Influence of Transparent Exopolymer Particles (TEP) Fouling on UF Ceramic Membranes and Associated Flux Recovery after Membrane Cleaning

摘要

Ceramic membranes are robust against high pressure and extreme pH (1-14). Theycan sustain aggressive backwashing fluxes that provide more effective hydrauliccleaning compared to polymeric membranes. Recovery of permeability aftermembrane cleaning (either hydraulically or chemically) is important to maintainsustainable operation. This research aimed to assess the effect of transparentexopolymer particles (TEP) on the fouling of UF ceramic membranes in seawaterapplications. An Anopore ceramic UF membrane (AAO20) with a pore size of 20 nmand a TAMI-UF ceramic membrane with a 12 nm average pore sizes were used with aconstant pressure set-up. Red Seawater collected from Thuwal Saudi Arabia was usedas feed water. Milli Q water was used for hydraulic backwashing (BW) instead ofpermeate to prevent cross contamination. Sodium hypochlorite was used for chemicalenhanced backwashing (CEB) and chemical cleaning (CIP) of AAO20 membranes.Ozonated Milli Q (with 10 mg/l ozone) was used for CEB of TAMI-UF membranesand AAO20 membranes. Filtration cycles of 30-60 minutes were adopted. A highbackwashing flux between 500 - 1500 LMH was applied for BW and CEB for 2minutes. The membrane surfaces (fouled and cleaned) were analysed with SEM, EDXand Epifluorescence Microscopy. The results showed that AAO20 membranesbackwashed with Milli Q attained 10-15% flux recovery. The use of CEB (sodiumhypochlorite 3000 ppm) improved flux recovery to 80% and almost 100% after CIP.TAMI-UF membranes achieved average recovery of 35 % after backwashing andimproved to over 80% with CEB. The low recovery after backwashing was attributedto the presence of TEP retained on the membranes that are hypothesized to be moresticky and difficult to be removed by hydraulic backwashing. TEP showed resistanceagainst hydraulic backwashing resulting into low flux recovery. The use of ozonatedMilli Q and sodium hypochlorite for CEB played an important role in breaking up thestructure of TEP (which exhibited behaviour of attaching other foulants) and henceimproved the flux recovery.