Membrane bioreactor with nonwoven fabrics as solid–liquid separation media for wastewater treatment

A nonwoven fabric module was utilized as a solid–liquid separation medium in a membrane bioreactor (MBR) for treating wastewater. The experimental results indicated that nonwoven fabrics had lower filtration resistance than microporous membranes in MBR applications. The optimal aeration intensity was approximately 0.01 m3/m2 s. The effect of mixed liquor suspended solid concentration on filtration resistance was not significant at an operating flux of under 0.8m3/m2 d in the study range. The performance of nonwoven fabrics in a MBR application was further demonstrated in a pilot test. Chemical oxygen demand (COD) and suspended solids (SS) in the effluent were maintained under 60 and 10 mg/L, respectively, whereas influent COD varied from 800 to 1800 mg/L. The transmembrane pressure was maintained below 5 kPa at a permeation flux of 0.18 m3/m2 d. The experimental results demonstrated that nonwoven fabrics maintained stable operation in MBR applications under appropriate operating conditions.

Application of nonwoven fabric materials in MBRs is still under development. This work demonstrated that properly designed nonwoven fabric materials can be employed as solid–liquid separation media in a MBR for treating wastewater. Basically, nonwoven fabrics had a lower filtration resistance than a microporous membrane in MBR application. The optimal aeration intensity was approximately 0.01 m3/m2 s in this work. The effect of MLSS concentration on filtration resistance was not significant at operating fluxes of under 0.8 m3/m2 d in the range of interest. An appropriate operating strategy, such as optimizing the operating flux or implementing the fouling control method, is required for long-term stable operation, in the application of nonwoven fabrics in MBR.