Mixed Liquor Property Change with Densified MBR: Impact on Biology and Membrane Performance?

Mixed liquor property change with MBR + DAS: impact on biology and membrane performance? Overview Research background: Detroit Lakes Trial Preliminary results What is memDENSE, Full-scale MBR Densification & densification? membrane performance 1 2 3 MBR performance improved with hydrocyclone, due to removal in Overflow of lighter flocs and colloidal fraction from the mixed liquor WE TARGET: lower fouling rate below 0.7Wenxiang Zhang et al, 2018 demonstrated the 1.0 mm diameter = DENSIFICATION existence of a critical AGS size (1~1.2 mm) above which membrane fouling is increased and pore higher fouling rate > 1-1.2 mm, blocking higher than cake layer more fines = more pore blocking Supporting research- densification & granulation with MBR bridging densification size & fraction, research background on granule size & pore blocking with densification & AGS with MBR membrane filtration Donnaz et al, 2020 showed that biomass densification more stable & lower fine improves sludge settling of clarifiers w/ bio aggregates colloids with HC size distribution 200 – 500 um (1000 max) Nogushi et al, 2018 showed that less membrane cleaning MBR mixed liquor quality can be enhanced by CIP with HC hydrocyclone. a promising coupling mem DENSE MBR + densification = performance of membranes with MBR are limited by the characteristics of the mixed liquor memDENSE allows controlling and stabilizing sludge characteristics (biological matrix) fundamentals biology wash out low value inventories bio-accumulate high value inventories membrane lower cake layer resistance, lower super fine colloidal organics < 1.5 microns in Membrane Tank Detroit Lakes Trial Full-scale MBR MT Oxic Anoxic Anaerobic memDENSETM demonstration Detroit Lakes WWTP – Minnesota, US 1. MGD ADF, MGD PHF waterline: ○ equalization tank, ○ pretreatment (grit removal) ○ ZeeWeed-MBR (A2O), UV disinfection sludge line: MT Oxic ○ membrane thickener (ZeeWeed), Anoxic Anaerobic ○ aerobic digestion, memDENSETM demonstration ○ dewatering by centrifuge Detroit Lakes WWTP – Minnesota, US Problem to solve: Significant foaming Seasonal permeability struggles Spring melt high flows Industrial discharge Strengthen phosphorus removal MT Oxic bioP plant with 0.067mg/L discharge limit Anoxic Anaerobic memDENSETM demonstration Densified MBR – effect on permeability – Maintained high permeability with temperature drop – Less recovery cleans – 10-15 gfd/psi increase over pre densification TTF dropped, Permeability increased Oxygen transfer improved Mixed liquor microbial matrix shifted, DI increased What’s next: Confirming correlations with permeability over time Study of resistance and pore blocking as densification continues Long-term benefits to MBR performance.