Abstract:
Preflocculation reduces the fouling of membranes in cross-flow rnicrofiltration
(CFM) thus leading to high quality product water at economic filtration
flux. As such, this hybrid system will have a major impact in treating the
biologically treated sewage effluent. The preflocculation achieved through
the floating medium flocculation (FMF) was found to increase the phosphorus
removal up to 96%. The decline in microfiltration permeate flux
with time was reduced by the incorporation of flocculation. However, the
improvement in the removal of dissolved organic carbon (DOC) was marginal (from 20% with membrane alone to 46% with the membrane-flocculation
hybrid system). The flocculation followed by adsorption as pretreatment
helped to increase the DOC removal as high as 98%.
Flocculation was found to remove more than 66% of colloidal effluent
organic matter (EfOM). An attempt was also made to quantify the hydrophobic
fraction in the pretreated effluent and to identify the molecular
weight (MW) range of organics removed by the flocculation. The pretreatment
of flocculation was found to remove 68.5%, 61.8%, and 62.9% of
hydrophobic, hydrophilic, and transphilic organic matter. The MW size distribution
analysis indicated that flocculation with ferric chloride removed a
majority of organic matter in the MW range of 300-5000 Da.
