The Impact of Cold Weather and Temperatures on the Design of Supplemental Carbon Facilities Using Glycerol as a Carbon Source for Biological Nitrogen Removal

Viscosity is an important variable in the design of supplemental carbon storage and feed facilities. The viscosity of glycerol solutions varies significantly with temperature and glycerol concentration. The design of the supplemental carbon facilities has thus far been based on limited published literature values and available vendor viscosity data. The objective of the viscosity testing is to identify the winter viscosities as a function of temperature for several commercially available supplemental carbon sources. Understanding the results of the viscosity tests will lead to identifying design criteria for the supplemental carbon facilities during cold weather operations, and considerations to accommodate a wider range of products to keep viscosities manageable. The results and historical ambient temperature data indicate that low temperatures in New York City (NYC) can result in elevated viscosities and thus excessive headloss and backpressure in the glycerol feed system. Alternative wintertime carbon strategies must be considered to accommodate the adverse impacts of low temperatures on viscosity. Three strategies are presented based on the viscosity analysis of several commercially available glycerol products. One cold weather operation strategy is to maintain the storage temperature above −4°C during cold weather. Another cold weather operation strategy is to dilute the glycerine-based carbon product to 60% wt/wt glycerol when temperatures fall below −4°C, approximately 2 to 3 of the coldest winter months. Lastly, 60% wt/wt glycerol can also be purchased and used when temperatures fall below −4°C.