AWWA WQTC60680

Nanofiltration of surface waters has been successfully implemented at large scale facilities toimprove water quality. In this work we examine the effect of several advanced pretreatmentoperations following conventional treatment by coagulation through filtration on membraneperformance.Effluent samples of processes at a full-scale plant were obtained for subsequent treatment bymembrane filtration in both dead-end batch filtration experiments and in cross-flow filtration.Dead-end experiments were designed to extract information on spontaneous flux as a functionof recovery (up to 85%) while cross flow experiments were operated at a constant recovery of75%. At the conclusion of each experiment, membranes were imaged by scanning electron microscope (SEM) and, in somecases, energy dispersive spectrometry (EDS) to obtain information on foulant structure and composition.Among the advanced pretreatment processes evaluated, granular activated carbon (GAC) pretreatment, combined withozone, reduced fouling of both of the membranes tested to the greatest extent. Ultraviolet (UV) irradiationand pre-filtration through a 5um membrane did not measurably reduce fouling. Neither of thesepretreatment processes appreciably reduced the total organic carbon (TOC) of the membrane feed. GAC pretreatmentwas further investigated in terms of the age of GAC used to perform the pretreatment. GAC agewas not found to significantly affect fouling. This latter observation suggests that the primarybenefit of GAC pretreatment may be related to biological activity on the GAC filters. Includes 5 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/15/2004

Number of Pages:

9

File Size:

1 file , 1.2 MB