Calibrating and Validating the MFI-UF Method to Measure Particulate Fouling in Reverse Osmosis.

This study aimed to calibrate and validate the MFI-UF method in order to ensure the accuracy of particulate fouling measurements in RO. Firstly, the MFI-UF calibration was examined using two solutions of standard particles (dextran and polystyrene). Two main criteria were investigated: (i) MFI-UF linearity with particle concentrations at both low and high ranges of fouling potential and (ii) the reproducibility of MFI-UF linearity.

Is Desalination a Solution to Freshwater Scarcity in Developing Countries?

Rapid population growth and urbanization are two main drivers for the over-abstraction of conventional freshwater resources in various parts of the world, which leads to the situation of water scarcity (per capita availability <1000 m3/year). Predictions based on the World Bank projected population data and the FAO AQUASTAT database for freshwater availability show that by 2050, 2 billion people living in 44 countries will likely suffer from water scarcity, of which 95% may live in developing countries. Among these, the countries that will likely be most strongly hit by water scarcity by 2050 are Uganda, Burundi, Nigeria, Somalia, Malawi, Eritrea, Ethiopia, Haiti, Tanzania, Niger, Zimbabwe, Afghanistan, Sudan, and Pakistan.

Foulant Identification and Performance Evaluation of Antiscalants in Increasing the Recovery of a Reverse Osmosis System Treating Anaerobic Groundwater.

The objectives of this study are to assess the performance of antiscalants in increasing the recovery (≥85%) of a reverse osmosis (RO) plant treating anaerobic groundwater (GW) in Kamerik (the Netherlands), and to identify scalants/foulant that may limit RO recovery. Five different commercially available antiscalants were compared on the basis of their manufacturer-recommended dose. Their ability to increase the recovery from 80% to a target of 85% was evaluated in pilot-scale measurements with anaerobic GW and in once-through lab-scale RO tests with synthetic (artificial) feedwater.

Comparing the bacterial growth potential of ultra-low nutrient drinking water assessed by growth tests based on flow cytometric intact cell count versus adenosine triphosphate.

The bacterial growth potential (BGP) of drinking water is widely assessed either by flow cytometric intact cell count (BGP) or adenosine triphosphate (BGP) based methods. Combining BGP and BGP measurements has been previously applied for various types of drinking water having high to low growth potential. However, this has not been applied for water with ultra-low nutrient content, such as remineralised RO permeate.

Assessing Pretreatment Effectiveness for Particulate, Organic and Biological Fouling in a Full-Scale SWRO Desalination Plant.

In this study, the removal of particulate, organic and biological fouling potential was investigated in the two-stage dual media filtration (DMF) pretreatment of a full-scale seawater reverse osmosis (SWRO) desalination plant. Moreover, the removal of fouling potential in two-stage DMF (DMF pretreatment) was compared with the removal in two-stage DMF installed after dissolved air floatation (DAF) (DAF-DMF pretreatment). For this purpose, the silt density index (SDI), modified fouling index (MFI), bacterial growth potential (BGP), organic fractions and microbial adenosine triphosphate (ATP) were monitored in the pretreatment processes of two full-scale SWRO plants.

Measuring Biofouling Potential in SWRO Plants with a Flow-Cytometry-Based Bacterial Growth Potential Method.

Measuring the bacterial growth potential of seawater reverse osmosis (SWRO) feed water is an issue that is receiving growing attention. This study developed and demonstrated the applicability of the flow-cytometry (FCM)-based bacterial growth potential (BGP) method to assess the biofouling potential in SWRO systems using natural microbial consortium. This method is relatively fast (2-3 days) compared to conventional bioassays.

Monitoring Biofouling Potential Using ATP-Based Bacterial Growth Potential in SWRO Pre-Treatment of a Full-Scale Plant.

Several potential growth methods have been developed to monitor biological/organic fouling potential in seawater reverse osmosis (SWRO), but to date the correlation between these methods and biofouling of SWRO has not been demonstrated. In this research, the relation between a new adenosine triphosphate (ATP)-based bacterial growth potential (BGP) test of SWRO feed water and SWRO membrane performance is investigated. For this purpose, the pre-treatment of a full-scale SWRO plant including dissolved air flotation (DAF) and two stage dual media filtration (DMF) was monitored for 5 months using BGP, orthophosphate, organic fractions by liquid chromatography coupled with organic carbon detection (LC-OCD), silt density index (SDI), and modified fouling index (MFI).

Multi-parametric assessment of biological stability of drinking water produced from groundwater: Reverse osmosis vs. conventional treatment.

Although water produced by reverse osmosis (RO) filtration has low bacterial growth potential (BGP), post-treatment of RO permeate, which is necessary prior to distribution and human consumption, needs to be examined because of the potential re-introduction of nutrients/contaminants. In this study, drinking water produced from anaerobic groundwater by RO and post-treatment (ion exchange, calcite contactors, and aeration) was compared with that produced by conventional treatment comprising (dry) sand filtration, pellet softening, rapid sand filtration, activated carbon filtration, and UV disinfection. The multi-parametric assessment of biological stability included bacterial quantification, nutrient concentration and composition as well as bacterial community composition and diversity.

Measuring Bacterial Growth Potential of Ultra-Low Nutrient Drinking Water Produced by Reverse Osmosis: Effect of Sample Pre-treatment and Bacterial Inoculum.

Measuring bacterial growth potential (BGP) involves sample pre-treatment and inoculation, both of which may introduce contaminants in ultra-low nutrient water (e.g., remineralized RO permeate).

Further developing the bacterial growth potential method for ultra-pure drinking water produced by remineralization of reverse osmosis permeate.

Ensuring the biological stability of drinking water is essential for modern drinking water supply. To understand and manage the biological stability, it is critical that the bacterial growth in drinking water can be measured. Nowadays, advance treatment technologies, such as reverse osmosis (RO), are increasingly applied in drinking water purification where the produced water is characterized by low levels of nutrients and cell counts.

Improved method for measuring transparent exopolymer particles (TEP) and their precursors in fresh and saline water.

Transparent exopolymer particles (TEP) and their precursors produced by phyto-/bacterio-planktons in fresh and marine aquatic environments are increasingly considered as a major contributor to organic/particulate and biological fouling in micro-/ultra-filtration and reverse osmosis membrane (RO) systems. However, currently established methods which are based on Alcian blue (AB) staining and spectrophotometric techniques do not measure TEP-precursors and have the tendency to overestimate concentration in brackish/saline water samples due to interference of salinity on AB staining. Here we propose a new semi-quantitative method which allows measurement of both TEP and their colloidal precursors without the interference of salinity.

Effect of coagulation on fouling potential and removal of algal organic matter in ultrafiltration pretreatment to seawater reverse osmosis.

This paper investigated the effect of coagulation on fouling potential and removal of algal organic matter (AOM) in seawater ultrafiltration (UF) systems. AOM harvested from a strain of bloom forming marine diatom, Chaetoceros affinis, was coagulated with ferric chloride under different coagulation modes and conditions. The effect of coagulation on fouling potential was determined with the Modified Fouling Index-Ultrafiltration (MFI-UF).

The fate of Transparent Exopolymer Particles (TEP) in integrated membrane systems: removal through pre-treatment processes and deposition on reverse osmosis membranes.

The abundance of Transparent Exopolymer Particles (TEP) in surface waters has been unnoticed for many years until recently as a potential foulant in reverse osmosis systems. Recent studies indicate that TEP may cause organic and biological fouling and may enhance particulate/colloidal fouling in reverse osmosis membranes. The presence of TEP was measured in the raw water, the pre-treatment processes and reverse osmosis (RO) systems of 6 integrated membrane installations.