Hydrothermal Carbonization of Primary Sewage Sludge and Synthetic Faeces: Effect of Reaction Temperature and Time on Filterability

The effect of reaction temperature and time on the filterability of slurries of primary sewage sludge (PS,S) and syuthetic faeces (SO following hydrothermal carbonization (1110 was investigated and optimized using response surface methodology (16.11). Filterability was shown to improve as the treatment tempei-alure and reaction time al which the solids were carbonized was increased. The best filtration results were achieved at the highest temperature (200 degrees C) and longest treatment time (240 min) employed here. The specific cake resistance to filtration of the carbonized solids was found to vary between 5.43 X 10(12) and 2.05 X 10m iii kg(-1) for cold filtration of PSS 1.11 X 10(12) and 3.49 x 10(10) an g(-1) for cold filtration of SF and 3.01 X 10(12) and 3.86 X 10(10) m kg(-1) for hot filtration of SF, and decreased with increasing reaction temperature and time for carbonization. There was no significant differem:e in the specific resistaru:e o f cold and hot filtration for SF. The 1/.5111 models employed here were found to yieltl predictions that were close to the everimental results obtained and should therefore prove useful in designing and optimizing HTC filtration systeans for generating solids for a wide variety of end USCS. (C) 2015 American Institute of Chemical Engineers Fm iron Prog, 34 : 1279-1290, 2015