ESEL Paper Review_201303 24

By Hong Guo

Mail: hongguo@gist.ac.kr

Phone: (+82) (0)10 82276568

1, Title and Author

Title: A method for characterizing the complete settling process of active sludge

Journal: Water Research

Authors:

Daijun Zhanga,b,*, zhenliang Lia, Peili Lua, Tian zhanga, Danyu Xua

a Department of Environmental Science, Campus A, Chongqing University, Chongqing 40030, China

b Kay Laboratory for the Resource갽 Exploitation and Environmental disaster Control Engineering in Southwest China, State Ministry of Education, Chongqing university, Chongqing 400030,China

2. Summary of Paper

In this paper, the authors developed a theoretical equation for determining the critical point when the compression settling stage commences and a new velocity function for the compression settling were deduced from the model. By combining the new model and the conservation of mass, it was proved that the Vesilind function was also capable of describing the compression settling velocity on condition that the appropriate parameters were estimated.

3. Results

. Dividing the complete settling process of activated sludge into the zone settling and compression settling stages, and describing them by the Vesilind function with different parameter sets was more reasonable for charactering the complete settling process of activated sludge.

. The author developed the equation for estimating Time (when the compression settling commences) accurately enough, and would have the exact root if the parameters were appropriate.

. The value from the equation could be comparable but the former are always smaller than the latter, because it does not take account of the lag and transition stages of settling process.

. ........,..=.........=....(..+....)?....(...+....), compression-settling velocity is related to three parameters, the settling time, the initial settling condition and the sludge characteristics.

. The function describes the relation between the velocity and the time in the compression settling process, and the relation between the velocity and the sludge concentration as well

. The relation between the velocity and the sludge concentration in the compression settling stage is similar to that in the zone settling stages.

Moreover, both the velocities and their variability rates decrease as the

sludge concentration increases.

. If the feed sludge concentration in SSTs is not too low, compression

settling process is a very important stages. The accurate description of

compression settling is necessary to predict the sludge profile in SSTs and

return sludge concentration.

4. Contribution:

The paper developed a model, which could describes the compression settling

process of activated sludge. In addition, a theoretical equation for determining

the critical point when the compression settling stage commences was deuced

from the model. the author describe mathematical model to the complicated

settling process. It could be applied to the describe the phenomena inside the

the sedimentation tank

5. Author information:

Email: andy.chan@nottingham.edu.my