Adsorption capacity of biological powdered activated carbon in a hybrid membrane process for drinking water treatment

Hybrid membrane process integrates low-pressure driven membrane filtration to activatedcarbon (AC) adsorption. One of their main features is the possibility of operating either in adsorptionor in biological mode, which can be accomplished by shifting the AC residence time (i.e., sludge age)within the reactor. The purpose of this work was to evaluate the adsorption capacity of PACmaintained in a hybrid process operated in biological mode (at 10 and 60 days of sludge age) and tocompare it with that of the same virgin (i.e. uncolonized) material. For that purpose, kinetic tests werecarried out using methylene blue as the adsorbate (10-5 M). A pseudo second order model was fitted tothe kinetic data with good compliance. The results showed an inverse relationship between qe and theinitial PAC dose. Although both biological PAC lead to lower adsorption rates than the uncolonizedmaterial, our results indicate that the adsorption mechanism plays a role in hybrid processes eventhough they are operated at high sludge ages.