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Effect of phosphorus addition on biofiltration pre-treatment to reduce ultrafiltration membrane fouling

2016; Taylor & Francis; Volume: 57; Issue: 52 Linguagem: Inglês

10.1080/19443994.2016.1145602

1944-3994

Irfan Ur Rahman, Michele I. Van Dyke, William B. Anderson, Xiaohui Jin, S. Ndiongue, Peter M. Huck,

Wastewater Treatment and Nitrogen Removal

AbstractA pilot-scale study investigated the effect of phosphorus addition on a drinking water biofilter used to reduce fouling of an ultrafiltration membrane. Biofiltration without pre-treatment (BFwp) has been shown to be an effective pre-treatment for the removal of natural organic matter (NOM) components that cause membrane fouling. However, the river source used in this study was found to have low phosphorus concentrations that could potentially affect biofilter biomass levels and NOM biodegradation. The river water source (Saugeen River located at Walkerton, Ontario, Canada) had a high total organic carbon (4.34–6.61 mg/L) of primarily humic content, variable turbidity, and seasonal changes in water temperature (9.7–19.9°C) as measured over the study period. Phosphorus was added to the biofilter influent at 0.01 mg P/L, and later at 0.05 mg P/L, over a four-month period. Biofilter activity, NOM removal, and membrane performance were compared to a control system operating under identical conditions but without nutrient addition. Filter biomass measured by ATP and fluorescein diacetate hydrolysis (overall enzyme activity) was stable over time, with no difference between control and phosphorus-amended biofilters. As well, phosphorus addition did not improve the removal of NOM fractions, especially biopolymers that are important for membrane fouling. There was a small initial increase in the removal of dissolved organic carbon and humic substances after phosphorus addition, but this effect diminished over time. The effluent from each biofilter was used to operate an ultrafiltration membrane system using conditions similar to full scale. Membrane fouling for each experiment was measured over 1.5 d, and operating cycles included 30-min permeation followed by backwashing/air sparging. Results showed that there was no difference in hydraulically reversible or irreversible fouling of membranes fed with the effluent from control or phosphorus-amended biofilters. It was found that biofilter nutrient feed requirements are likely site specific, and affected by factors including biomass and NOM characteristics.Keywords: BiofiltrationFoulingNatural organic matterPhosphorusUltrafiltration AcknowledgementsThis project was funded by an Ontario Research Fund Research Excellence grant, and by the Natural Sciences and Engineering Research Council of Canada in the form of an Industrial Research Chair in Water Treatment at the University of Waterloo (UW) together with the Chair partners including Associated Engineering Group Ltd, the cities of Barrie, Brantford, Guelph, Hamilton and Ottawa, Conestoga-Rovers & Associates Limited, EPCOR Water Services, GE Water & Process Technologies Canada, Lake Huron and Elgin Area Water Supply Systems, the Ontario Clean Water Agency (OCWA), the Regions of Durham, Halton, Niagara and Waterloo, RAL Engineering Ltd, Toronto Water, and the Walkerton Clean Water Centre. We thank the Walkerton Clean Water Centre for access to their facility and sampling related expenses, and GE Water & Process Technologies (Dr Daniella B. Mosqueda-Jimenez) for providing the UF membrane units. Additional thanks to Drs Monica Tudorancea and Sigrid Peldszus (UW) for LC-OCD analysis, and also Terry Ridgway (UW), and Laura Zettler (WCWC) for their valuable contributions to this study.