WERF Odor Study Phase III: Impacts of Dewatering Processes and Operational Parameters on Production of Odor Causing Compounds

As part of the Water Environment Research Foundation's study on biosolids odors, a series of experiments were performed to examine the effect of dewatering processes on odor generation. In general, samples were collected from full-scale processes that used different dewatering devices to compare side-by-side dewatering equipment. In addition, trials were performed to examine the impact of different centrifuge operational parameters on the generation of odorous compounds (mainly total volatile organic sulfur compounds or TVOSCs). The results showed that belt filter press and rotary press dewatered cakes had much lower odorous compound production than centrifuged cakes. Low solids centrifuges had lower odors than higher solids centrifuges. For centrifuge operating parameters, increasing the torque results in greater TVOSC production in the cake, similarly, reducing the bowl speed reduced the odorant production. Oftentimes, process changes that increase cake solids were associated with greater TVOSC production. The results demonstrate that very large differences in cake odor quality can result with different dewatering processes.