Troubleshooting Foaming in Membrane Bioreactor: Review of Foam Analysis, Causes and Remedies

Membrane Bioreactors have proved to be a useful alternative to conventional activated sludge systems for wastewater treatment. Merits of membrane bioreactors include more compact design saving a significant amount of space and lower sludge production due to longer sludge retention time. This system unfortunately has a downside with it comes to excessive foaming. Membrane bioreactors often act as foam traps leading to overflowing, wastage of sludge and difficulty in process control. Pre-Treatment of wastewater has proven to significantly reduce foaming caused by surfactants. Generally, physical methods are considered more economical and operationally convenient compared to conventional techniques including chemical treatment and advanced techniques like biological treatment. Polyaluminium chloride as a coagulant is recommended as a chemical treatment due to economic and effectiveness considerations. It has been concluded that the remedies for foaming issue are case specific and should be determined by the causes of foaming. This paper aims at reviewing techniques to analyse the foaming phenomenon, causes of foaming and its remedies to manage or eliminate foam