Combining submerged membrane technology with anaerobic and ...

OLR (kgCOD·m -3·d -1 )Tertiary membrane filtration of industrial wastewater using granular or flocculent biomass SBRskgCOD·m -3·d -1 (Beun et al., 1999)). The wastewater fed to the F-SBR had a lower CODconcentration (between 100 and 400 mg·L -1 ) than that fed to the G-SBR (between 400 and800 mg·L -1 ). The objective of periods III, IV and V was to compare the behaviour of the twoSBR at their recommended OLR and of the respective TMF chambers.6126 12 6←HRT (h)5Period IIIIIIIVV432100 50 100 150 200 250 300 350Time (d)Figure 3.3. Evolution of the applied OLR in the () F-SBR and (•) G-SBR systemsduring the four experimental periods.Figure 3.4 depicts the evolution of the overall COD removal percentage in bothsystems. During period I this overall COD removal percentage was referred to the solubleCOD in the effluent, since the absence of the TMF stage led to the wash-out of part of thebiomass from the system and hence to low total COD removal percentages. As can beobserved on figure 3.4, the COD removal efficiency was around 90 % for both systemsduring periods I and II. The presence of either flocculent or granular biomass in SBRsystems with tertiary filtration chambers did not affect COD removal efficiency, in terms ofsoluble COD. After period II, the COD removal efficiency in the F-SBR was lower than thatin the G-SBR because of the lower COD concentration in the feed water of the F-SBRduring periods III, IV and V. COD removal efficiencies in the flocculent system rangedbetween 66 and 97 %, whereas for the granular system, these efficiencies varied between89 and 96%.93