Effect Of Oxic Conditions On The Performance Of Membrane Bioreactor Systems – Pilot And Full Scale Evaluations

Membrane filterability tests were conducted at a full-scale pharmaceutical plant using external membranes and a pilot scale textile wastewater plant using submersed hollow fiber membranes. Side-by-side comparison of dissolved oxygen (DO) levels of 2.5-3.0 mg/L and 4-5.5 mg/L in separate trains at full scale show evidence of improved permeability and lower cleaning frequency for the high DO system. Pilot tests at DO levels of 2, 6 and 10 mg/L did not show a change in membrane permeability, although reductions in Extracellular Polymeric Substances (EPS) and Soluble Microbial Products (SMP) were observed at the highest DO level. The reduced cleaning frequency and difference in permeability trend for the full-scale plant suggests that oxic fouling mitigation strategies are a potential tool that can be deployed for the optimal maintenance of membrane systems, particularly when EPS and SMP are strong contributors to fouling rates.