Flux Improvement and Biofilm Performance of an Oblique Gravity-Driven Ceramic Membrane Bioreactor Coupled with Electrocoagulation for Roofing Rainwater Purification

In stormwater harvesting, an effectivemethod to avoidfloodingrisk and pollutant migration, the collected roofing rainwater canmeet part of the domestic water demand and alleviate the water resourcescrisis. In the current work, an innovative oblique membrane tank layoutmode was involved in the electrocoagulation coupled with a gravity-drivenceramic membrane bioreactor (EC/GDCMBR), which was suitable for distributedroof rainwater treatment facilities in rural water-scarce areas. Theoblique-EC/GDCMBR system could improve the biofilm formation and porosityin the membrane tank to realize rainwater treatment and reuse. Comparedwith the traditional layout of lateral-EC/GDCMBR during the long-termoperation of 82 days, the oblique-EC/GDCMBR system not only presentedthe improved permeation flux of & SIM;40 LMH compared to that oflateral-EC/GDCMBR (& SIM;34 LMH), but also exhibited a lower irreversiblefouling resistance (oblique: 1.68 x 10(9) m(-1) vs. lateral: 2.02 x 10(9) m(-1)).Moreover, the biofilm characteristics were determined to evaluatethe improved flux and biofilm in oblique-EC/GDCMBR. Confocal laserscanning microscopy (CLSM) and adenosine triphosphate (ATP) contentsalso confirmed the higher biological activity in oblique-EC/GDCMBR.The abundance of Denitratisoma (& SIM;15.38%) inthe sludge and Nitrospira (& SIM;3.35%) in thebiofilm explained the different nitrogen removal approaches in oblique-EC/GDCMBR.Besides, oblique-EC/GDCMBR exhibited excellent water purificationperformance with the standard effluent water quality. In a word, thiswork presents the advantage and reliability of oblique-EC/GDCMBR forroofing rainwater sustainable treatment.

Automated summary

This study introduced an innovative oblique membrane tank layout combined with the electrocoagulation and gravity-driven ceramic membrane bioreactor technology, which was suitable for rural water-scarce areas. Compared with the traditional lateral-EC/GDCMBR layout, the oblique-EC/GDCMBR system exhibited improved permeation flux and lower irreversible fouling resistance. The research confirmed the advantage and reliability of the oblique-EC/GDCMBR system for sustainable treatment of roofing rainwater.