Abstract
The loss of granular sludge and acidification of sludge are common problems in highly efficient anaerobic reactors in operation at present, which results in that the reactors cannot reach the design COD removal rates. The problems must be solved for the widespread use of the highly efficient anaerobic reactors. There are many different studies on the formation and loss of granular sludge in an anaerobic reactor, however, the researchers ignore the effects of the gas-producing and biogas-off process of granular sludge on the formation mechanism of granular sludge. The sedimentation and buoyancy phenomena of the granular sludge cultured by self-made transparent reactor were observed in the lab and their relative velocities were measured by photos. Granular sludge and their biogas are coexistent, that is, any size particles of granular sludge can form high floating speed when granular sludge particles contain a lot of bubbles and the granular sludge particles can precipitate well when the air bubbles of granular sludge particles are released in time. So the water test on the sedimentation rate of granular sludge is insufficient. Unified consideration of granular sludge and biogas is beneficial to solve the loss of granular sludge and acidation of sludge in anaerobic reactors and to ensure the normal operation of anaerobic reactors. The biogas-off of biogas produced by anaerobic sludge has essential effects on the granulation of granular sludge. It is conducive to highly efficient anaerobic reactors and three phase separator to reconstruct.
Highlights
There are two focal problems in the practice operation of Up-flow Anaerobic Sludge Blanket and internal circulation reactors
One is that granular sludge is difficult to form in a reactor and it’s operation depends on the flocculated sludge; the other is that the loss of granular sludge and acidification of sludge lead to decrease organic removal rate
In order to reflect the effect of air bubbles on granular sludge, the 26 s mobile phone video was recorded in the condition of the shooting height 10~16 cm of mobile phone
Summary
There are two focal problems in the practice operation of Up-flow Anaerobic Sludge Blanket and internal circulation reactors. The problem of the loss of granular sludge has caused widely concern, for example, gas tunnel was obstructed by extracellular polymer substances (EPSs) which led to the decreasing relative density and the floatation of granules [1], granular sludge with hydrophobic surface has strong adhesion with gas such as CH4, air bubbles cause the loss of granular sludge, the richer protein substrate is, the greater the loss of granular sludge is [2], the more complex the organic substrate is, the easier the flotation of sludge is [3], excessive hydraulic velocity caused the disintegration and the loss of granular sludge [4], the granular sludge had good sedimentation rate will have the loss of granular sludge if biogas will not be separated from granular sludge [5], the relative density of granular sludge with a particle size of 1.0-2.5 mm is larger than 1, while the relative density of smaller and the larger hollow granular sludge is less than 1 which is easy to float up and wash out of the reactor [6]. The relationship between granular sludge and anaerobic biogas was further studied by experiment and observation in the paper
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
