INVESTIGATING THE ROLE OF PROCESS CONDITIONS IN WASTEWATER SLUDGE ODOR GENERATION

Odor gas production from solids handling processes in wastewater treatment has long been a matter of concern. In this study, the production of malodorous odors from unlimed sludges and biosolids was investigated along with the role of trivalent cations in odor gas generation. The effect of shear and polymer dose on Trimethylamine (TMA) production was also determined. It was found that production of total sulfur odor gases and TMA over time was influenced by the lime dose and the incorporation of lime into sludge. Shear conditions present in belt filter press produced higher quantities of odor gases compared to a vacuum filter. It was determined that odor potential is directly related to the labile protein content in sludge/biosolids. Furthermore, as the Al/Fe ratio increased, the labile proteins were observed to decrease. This indicates that trivalent cations have an important role in binding the proteins thus controlling their bioavailability and hence effecting odor production. This was found true for most sludge irrespective of their liming status and independent of upstream process conditions. Cationic polymers used to condition wastewater sludges are thought to be precursors for TMA production. Proteins contained in sludge may also be associated with odor potential. It is hypothesized that these two components, under conditions of shear, are more likely to cause an increase in odor production from lime stabilized biosolids. In general, TMA production occurs with polymer addition and shear exposure. It was also determined that abiotic polymer degradation to produce TMA either does not happen or the rate constant is so slow that TMA production in this way is insignificant for actual field situations.