Investigating reverse osmosis membrane fouling and scaling by membrane autopsy of a bench scale device

Abstract

In response to the escalating world water demand and aiming to promote equal opportunities, reverse osmosis desalination has been widely implemented. Desalination is however constantly subjected to fouling and scaling which increase the cost of desalination by increasing the differential pressure of the membrane and reducing the permeate flux. A bench-scale desalination equipment has been used in this research to investigate the mitigation of fouling and scaling. This study involved the performance of membrane autopsy for fouling characterisation with special attention to flux decline due to sulphate precipitation and biofouling. Visual inspection, scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and microbiology tests (API) were performed. Results obtained showed the presence of diatoms, pseudomonas and polysaccharides as the main foulants causing biofouling. Analysis revealed sulphate deposits as well as aluminium, calcium and silica as the main elements contributing to inorganic scaling. Findings pointed out that the pre-treatment system of the small-scale reverse osmosis water treatment was inefficient and that selection of pre-treatment chemicals should be based on its compatibility with the membrane structure. The importance of characterisation for the verification of fouling mechanisms is emphasised.

Applications and Challenges of the Reverse Osmosis Membrane Process: A Review

“…Organic materials include humic, proteins, lipids, organic acids, and natural organic matter, which is produced by the breakdown of plants, microbes, and viruses [52,53]. Organic fouling was shown to be the most detrimental fouling and should be minimized as much as possible because the dissolved organic components in the feedwater serve as nutrition to the organisms whose development might contribute to significant biofouling [54]. Inorganic fouling, also known as scaling, is the deposition of soluble salts on membrane surfaces, which is one of the key challenges encountered throughout the desalination process [49].…”

A Review on Membrane Fouling Prediction Using Artificial Neural Networks (ANNs)

“…Membrane fouling is a major challenge in these processes, which can impair the performance of the membrane and increase operational costs [ 10 ]. Therefore, it is important to understand, diagnose, predict, and mitigate fouling occurrences for the sustainable and efficient operation of membrane-based processes [ 11 ].…”

Sulfonated Reverse Osmosis Membrane with Simultaneous Mitigation of Silica Scaling and Organic Fouling

“…Water resource shortages have become a global problem. Approximately 50% of people worldwide suffer from severe water shortages, and this situation is becoming increasingly serious. − Reverse osmosis (RO) membranes are extensively utilized in desalination processes contributed to the advantages of low equipment investment, simple operation, and low energy consumption with only 2.5 kW·h·m –3 purified water. , Currently, more than 90 million m 3 of desalted water is produced every day from 18500 desalination plants around the world, in which RO technology accounts for 65% of the total production capacity. − However, regardless of the great advantages of RO membranes, inorganic scaling and organic fouling are still limiting factors for further application of RO membranes. − …”