Full Description

The traditional method for determining whether a membrane is considered an ultrafiltration (UF)or microfiltration (MF) membrane is based upon the molecular weight cutoff of the membrane.Microbial removal performance does not currently play a quantitative role in determiningwhether a membrane is classified as MF or UF. This leads to ambiguity in the classification oflow-pressure membranes. The overall goal of this AwwaRF-funded research is to develop asystematic performance testing protocol and specification for MF and UF membranes withrespect to removal of viral and submicron bacterial pathogens with various water qualities andoperating conditions. Pilot studies were conducted at the Atlanta Fulton County WaterTreatment Plant in Georgia, with a continuous microfiltration (CMF) unit (hollow fiber, PVDFmembrane) to evaluate its capability to remove microorganisms under selected water qualityand operational conditions. The microorganisms tested were MS2 phage, PRD1 phage andPseudomonas diminuta. The pilot was fed with dechlorinated tap water (finished water) or rawwater from the Chattahoochee River. Pseudomonas diminuta was removed to the detection limitof its assay (5-6 Logs) while using dechlorinated tap water. When fed with raw water and afterallowing cake to form on the membrane, the system achieved an average removal of 0.7 Log(MS2) and 2.3 Log (PRD1). In comparison, low removal of MS2 and 1.4 Log-removal of PRD1were observed while using dechlorinated tap water. Under these conditions, the flowrateappeared to have very little effect, if any, on the removal of MS2 and PRD1 phages. The resultsobtained at bench-scale were comparable to the pilot-scale results. The highest viral removalwas observed under the hydraulically/pneumatically irreversible fouling conditions (PRD1=4.1-6.1 Log; MS2=0.5-5 Log). This can be attributed to a greater specific flux decline during theextended operation of irreversible fouling conditions. Includes 9 references, tables, figures.

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Edition: Vol. - No. Published: 03/05/2003 Number of Pages: 17File Size: 1 file , 590 KB