:: Volume 7, Issue 2 ( Spring 2020) ::
Environ. Health Eng. Manag. 2020, 7(2): 119-126 Back to browse issues page
Seawater reverse osmosis membrane fouling causes in a full scale desalination plant; through the analysis of environmental issues: raw water quality
Leila Rezaei , Mohsen Dehghani , Amir Hesam Hassani , Vali Alipour
Corresponding author:Department of Environmental Health Engineering, School of Health, Hormozgan University of Medical Sciences, Iran , v_alip@yahoo.com
Abstract:   (3463 Views)
Background: Membrane clogging is one of the most important problem for desalination plant operators in Iran, therefore, this study was conducted to investigate the main causes of this problem using field analysis.
Methods: In this study, six continuous membranes in a reverse osmosis (RO) pressure vessel under the 33-month service period (April 2017 to November 2019) were selected. The membranes were analyzed through visual evaluation of the outer and inner membrane surface, analyzing the damages and physical harms, oxidative stress tests, iron spot test, fouling chemical analysis using loss on ignition (LOI) tests, X-ray fluorescence (XRF), and Fourier transform infrared (FTIR) spectroscopy.
Results: Particle size distribution in raw seawater (EC = 55 000 µs/cm, turbidity = 11 NTU) was 66.4% smaller than 1 µ and 28.3% between 1 to 1.9 µm. Physical damages were not seen on the membranes but telescopic damages were observed which was due to membrane fouling. Removal efficiencies of turbidity and silt density index (SDI) were 84% and 18%, respectively. Membrane oxidation was also seen. Most of the sediments compositions on the membranes were SiO2, Al2O3, MgO, and Fe2O3. Biological fouling was detected on the membranes surface.
Conclusion: Inaccurate use of chlorine neutralizer caused the residual chlorine to be present in the membrane entering water, which damaged the membrane. Accumulation of clogging agents on membrane surface showed malfunction of pretreatment function, therefore, revision of design and operation of units is necessary. Biological fouling is due to non-effective pre-chlorination of drinking water. Metallic compounds sedimentation on the membrane is due to improper use of anti-fouling chemicals. High SDI in the influent shows the need to change the cartridge filters.
 
Keywords: Seawater, Drinking, Chlorides, Particle size, Spectroscopy, Fourier transform infrared, Iran
eprint link: http://eprints.kmu.ac.ir/id/eprint/32726
Full-Text [PDF 1045 kb]   (1420 Downloads)    
Type of Study: Original Article | Subject: Special
Received: 2020/07/25 | Accepted: 2020/05/30 | Published: 2020/08/5

Ethics code: HUMS.REC.1396.174



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Volume 7, Issue 2 ( Spring 2020) Back to browse issues page