Antifouling grafting of ceramic membranes validated in a variety of challenging wastewaters

Abstract

Compared to traditional separation and purification techniques, membrane filtration is particularly beneficial for the treatment of wastewater streams such as pulp and paper mill effluents (PPME), olive oil wastewater (OOWW) and oil/gas produced water (PW). However, severe membrane fouling can be a major issue. In this work, the use of ceramic membranes and the potential for the broad applicability of a recently developed antifouling grafting was evaluated to tackle this issue. To this end, the fouling behavior of native and grafted membranes was tested in the selected difficult wastewater streams, both in dead-end and in cross-flow mode. In addition, the quality of the produced permeate water was determined to assess the overall performance of the investigated membranes for reuse or recycling of the treated wastewater. The obtained results show that grafting significantly enhances the antifouling tendency of the ceramic membranes. Particularly, the membrane grafted with methyl groups using the Grignard technique (MGR), showed in all cases no or negligible fouling as compared to the native membrane. As a consequence, the process flux or filtration capacity of the MGR membrane in cross-flow is always higher and more stable than the native membrane, even though the grafting lowers the pure water flux. Hence, the inert character of the MGR membrane is repeatedly proven and shown to be broadly applicable and generic for anti-fouling, without loss in permeate quality. Moreover, in case of OOWW, the quality of the MGR permeate is even better than that of the native membrane due to its lower fouling. All results can be explained taking into account the physico-chemical properties of foulants and membranes, as shown in previous work. In conclusion, the use of MGR membranes could provide an optimum economical solution for the treatment of the selected challenging wastewaters.

Antifouling membranes for oily wastewater treatment: Interplay between wetting and membrane fouling

“…In addition to oil foulant, real-world oily wastewater contains various other kinds of foulants, such as organic foulants, inorganic foulants and biofilms. [18,21,50,143] It is challenging to prevent fouling by these foulants at the same time. Property of the membrane (e.g., surface hydrophilicity and structure) and the wastewater (e.g., composition and concentration), configuration of the filtration module, and operation conditions are all relevant to membrane fouling during filtration.…”

“…[16,30,74,84,85] Their influence on membrane fouling during wastewater treatment is multiple. [11,13,18,22,86,87] First, surfactants can be adsorbed on/in the membrane and increase its resistance to water permeation (especially for UF and NF membranes since they have small pores), and the surfactant micelles may also block the pores leading to flux decline. [11] In this respect, surfactants act as foulants during membrane filtration.…”

Wetting Resistance of Commercial Membrane Distillation Membranes in Waste Streams Containing Surfactants and Oil

“…The components were mixed and ultrasound was applied for 30 min to stabilize the suspension. For the oil-in-water emulsion, the size of the oil droplets was measured by a particle size analyzer (Nanosight NS500, Malvern Instruments Ltd., Malvern, UK) and was found in the range of 0.1-0.5 µm with an average particle diameter of 0.3 µm [29].…”

“…Finally, a standard oil-in-water emulsion was prepared and tested with MD. The composition simulates the composition of produced water, which is a common waste stream in the oil and gas production [29].…”

The critical pressure for microfiltration of oil-in-water emulsions using slotted-pore membranes

“…The efficient microfiltration of oil-in-water emulsions, that are commonly found in produced water from oil/gas recovery or as a byproduct of metal finishing processes, is important for protection of the aquatic environment and recovery of clean water [1,2]. The advantages of the membrane filtration methods, as compared to sedimentation, dissolved gas flotation and centrifugation, include relatively low maintenance cost, mechanical stability and simple operating conditions [3][4][5][6]. The membrane separation process is based on rejection of nonwetting oil droplets that are larger than membrane pores, while at the same time allowing permeate flux, which is induced by the applied pressure across the membrane.…”