Sequencing Batch Reactor (SBR) is a single vessel reactor which operates in time or it is operated for different batches with varying conditions. 

On the other hand, a semi-continuous reactor has a certain activity continuous & another activity discontinuous but there is no variation in conditions.

Example: Assume we are talking about treatment of wastewater from industries A, B, C, D…etc. There will be sequential batch feeding to SBR. However, wastewater treatment for a single industry (say B) will be done in S-CR with intermittent feeding to the reactor but the reactor & the effluent will continuously have the water coming from B.

According to my opinion Sequencing Batch Reactor is a fill-and draw activated sludge system for wastewater treatment.Please see for example

https://www3.epa.gov/npdes/pubs/sbr_new.pdf http://www.neiwpcc.org/neiwpcc_docs/sbr_manual.pdf

Semicontinuous feeding could be used for cultivation or fermentation, for chemical reaction, cell culture, casting, cvrystallization etc.it means generally for various purposes 

http://www.uni-saarland.de/fak8/heinzle/de/teaching/Bioreaction_engineering/Seminare/Henry_CHO_Fedbatch_BTProg_2008.pdf

Best regards

Vit

In the semi-continuous system, the volume of the reaction mixture changes (grows). The ntensity of the process  the intensity of the thermal effects may be easier  controlled . Unfortunately, there is a greater risk of infection.

That the start.

Regards