Lit. Review for Upflow Velocities

[ananya-gangadhar]

@IanCullings , @ninablahut , @cjmsmith , @Simarkohli24 go ahead and post the links to all the cool papers you found on this thread. If possible, include a short 1-2 sentence summary of what you found interesting about the paper.

[Simarkohli24]

https://www.sciencedirect.com/science/article/pii/S0960852406001738

• Sludge present in the reactor is composed of microorganisms that naturally form granules of 0.5–5 mm diameter that exhibit high settling velocity
• Although, in general, development of bioparticles on and above 0.5 mm size has been considered as granules by many researchers (Wang et al., 2004, Show et al., 2004, Bellouti et al., 1997, Yan and Tay, 1997), however, few have considered 0.16 mm or less as granules (Tiwari et al., 2005, Chou and Huang, 2005, Pevere et al., 2006, Lalit et al., 1997).
• The upflow velocity in full scale UASB reactor was generally in the range of 1.5–1.75 m/h under peak flow conditions and usually kept below 2.0 m/h (Hulshoff et al., 2004).
• 
• Based on the sedimentation theory it could be said that the minimum size of the granules required for better retention of sludge inside UASB reactor varied with the specific gravity of the sludge.

[Simarkohli24]

https://link.springer.com/content/pdf/10.1007%2FBF00872193.pdf

• “As a matter of fact in their experiments with the anaerobic filter Young & McCarty (1969) already recognized the ability of anaerobic sludge to form very well settleable aggregates. They stated: 'The rolling action of the rising gas bubbles caused the sludge particle to take a granular form. These granules were as large as 3.1 mm in diameter and settle readily.' In AF-experiments with potato starch wastewater and methanol solutions we made similar observations (Lettinga et al. 1972, 1979). Like the researchers in South Africa, the group of McCarty was unable to continue the work on anaerobic wastewater treatment due to lack of funding. “
• A non or only partially acidified sucrose feed (less than 70%) initiates the growth of a fragile type of granular sludge with a layered structure. This was also found by Fang (1994) and Thaveesri et al. (1994). The accumulation of biogas within and around the aggregates (e.g. between the layers) causes the flotation of the grains. Moreover, the growth of dispersed acidogenic bacteria enhances granular sludge flotation and also leads to an excessive expansion of the sludge bed, consequently to a poorer sludge retention in the system.

[ananya-gangadhar]

Influence of Pulsation on the Startup of a UASB Reactor

This paper talks about how using pulse flow through a lab-scale UASB reactor improves treatment efficiency, biogas production and overall reactor performance.