Related Experiment Video
Updated: May 26, 2026

Continuously-stirred Anaerobic Digester to Convert Organic Wastes into Biogas: System Setup and Basic Operation
Published on: July 13, 2012
Anaerobic co-digestion of waste activated sludge and greasy sludge from flotation process: batch versus CSTR
R Girault1, G Bridoux, F Nauleau
1Cemagref, UR GERE, 17 av. de Cucillé, CS 64427, F-35044 Rennes, France. romain.girault@cemagref.fr
Abstract:
In this study, the maximum ratio of greasy sludge to incorporate with waste activated sludge was investigated in batch and CSTR experiments. In batch experiments, inhibition occurred with a greasy sludge ratio of more than 20-30% of the feed COD. In CSTR experiments, the optimal greasy sludge ratio was 60% of the feed COD and inhibition occurred above a ratio of 80%. Hence, batch experiments can predict the CSTR yield when the degradation phenomenon are additive but cannot be used to determine the maximum ratio to be used in a CSTR configuration. Additionally, when the ratio of greasy sludge increased from 0% to 60% of the feed COD, CSTR methane production increased by more than 60%. When the greasy sludge ratio increased from 60% to 90% of the feed COD, the reactor yield decreased by 75%.
Related Concept Videos
Bioreactor Design and Operational System
Bioreactor Controls-II
Scale-Up Processes
Batch vs Continuous Culture

