Enhancement of Oily Wastewater Treatment by Ceramic Microfiltration Membranes using Powder Activated Carbon

Abstract

Results of a hybrid microfiltration-powdered activated carbon (MF-PAC) system for the treatment of synthetic oily wastewaters with mullite and mullite-alumina (50 % alumina content) ceramic membranes are presented. The experiments were conducted to determine the effects of the presence of PAC on MF process performance in terms of flux decline, membrane fouling, and total organic carbon (TOC) rejection. The experimental results demonstrate that PAC addition at low concentration (200-400 ppm) increases permeate flux by 19.6 % for mullite and 61 % for mullite-alumina MF membranes. However, high PAC concentration (1200 ppm) decreases the permeate flux by 22 % for mullite and 25 % for mullitealumina MF membranes. Also, TOC rejection increases from 93.8 to 97.4 % for mullite and from 89.6 to 92.4 % for mullite-alumina MF membranes. IntroductionLow pressure driven membrane separation techniques such as microfiltration (MF) have been considered as indispensable treatment methods in water and wastewater treatment applications to remove specific pollutants which are not normally removed by conventional processes. MF is excellent in removing microparticles, microorganisms, macromolecules, and most bacteria [1]. Ceramic membranes have numerous advantages: stability at high temperature and pressure resistance, good chemical stability, high mechanical resistance, long life, and good antifouling properties. Ceramic MF membranes can be made from alumina, mullite, cordierite, silica, spinel, zirconia, and other refractory oxides. Among these membranes, mullite ceramic membranes have very high chemical and thermal stability, and are very cheap because they can be prepared by extruding and calcining kaolin clay [2].Membrane fouling is characterized, in general, as the reduction of permeate flux through the membrane and, hence, leads to an irreversible loss of system productivity over time, caused by interactions between the membrane and the various components in the process stream. To reduce membrane fouling, some methods can be used. Using adsorbents as pretreatment is one way to minimize membrane fouling. Powdered activated carbon (PAC) 1) has the ability to adsorb primarily the lower molecular weight organic compounds and shows more affinity towards the hydrophobic components. Adsorption using PAC in combination with the membrane MF process can be used as a hybrid system for removing organic materials and improving permeate flux. PAC is generally used as a pretreatment step prior to the membrane operation or in combination with the membrane in a feed tank [3].PAC has been used as membrane pretreatment for both water and wastewater treatment. Kim et al. [4] showed that using PAC with polymeric MF membranes to treat lake water reduces the fouling rate by removing natural organic matter (NOM), compared with the system with no adsorbent. Ince et al. [5] used PAC and polymer membranes in a hybrid system to further reduce the chemical oxygen demand (COD) concentration of the jet-loop membrane bioreactor effluent to meet the COD disc...

Elaboration and characterization of novel two-layer tubular ceramic membranes by coating natural zeolite and activated carbon on mullite-alumina-zeolite support: application for oily wastewater treatment

“…As revealed by the figure, the PF of the support and MF membranes fell rapidly at the beginning of the operation, while it declined modestly thereafter. To explain, this reduction was caused by the adsorption and deposition of oil droplets on the inner surface of the membrane, which formed a cake or a gel layer [37,38], leading to higher hydrodynamic resistance [8].…”

Experimental Study and Modeling of Ultrafiltration of Refinery Effluents Using a Hybrid Intelligent Approach

“…15 It can be elucidated that increasing temperature increases the osmotic pressure slightly (it is proved by considering the Van't Hoff equation together with Darcy's law) and subsequently decreases permeation flux 18 but decreases the feed viscosity and, thus, increases the solvent and solute permeabilities (diffusivities), resulting in increasing flux. 3,18,40,83,84 As demonstrated in Figure 4a, it is clear that the permeate flux increased sharply with increasing temperature up to 37.5 °C, and then with further increasing temperature, permeation flux increased slightly. Indeed, the viscosity effect on the permeate flux is predominant at lowered temperatures; on the other hand, the osmotic pressure effect enhances at elevated temperatures.…”

“…Treatment of this kind of wastewater requires reliable purification systems to meet environmental discharge standards (oil content < 5 ppm) . Membrane-based separation processes, particularly microfiltration (MF) and UF processes, are proving to be promising alternatives for conventional industrial separation methods, due to their numerous advantages such as high selectivity, easy separation, mild operation, continuous and automatic operation, no need for extraneous chemicals, high-purity products, much lower environmental impact, and economical and fast operation, as well as relatively low capital and running investment. − According to previous studies, − high volumes of domestic, industrial, oil-in-water, and oily wastewaters were treated with MF and UF processes to exceptionally high-quality standards, usually for reuse purposes.…”

Low-cost ceramic membranes: Synthesis, classifications, and applications

“…In another work, Abbasi et al [102] have studied the effect of adding powdered activated carbon to mullite, on the one hand, and mulliteealumina mixture (50/50 wt%) on the other hand on TOC reduction. Their experimental results prove that the addition of high concentration (1200 ppm) powdered activated carbon enhances the elimination of TOC from 93.8% to 97.4 % and from 89.6% to 92.4 % for mullite and mulliteealumina MF membranes, respectively.…”