Application of ultrafiltration ceramic membrane for separation of oily wastewater generated by maritime transportation

Abstract

This article addresses the applicability of the ultrafiltration ceramic membrane for separation of oily wastewaters generated during maritime transportation. The UF experiments were performed in a cross-flow system using a pilot-scale installation. The membrane used had a separation cut-off equal to 8 kDa and an active area of 0.0038 m2. The experiments were conducted in a wide range of temperature (303 and 323 K), tangential flow rate (2.9–8.2 m/s) and transmembrane pressure (0.28–0.40 MPa). The excellent separation properties of the ceramic UF membrane have been confirmed. It allowed to obtain a high-quality, oil-free permeate with the turbidity at the level of about 0.2 NTU. However, wastewaters caused the intensive membrane fouling, which significantly decreased the process performance. Most often, the permeate flux was stabilized after about 100 min of the process running and the steady-state flux at 30% of its maximum value was obtained. The effects of wastewater pre-filtration and feed pH on the UF process performance have been studied. It was found that the pre-filtration of oily wastewaters adversely affects the permeate flux. For analyzing the fouling mechanisms, Hermia’s model was used. Importantly, different ways of membrane rinsing were applied. Regardless of the degree of membrane contamination, the effective membrane cleaning was achieved using 1–3 wt% NaOH and H3PO4 solutions.