Mitigation and Removal of Biological Fouling in a Forward Osmosis Membrane Bioreactor
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Authors
Satterfield, Derrick James
Issue Date
2019
Type
Thesis
Language
Keywords
Air Scouring , Biological fouling , Forward osmosis membrane bioreactor , Membrane Cleaning , Osmotic Backwashing
Alternative Title
Abstract
The adherence of bacteria cells, extracellular proteins and polymers, and other organic materials on membrane surfaces can negatively impact the efficiency and economic feasibility of membrane-based treatment processes for wastewaters. Forward osmosis (FO) is an emerging membrane technology that utilizes an osmotic gradient rather than hydraulic pressure as a driving force to produce clean water. Because there is not a hydraulic pressure difference across the membrane, FO has a lower fouling propensity than other membrane processes, such as reverse osmosis or ultrafiltration, and thus is well-suited for use with wastewater sources containing high organic and biological loads. This work presents in situ cleaning methods for the mitigation and removal of biological fouling on FO membranes in a submerged osmotic membrane bioreactor. A novel FO membrane module was developed that allowed for three membrane coupons to be evaluated independently under the same biological conditions. Overall water production and energy efficiency were evaluated under different osmotic backwashing temperatures, durations, and frequencies, as well as with coupled mechanical scouring. Fouling propensity, fouling removal, and water flux was also examined with antibiotic dosed and heated draw solutions. Adding antibiotics to the draw solution is proposed to reduce and or mitigate biological fouling by producing a concentrated antibiotic layer on the membrane surface. Heating up the draw solution extends previous work showing increased fluxes by introducing fouling at these elevated temperatures to determine to what extent the increased operating flux trend remains.