Browsing by Author "Houghton, Jennifer I."
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Item Open Access Effect of influent organic content on digested sludge extracellular polymer content and dewaterability(Elsevier, 2002-08) Houghton, Jennifer I.; Stephenson, TomThe organic composition of the feed sludge to six laboratory-scale anaerobic digesters was adjusted by substituting a proportion of the primary sludge for glucose or propionic acid solution. Substitution with glucose caused an increase in the microbial extracellular polymer (ECP) content of the digested sludge, which altered the particle size distribution of the sludge and made the sludge more difficult to dewater. Substitution with propionic acid gave similar results to the control. The relationship between the digested sludge extracted ECP yield and sludge filtrability determined using the capillary suction time test was significant at the P ¼ 0:01 level. The level of ECP for optimum sludge dewaterability was calculated as 17.2mg g-1 SS. The protein and carbohydrate composition of the extracted polymer did not appear to affect the sludge dewaterability. Results present will allow predictions to be made into the effect that changes in the influent sewage composition has on essential downstream processes.Item Open Access Off-line particle size analysis of digested sludge.(Elsevier Science B.V., Amsterdam., 2002-11-01T00:00:00Z) Houghton, Jennifer I.; Stephenson, TomParticle size analysis was carried out on six samples of digested sludge using laser diffraction. The digested sludge was produced in laboratory-scale reactors under different feed regimes based on a mixture of primary and waste activated sludge (WAS). Laser diffraction proved capable of providing rapid, reproducible results of the particle size distribution of each sample, and highlighted differences between the different treatments. An increase in the level of WAS in the digester feed sludge led to a shift in the size distribution, with a decrease in the number of smaller sized particles.