A Rotating Hollow Fiber Module for Fouling Control in Direct Membrane Filtration of Primary Settled Wastewater

Abstract

Direct membrane filtration (DMF) has emerged as an attractive option to treat municipal wastewater; however, this technology suffers from severe membrane fouling. In this paper, a rotating hollow fiber module for enhancing the fouling control is proposed. The experimental study was conducted at lab scale, filtering a primary settled municipal wastewater. The effectiveness of this technology coupled with physicochemical pretreatment was also evaluated. Results showed the existence of a threshold permeate flux (32–36 L/h·m2), below which the shear rates exerted by membrane rotation prevented supramicron size particle deposition, regardless of the application of physicochemical pretreatment, even at low rotational speeds (w = 120 rpm). At higher fluxes (40–48 L/h·m2), the rotational speed had to be increased to 340 rpm to achieve sustainable conditions. Even when applying physicochemical pretreatment, the internal residual fouling was found to be the main fouling contribution, probably associated with the submicron particles.

Direct Membrane Filtration for Wastewater Treatment Using an Intermittent Rotating Hollow Fiber Module

“…Results also suggest that there was a low-turbulence region (N ≤ 45 rev•min −1 ; Re ≤ 5152) where the shear rates are too weak to control pore blocking. In agreement with a recent work, the reason of this trend may be related to the deposition of micron and submicron-size particles on the membrane surface, which could not be mitigated operating at low shear rates [27]. On the other hand, Figure 6b shows K c •TMP 0 profiles against N, where the values remained approximately constant at ~630 kPa•m −1 until the rotation speed reached the turning point.…”

“…The control system also allows setting the main operating variables: the permeate and backwashing fluxes (J and J B , respectively), the filtration and backwashing cycle time (t F and t B , respectively) and the intermittence operation of the stirrer. A detailed description of the experimental unit can be found in Ruigómez et al [27].…”

“…In fact, previous studies have applied vibrating membranes in DMF, showing a better fouling control than air sparging [25,26]. Based on this approach, a novel rotating hollow-fiber module was applied for filtering raw wastewater, showing a performance comparable to that obtained for a pre-coagulated wastewater [27]. Nevertheless, the application of a fixed rotation speed in the module becomes energy intensive, while intermittent rotation seems to be energy-effective to prevent membrane fouling.…”

Direct Membrane Filtration of Wastewater: A Comparison between Real and Synthetic Wastewater

“…Despite the appeal of the process, the main drawback of DMF remains membrane fouling [8][9][10]. Fouling causes an increase in resistance to filtration over time, which can lead to both lower operating fluxes and higher transmembrane pressures (TMPs).…”

Effect of UF Membrane Rotation on Filtration Performance Using High Concentration Latex Emulsion Solution

“…With this in mind, many studies on rotating membrane systems have been conducted in the past, particularly in regions where the solution concentration is low [1] and with cylinder-type membranes that make it difficult to produce a device with a large membrane area that can be used industrially [2,3]. In recent years, different effects of rotation have been reported, such as the effect of preventing fouling by rotating the hollow fiber membrane for sewage treatment [4]. In addition, the design parameters governing the permeation characteristics of rotating cylindrical membranes have been identified [5].…”