Biofiltration Pre-treatment for UF Membranes: Experiences from a Pilot Scale Drinking Water Treatment Study

摘要

Broader application of ultrafiltration (UF) membranes in drinking water treatment is limited by particulate and organic fouling. This pilot-scale study has examined the ability of rapid biofiltration (without prior coagulation) to reduce fouling of a UF membrane treating an agriculturally and municipally impacted river. Earlier smaller scale and shorter duration studies demonstrated the viability of this "green" and robust pre-treatment approach and this study provides confirmation at pilot scale.Three different biofilter empty bed contact times (EBCTs) (5, 10 and 15 min) were investigated, using parallel dual-media filters. The hollow fibre membrane unit (ZW-10) was operated at constant flux. Only one membrane unit was available and experiments with a run time of at least 200 h were therefore conducted sequentially.Results indicate a beneficial effect of biofiltration pre-treatment on the rate of irreversible fouling, with increased EBCTs leading to lower rates of fouling. These results were reproducible, as demonstrated by the general similarity in the TMP slopes when repeating an experiment using the biofilter with the EBCT of 15 min. The biofilters also provided effective turbidity removal (i.e. mean effluent turbidities < 1 NTU).Overall, biofiltration pre-treatment for UF is a promising alternative. A particular niche application for this 'green' and robust treatment would be in small systems, where operational simplicity would be particularly important.