that the response of different substrates to phase-separated anaerobic treatment is div erse. A key element is the response of soluble substrates to acidifica tion when syntrophic relationships are eliminated and biological react ions that require syntrophic relationships are altered. The acidificat ion of carbohydrates and some proteins is thermodynamically favorable. In contrast, the acidification of fatty acids and aromatics is not th ermodynamically favorable unless a sink for reducing equivalents is av ailable. Reported data are consistent with this analysis and phase sep aration has been observed to enhance the treatment of carbohydrate was tewaters. In addition. the potential for detoxification of specific in hibitory compounds under acidifying conditions has been observed. Whet her or not treatment of certain substrates will be enhanced by phase s eparation should be considered in the choice of reactor design, recogn izing that various reactor designs exhibit different degrees of phase separation. This paper presents an overview on how phase-separated tre atment affects the biodegradation of specific substrates and relates t his to the selection of reactor designs.