Algal blooms: an emerging threat to seawater reverse osmosis desalination

Villacorte, Loreen O.; Tabatabai, S. Assiyeh Alizadeh; Dhakal, Nirajan; Amy, Gary L.; Schippers, Jan C.; Kennedy, Maria D.

doi:10.1080/19443994.2014.940649

Cited by 67 publications

(33 citation statements)

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“…These peaks might have originated entirely from the medium, i.e., EDTA added to the algal culture, which was used as a chelating agent to minimize the precipitation of metals in the medium. The LC-OCD analysis of EDTA showed a peak at a retention time (50 -57 minutes) (Villacorte et al, 2015b) …”

Section: Comparison Of Fouling Potential Of Aom and Aom + Algal Cellsmentioning

confidence: 99%

“…Some of the common bloom-forming algal species are illustrated in Figure 1.4. The size of which ranges from 2 µm to 2 mm, and the cell concentration range from 1,000 to 600,000 cells/mL (Villacorte et al, 2015b). Villacorte et al, 2014) Algal blooms increase the suspended solids concentration as well as the organic substances responsible for membrane fouling (Caron et al, 2010).…”

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Controlling Biofouling in Seawater Reverse Osmosis Membrane Systems

Dhakal¹

2017

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Although all care is taken to ensure the integrity and the quality of this publication and the information herein, no responsibility is assumed by the publishers, the author nor UNESCO-IHE for any damage to the property or persons as a result of the operation or use of this publication and/or the information contained herein. A pdf version of this work will be made available as Open Access via http://repository.tudelft.nl/ihe This version is licensed under the Creative Commons SummarySeawater reverse osmosis (SWRO) is the preferred technology of choice for seawater desalination. However, membrane fouling is a major challenge for the cost-effective operation of membrane based desalination systems. An emerging threat to SWRO is the occurrence of algal blooms and the associated high concentration of algal cells and algal organic matter (AOM) in seawater. To help minimize membrane fouling, SWRO systems are equipped with pre-treatment systems. However, current pre-treatment systems are not capable of removing all AOM from SWRO feed water. The AOM that passes from pretreatment systems accumulates on the SWRO membrane surfaces and acts as a "conditioning layer" and can initiate biofilm development in the presence of available nutrients (C, P) in RO feed water.One notable example was the severe red tide algal bloom in the Middle East in 2008-2009. During this period pre-treatment processes such as granular media filter (GMF) with coagulation suffered from rapid clogging and produced poor quality water for the downstream SWRO system (SDI >5). As a result, some SWRO desalination plants in the coastal areas of the region were forced to shut down to avoid irreversible fouling of their RO membranes. After this event, the application of low-pressure membranes such as microfiltration and ultra-filtration (MF/UF) have been considered as a more reliable pretreatment during algal blooms. Previous studies have shown that conventional UF membranes are also not capable of removing all organic matter (AOM) from SWRO feed water, and thus organic/biofouling in downstream SWRO could occur. Therefore, new pretreatment technologies that can remove AOM, as well as other nutrients (C, P) from SWRO feed water are needed to delay the onset of organic and/or biofouling in SWRO systems.Furthermore, better methods/tools are required to assess and improve pre-treatment processes in terms of their ability to reduce re-growth potential prior to SWRO membranes.The overall goal of this research was to assess the ability of conventional UF (150 kDa) and tight UF (10 kDa) either alone or in combination with phosphate removal technology (PRT TM ) to delay the onset of organic/biological fouling in SWRO feed water during algal blooms. The three main objectives of the research were; i) to better understand ultrafiltration membrane fouling and the root causes of poor backwashability of organic matter generated by different marine algal species, ii) to develop an improved method to viii measure bacterial regrowth potential (BRP) prior to SWRO membrane sy...

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Section: Comparison Of Fouling Potential Of Aom and Aom + Algal Cellsmentioning

confidence: 99%

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confidence: 99%

Controlling Biofouling in Seawater Reverse Osmosis Membrane Systems

Dhakal¹

2017

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“…Other than pretreatment design and operation, the design of a proper seawater intake system represents a significant amendment for future SWRO facilities to mitigate the effects of HABs [12][13][14]. Although a majority of current SWRO facilities operate with an open (surface water) intake system, the use of subsurface systems (wells and galleries) can significantly reduce the influent suspended solids, bacteria, dissolved organic carbon, and toxic/non-toxic algae present in the source water [69,70].…”

Section: Contribution Of the Studymentioning

confidence: 99%

“…Caron and co-workers [11] acknowledged two important impacts of HABs on desalination facilities: (1) complete removal of algal toxins; (2) increased demand on pretreatment for membrane fouling prevention. Besides the elevated biomass, algal blooms also contribute to excess organic matter and transparent exopolymer particles (TEP) that intensify the biofouling potential of SWRO membranes [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Algal Biotoxin Removal during SWRO Desalination through a Materials Flow Analysis

Manheim

Jiang

2017

Water

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Abstract:The operation of seawater reverse osmosis (SWRO) desalination facilities has become challenged by the increasing frequency and severity of harmful algal blooms (HABs). The efficiency of algal toxins removal during SWRO and pretreatment processes has critical human health implications. Therefore, a probabilistic materials flow analysis (pMFA) was developed to predict the removal of algal toxins in source water by various pretreatment configurations and operations during SWRO desalination. The results demonstrated that an appreciable quantity of toxins exists in the SWRO permeate (ng/L-µg/L levels), the backwash of pretreatment, and final brine rejects (µg/L-mg/L levels). Varying the pretreatment train configuration resulted in statistically significant differences in toxin removals, where higher removal efficiencies were evidenced in systems employing microfiltration/ultrafiltration (MF/UF) over granular media filtration (GMF). However, this performance depended on operational practices including coagulant addition and transmembrane pressures of MF/UF systems. Acute human health risks during lifetime exposure to algal toxins from ingestion of desalinated water were benign, with margins of safety ranging from 100 to 4000. This study highlights the importance of pretreatment steps during SWRO operation in the removal of algal toxins for managing marine HABs.

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“…Over the years, it is becoming more evident that microscopic algae are a major cause of operational problems in SWRO plants (Caron et al, 2010;Villacorte et al, 2015a). The adverse effect of algae on SWRO started to gain more attention during a severe "red tide" bloom incident in the Gulf of Oman in [2008][2009] (Figure 1).…”

Section: Introductionmentioning

confidence: 99%