MBR-based treatment
schemes performed much better (mean of 80% COD removal across
all installations at HRTs of 2–3 days) than conventional systems
(around 63% COD removal at much longer HRTs of 25–45 days)
when the performance of the two systems were compared for treatment of old LFL of BOD/COD ratios 0.3 or less. It is therefore clear
that the application of conventional biological processes is limited
to LFL with BOD/COD ratios of 0.2 or higher whereas MBRs can be
satisfactorily used for LFL with BOD/COD ratios less than 0.2.