Dewatering Characteristics of Cambi Thermal Hydrolysis Biosolids: Centrifuges vs. BFPs

A study was performed to assess the differences in belt filter press (BFP) and centrifuge dewatering of the Cambi Thermal Hydrolysis Process (THP) sludges. The THP processes heats the sludge to temperatures of 150-165 °C prior to anaerobic digestion which helps increase the rate and extent of digestion. Site visits to existing THP plants and several pilot trials showed that BFP and centrifuges produce similar cake solids, both able to achieve cake solids greater than 30%. In addition, the BFP performance in terms of high cake solids and high solids capture was achieved over a wide range of solids loading rates, from 200–1200 kg/hr per meter of belt width. Cakes produced from BFP dewatering were also less odorous as measured by organic sulfur concentrations and odor panels when compared to centrifuge dewatered cake. The results suggest that for THP sludges, BFP dewatering provides equivalent cake solids and capture while minimizing the risks associated with poor cake quality that have been reported with centrifuge dewatering.