Modified Fouling Index Research Articles

Ultrafiltration of Coagulation-Pretreated Serratia marcescens Fermentation Broth: Flux Characteristics and Prodigiosin Recovery

The dead-end ultrafiltration (UF) of coagulation-pretreated fermentation broth of Serratia marcescens SMΔR for prodigiosin recovery was studied. Experiments were performed using different types (regenerated cellulose, YM; polyethersulfone, PES) and molecular weight cut-offs (MWCOs, 1–10 kDa) of the membranes, feed concentrations of prodigiosin (300–1000 mg/L), applied pressures (68.9–206.8 kPa), and stirring speeds (200–400 rpm). With the same MWCO, the YM membrane had a higher retention of prodigiosin and a lower flux than the PES membrane. A two-fold concentration of prodigiosin was observed in the retentate using a 1-kDa YM membrane compared to the concentration in the permeate using a 10-kDa YM membrane. In addition, the extent of membrane fouling was quantitatively analyzed in terms of the modified fouling index. Flux decline in the present batch UF process was mainly due to cake layer formation and partly due to pore blocking. A two-stage UF process was proposed for this purpose, with 81% recovery yield and four-fold concentration.

Effect of Extracellular Polymeric Substances on Operation of Membrane Bioreactor

In order to study the relationship between extracellular polymeric substances (EPS) and membrane fouling, the effect of extracellular polymeric substances (EPS) on the operation of membrane bioreactor (MBR) was investigated in this paper. The operation of membrane was analyzed by evaluating sludge volume index (SVI), modified fouling index (MFI), and membrane resistance (Rt), respectively. The results showed that SVI, MFI, and Rt increased with the accumulation of EPS, and membrane fouling aggravated with the increase of EPS, this illustrated that the content of EPS had a direct influence on SVI, MFI, Rt and membrane fouling. The consequences could offer a simple method to monitor the concentration of EPS by analyzing SVI, MFI, or Rt.

SDI: is it a reliable fouling index?

The ASTM considers the silt density index (SDI) test as a standard test for fouling potential of RO and NF feed waters. Up to date, the SDI is used at many full- and pilot-scale installations. The design and choice of the applied RO pretreatment is to a large extent based on the SDI test on the raw feed water. Comparing and monitoring UF/MF membrane performance is another SDI application. From a practical point of view, the SDI of RO feed water preferably should be lower than 3. The SDI has several disadvantages making it an unreliable test. The SDI has a non linear relationship with the colloidal concentration in the water and it is not corrected for the feed water temperature. Besides that, the SDI is not based on any filtration model. SDI is trying to simulate the RO fouling using dead-end MF membrane. The modified fouling index (MFI) is another fouling index. The MFI is based on the cake filtration model, can be corrected for pressure and temperature and is therefore used as a promising alternative for the SDI. Nevertheless, the procedure of measuring a MFI is more difficult and not directly suitable for carrying out “in the field”. The objective of this study therefore is to determine a theoretical relationship between SDI and MFI, and to validate this with experimental results. This relationship can be used to investigate the influence of membrane and testing parameters on SDI under cake filtration conditions, implying this model is valid for cake filtration mechanism and a particle rejection of 100%. In order to calculate the SDI, the times t 1 and t 2 for collecting the first and second sample are predicted using the measured MFI value and the MFI definition. In this research, the influence of several parameters (such as temperature, membrane resistance, etc.) on the SDI will be shown. The experimental results show a good agreement with the theoretical work, but only if the cake filtration start builds up directly at the beginning of the experiment. In general, this work clearly demonstrates that SDI currently is not reliable test for RO fouling. Either corrections for the SDI are necessary to give a more reliable index, or a new index has to be developed.

Flux dependency of particulate/colloidal fouling in seawater reverse osmosis systems

Abstract Fouling is the main operational problem in seawater reverse osmosis systems (SWRO). Particulate fouling is traditionally measured through the silt density index (SDI) and through the modified fouling index (MFI). In recent years, ultrafiltration membranes were used successfully at constant flux – MFI-UF – to measure particulate/colloidal fouling potential and tested in sea water applications. Furthermore, constant flux operation allows predicting the rate of fouling in RO systems. The objectives of this study are: (1) to measure the flux effect in MFI-UF with different membranes (100, 30 and 10 kDa) for raw seawater and pre-treated water before reverse osmosis in three different locations; (2) to study the particulate and colloidal fouling potential of seawater in reverse osmosis systems; (3) to project the increase in pressure due to cake resistance in reverse osmosis systems. In this research, flat ultrafiltration membranes (100, 50, 30 and 10 kDa) are used in a constant flux filtration mode to test and compare real seawaters from various locations (North and Mediterranean Sea) and from various full scale facilities including different pre-treatments (i.e., ultrafiltration and coagulation + dual media filtration). The operated fluxes range from 350 down to values close to real RO operation, 15l (m2 h)−1. After each filtration test, the MFI-UF is calculated to assess the particulate fouling potential. The obtained results showed that: (1) the articulate and colloidal fouling potential is directly proportional to the applied flux during filtration. This proportionality is related to the compression of the cake deposit occurring at high flux values; (2) the higher the flux, the higher the required pressure, the less porous the cake and therefore the higher the specific cake resistance; (3) particulate and colloidal fouling potential of seawater is site specific and is influenced by pre-treatment.

Filtration demonstration plant as reverse osmosis pretreatment in an industrial water treatment plant

Reverse osmosis (RO) has emerged as an alternative treatment in industrial water production. However, RO systems need suitable pretreatment to avoid membranes fouling. A demonstration study was conducted to assess improvements to RO pretreatment in the water treatment plant of a steel factory. Various pretreatment options, resulting from the combination of the existing treatment with different filtration stages, were tested. The silt density index (SDI) and the modified fouling index (MFI) were used to evaluate the performance of the different configurations. Throughout the experimentation period, it was not possible to assess the SDI of the filtration inlet water due to the high colloidal fouling, while the inlet MFI ranged from 9 to 458. Results showed that the dual-stage in-series filtration, including two pressurized filters, provided the best results, achieving SDI values lower than 5 and effluent MFI values lower than 1 under optimized operating conditions. Considering the fact that the MFI is a more accurate measurement as it takes into account the cake filtration mechanism, we conclude this configuration was able to provide enhanced RO pretreatment with a higher quality than the minimum required, despite the SDI not being lower than 3 with a reliability of 90%.

Syndrome de Graham-Little-Lassueur associé à des anticorps anti-envoplakine

Removal of chromate from wastewater was investigated using Micellar Enhanced Crossflow Microfiltration Technique (MEMF) with cationic surfactant, cetyltrimetylammoniumbromide (CTAB). The variation of chromate, surfactant rejections and permeate flux with time were measured at two different CTAB concentrations as a function of transmembrane pressure drop (ΔP) and crossflow velocity, while CTAB/chromate, membrane pore size, temperature and pH of the feed solution was kept constant. For low CTAB concentration, it was observed that the efficiencies of chromate and surfactant removal increased with increasing ΔP, but decreased with increasing crossflow velocities. It was also observed that the effects of crossflow velocities and ΔPs on the rejections decreased for high CTAB concentration. It was found that fouling of the membrane by surfactant is very rapid at low crossflow velocity and high ΔPs at low CTAB concentration. As a result of this case, both transient permeate flux (J) and steady state permeate flux (J⁎) decreased with decreasing crossflow velocity and increasing ΔP for both CTAB concentration. Unlike, modified fouling index (MFI) values increase with decreasing crossflow velocity and increasing ΔP. It was also observed that the effect of surfactant concentration in the 150, 200, and 250 kPa pressure and 3, 4, and 5 m/s crossflow velocity intervals dominates at high surfactant concentration.

The influence of membrane and water properties on fouling during ultrafiltration

Membrane techniques are an alternative for classical processes of water treatment. However, one of their main drawbacks is that their capacity and membrane lifetime are limited by the phenomenon termed fouling. Natural organic matter (NOM) has been reported as the main foulant during water ultrafiltration. The character of NOM fouling depends on many factors. The results of the study on the effect of water properties such as pH, kind of foulant and ionic strength on the extent of membrane fouling are discussed in this article. Membranes used in the experiment vary in contact angle. Unified Modified Fouling Index (UMFI) was used to describe the intensity of fouling during ultrafiltration. The investigations was made with the use of the Ultrafiltration Cell Millipore CDS10 System. The device was equipped with flat sheet membranes and was operated in the dead-end mode. The study showed that the increase of ionic strength and pH resulted in the decrease of fouling. It was also found that the most severe fouli...

Improving Fouling Indices Measurements and Modeling Their Relevance

Reliable methods to predict feedwater fouling potential are important in preventing and diagnosing fouling at the design and operation stages of ultrafiltration (UF) and reverse osmosis (RO) plants, as well as monitoring pretreatment performance during operation. The desalination industry uses the silt density index (SDI) extensively to characterize feedwater fouling tendency. However, SDI measurements commonly lack the required precision, especially for high-quality pretreated waters, such as UF permeates. A novel performance model predicted how much transmembrane and feed-brine fouling will occur in the RO stage of a desalination plant based on SDI and modified fouling index (MFI) results. The SDI and MFI observations can now be translated into enhanced parameters that describe how much transmembrane and feed-brine resistance would be created by a certain fraction of water passing through the membrane. This article describes developments in the equipment and methodology used to measure fouling tendency of RO feedwater. Recommendations regarding the testing equipment and procedures are also provided.

SDI normalization and alternatives

Estimating the fouling potential is a prerequisite for controlling membrane fouling in reverse osmosis systems. Two different tests are routinely used to that end: the Silt Density Index (SDI) and the Modified Fouling Index (MFI0.45). SDI test, however, has disadvantages which make it unreliable. One disadvantage is that no linear relationship exists between SDI and the colloidal concentration in the water. Besides that, the SDI is not based on a filtration model. Finally, the SDI is not corrected for the testing condition parameters such as temperature, pressure and membrane properties. The SDI test is simple and does not require advanced professional skills, but the above mentioned disadvantages make it unreliable. This work offers practical tools to resolve these disadvantages, such as a slide tool to calculate the SDI from the measured collection times. It also proposes a normalized SDI (SDI +), and offers a line chart and slide wheel charts for this conversion, thus correcting for different test conditions and membrane resistance. Finally, this paper introduces a new fouling index. This volume-based SDI, SDI_v, compares the initial flow rate with the flow rate after filtering the standard volume. It has a linear relationship to the particle concentration if complete blocking is the dominant fouling mechanism during the test, and is independent of testing conditions and membrane resistance. The mathematical model and experimental results show that SDI_v eliminates most of the disadvantages of the traditional SDI. The SDI_v is the second fouling index developed at the University of Twente, 30 years after the MFI0.45.

Submerged membrane coagulation hybrid system as pretreatment to organic matter removal from seawater

In this study, a commonly used ferric chloride was utilised as coagulant for removing organic compounds from seawater. More than 57% of dissolved organic carbon (DOC) was removed at optimum dosage of 3 mg Fe+3/L. The coagulation by FeCl3 at optimum dosage could remove a majority (95%) of hydrophobic compounds. The results from Liquid Chromatography – Organic Carbon Detector showed that only <0.02 mg/L of hydrophobic compounds was found after coagulation. In addition, the modified fouling index decreased considerably from 15,848 s/L2 with raw seawater to 3,025 s/L2 with seawater after coagulation. In-line coagulation coupled with submerged membrane system (ICSMS) was also trialled. It is observed that critical flux was increased from 20 L/m2·h in the conventional submerged membrane system to 55 L/m2 h in ICSMS. The ICSMS could remain the high DOC removal efficiency (more than 70%) at filtration rate of 20 L/m2 h when keeping the development of trans-membrane pressure was significant lower than that of conventional submerged membrane system.

Assessment of water treatment processes: detailed organic matter characterisation and membrane fouling indices at the Loddon Water Treatment Plant, Victoria, Australia

Recent advances in membrane technology have led to its broad application, and reverse osmosis (RO) systems now represent the fastest growing segment of the desalination market. Its performance is hindered by membrane fouling. In this study pre-treatment methods to reduce RO fouling were investigated including flocculation, adsorption and ion exchange. Detailed organic characterisations were made in terms of florescence spectroscopy excitation emission matrix (EEM), UV254 absorbance and liquid chromatography-organic carbon detection (LCOCD). The different pre-treatment methods were assessed in terms of the fouling potential. This was quantified in terms of the modified fouling index measured using a dead-end cell micro-filtration (MF) unit. The existing pre-treatment of granular activated carbon (GAC) filter led to a good organic removal. Among the pre-treatment methods tested in the laboratory, purolite ion exchange/adsorption was found to be better than FeCl3 flocculation in terms of the amount as well as the wide range of organics removal. A pre-treatment of flocculation with Poly-ferric-silicate (PFSi) as flocculent gave a higher removal of organic matter compared to other pre-treatments tested. DOC was reduced from 11.5 to 4.25 mg/L, and it removed mostly the humic type substances.

Silt Density Index and Modified Fouling Index relation, and effect of pressure, temperature and membrane resistance

Particulate matter present in feed water of reverse osmosis and nanofiltration membrane elements tends to deposit on the membrane surface and spacers. This type of fouling results in permeate flux decline, loss of product quality and membrane damage. To characterize the fouling potential of RO feed water the Silt Density Index (SDI) and the Modified Fouling Index (MFI0.45) are commonly applied. SDI is applied worldwide for many years on a routine basis by operators since it is a simple and cheap test. Unfortunately, the SDI has several deficiencies e.g. it is not based on any filtration mechanism, has no linear relation with particulate matter and is not corrected for temperature, pressure and membrane resistance. This might explain the frequently reported erratic results obtained in practice, e.g. water treated with ultrafiltration showed in several cases high SDI values, which could not be attributed to failures of the UF membrane elements or systems. To overcome these deficiencies the MFI0.45 has been developed. This test is based on the occurrence of cake filtration during a substantial part of the test, has a linear relation with particulate matter content, and is corrected for pressure and temperature. However the manual procedure of measuring an MFI0.45 is somewhat more complicated and for this reason less suitable for application on a routine basis in practice. Fully automated equipment, measuring SDI and MFI0.45 at the same time is on the market. In this study a mathematical relation between SDI and MFI0.45 has been successfully developed, assuming that cake filtration is the dominant filtration mechanism during the tests. Based on the developed mathematical relation and experiments with an artificial colloidal suspension of aluminum oxide spheres (0.6 μm) as model water, it could be demonstrated that the SDI depends on pressure, temperature and membrane resistance. The effect of temperature and membrane resistance explains to a large extent the erratic results from the field. It is recommended to correcting SDI for temperature and membrane resistance and/or to making the guideline formulated by ASTM for the allowable range of membrane resistances much more stringent.

Hybrid filtration method for pre-treatment of stormwater

In this study the hybrid filtration process (combining fibre filter with deep bed dual media filtration) was investigated as pre-treatment to stormwater. This process was investigated in-terms of reduction in turbidity, dissolved organic carbon (DOC), colour, headloss development across the filters, suspended solids removal, organic matter removal, nutrients and heavy matter (such as iron, copper, lead, zinc) removal efficiency. A comparison was made between the hybrid filter with single media (sand) deep bed filter and fibre filter. It was found that the hybrid filtration system successfully removed turbidity (98%), colour (99%), suspended solids (99%), and DOC (55%). The removal efficiency of heavy metal was relatively low as the concentration of heavy metals present in stormwater was low. The removal efficiency of nitrate, nitrite and phosphorous (as orthophosphate) was 27, 35 and 72% respectively. Hybrid filtration processes showed a better reduction of Modified Fouling Index (MFI) value (from 15.500 s/l(2) to 9 s/l(2)) compared with single media sand, anthracite and fibre filter which were 35 s/l(2), 13 s/l(2)and 14 s/l(2) respectively when operated at FeCl(3) dose of 15 mg/l.

Evaluation of membrane fouling potential by multiple membrane array system (MMAS): Measurements and applications

A new approach to evaluate the fouling potential of feed waters for reverse osmosis (RO) and nanofiltration (NF) practices was systematically investigated. A multiple membrane array system (MMAS) was developed, in which microfiltration (MF), ultrafiltration (UF), and nanofiltration (NF) membranes were connected in series. This system was designed to separate the target foulants in the feed water and evaluate the fouling potential of a targeted foulant. More specifically, particulate, colloids, and organic matters were separated by MF, UF, and NF membranes in a consecutive manner, and the modified fouling index (MFI) was measured during each separation. The resulting three MFI values are Particle-MFI, Colloid-MFI, and Organic-MFI, and presented schematically in a triangle manner. The results demonstrated that fouling potentials of various feed waters (e.g., seawaters pretreated by various pretreatment options as well as raw seawater) evaluated by the MMAS were much more accurate and informative compared to those predicted by conventional silt density index (SDI) and single MFI. The fouling potentials determined by the MMAS precisely reflected changes in feed water quality by different pretreatment options (i.e., sand filtration, microfiltration, and ultrafiltration), while SDI measurements were not sensitive enough to detect these variations. It was also shown that the fouling potentials evaluated by the MMAS were well correlated with the actual flux-decline rates determined by lab-scale RO fouling experiments simulating seawater desalination, suggesting that the MMAS could provide a better way to predict fouling potential and guidance to select proper pretreatment processes.

Crossflow Sampler Modified Fouling Index Ultrafiltration (CFS-MFI UF)—An alternative Fouling Index

A Fouling Index known as the Crossflow Sampler Modified Fouling Index Ultrafiltration (CFS-MFI UF) measured under constant flux is developed in this paper. The method involves a specially designed crossflow cell, the permeate of which flows to a dead-end MFI measuring device. This method has both the capability of capturing small foulant particles as well as simulating the crossflow hydrodynamic conditions of an reverse osmosis (RO) module. The traditional fouling indices, such as MFI, are measured using dead-end filtration and the crossflow hydrodynamic conditions in actual RO membrane filtration are not taken into account. In the current study, colloidal silica and humic acid were selected as representatives of a colloidal foulant and macromolecular foulant, respectively. When humic acid was added to the silica colloids, CFS-MFI UF was found to have a linear relationship with the humics concentration, suggesting that CFS-MFI UF is not only sensitive toward colloids, but also to organic matter. In all of the experiments, CFS-MFI UF was compared with the Modified Fouling Index Ultrafiltration constant flux (MFI-UF const.flux). The results indicated that the conventional MFI-UF const.flux tends to predict a higher fouling propensity by 10–40% when compared to the CFS-MFI UF. CFS-MFI UF was also tested using seawater and pre-filtered seawater. The CFS-MFI UF shows significant improvement after pre-treatment, but this improvement cannot be detected by MFI-UF const.flux. Preliminary RO experiments with silica and humic acid mixture solution indicated that CFS-MFI UF was more sensitive to fouling propensity. The CFS-MFI UF predicted transmembrane pressure (TMP) profile agreed well with the actual RO fouling behaviour with only 11% deviation in the absence of salt. While with the salt in the solution, TMP profile predicted based on CFS-MFI UF plus osmosis pressure due to salt alone is unable to match the actual RO fouling behaviour. This indicates the potential contribution of cake enhanced osmosis pressure in RO fouling.

Impact of molecular weight distribution of soluble microbial products on fouling in membrane bioreactors

The molecular weight (MW) distributions of soluble microbial products (SMPs) were measured in membrane bioreactors (MBRs) using membranes with nominal molecular weight cut-offs of 1, 10 and 100 kDa to investigate the impact of each of the fractions, i.e. >100, 10–100, 1–10, and <1 kDa on fouling in MBRs. Total SMPs were measured by summation of carbohydrate and protein SMP. Mixed liquor and its components (soluble and suspended solids) were analyzed for their filtration resistance, as reflected by the modified fouling index (MFI). The results showed that there was no correlation between fractions of >100 kDa and 1–10 kDa and fouling in MBRs. However, there was a strong correlation between fouling and SMP concentration in the range of 10–100 kDa with higher fouling rates associated with higher concentrations of 10–100 kDa fraction.. Statistical analysis also proved that the SMP fraction 10–100 kDa is the most important fraction from a fouling perspective. Furthermore, fouling was found to decrease by increasing the <1 kDa fraction of SMP which was confirmed with the results of statistical analysis indicating a negative correlation between the fraction <1 kDa and the fouling rate.

Investigating submerged ultrafiltration (UF) and microfiltration (MF) membranes for seawater pre-treatment dedicated to total removal of undesirable micro-algae

In this study, an original use of low-energy-consuming submerged MF/UF membranes was investigated for the total removal of toxic micro-algae ( Alexandrium sp.) from seawater. Experimentally, a non-toxic micro-alga ( Heterocapsa triquetra) which has morphological and dimensional (15–20 µm) similarities with Alexandrium sp., one of the smallest toxic micro-algae in seawater, was ultra- and micro-filtered. A lab-scale membrane screening was operated on 10 kDa, 300 kDa and 0.2 µm membranes by filtration of 30,000 cells mL − 1 of H. triquetra suspension (equivalent to a major natural phytoplanktonic bloom). The most promising results were obtained with microfiltration membrane (0.2 µm): the highest steady state permeate flux reached 29 L h − 1 m − 2 under 0.3 bar of transmembrane pressure after 180 min of filtration. More than 99%, 87% and 98% of micro-algae, Total Suspended Solid (TSS), and turbidity were eliminated, respectively. Combining hydraulic permeability versus time with modified fouling index (MFI) determination and membrane autopsy (FEG-SEM and AFM observations), it is observed that fouling is mainly due to cake formation.

Deep bed filter as pre-treatment to stormwater

This paper presents the results of experiments on the application of dual media and single media deep bed filters as pre-treatments to stormwater. In-line flocculation-filtration experiments were conducted with dual and single media filter. The single filter media (80 cm) consisted of either anthracite or sand, and the dual media filter consisted of sand (40 cm at the bottom) and anthracite (40 cm on top). Filtration velocities of 5 m/h, 10 m/h and 15 m/h were examined. The removal efficiency for turbidity, suspended solids and TOC was found to be 95%, 99% and 30–45% respectively at a flocculant dose of FeCl3 of 15 mg/L. The anthracite filter media showed a lower headloss development (26 cm, operated at 5 m/h filtration velocity with FeCl3 dose of 5 mg/L). The removal efficiency for nitrogen was lower than phosphorus which was relatively good (up to 50%). The removal efficiency for heavy metals such as Cd, Pb, Cr and Ni was found to be very low for all tested filtration systems because concentrations of these metals in the influent were also low. This filter can be used as a pretreatment to a membrane filter as the modified fouling index was reduced from 750 s/L2 (for stormwater) to 15 s/L2 (for filtered effluent). Detailed submerged membrane filter experiments conducted with pre-treated water showed that the membrane filter can be successfully be used as post-treatment to in-line flocculant-filter at a sustainable flux of 10 L/m2.h to remove the remaining solids and pathogens. An increase of air scouring in the membrane unit decreased the pressure development although it did not have any effect on increasing the critical flux beyond 10 L/m2.h.

Treatment of Stormwater using Fibre Filter Media

In this study, a high-rate fibre filter was used as a pre-treatment to stormwater in conjunction with in-line flocculation. The effect of operating the fibre filter with different packing densities (105, 115 and 125 kg/m3) and filtration velocities (20, 40, 60 m/h) with and without in-line flocculation was investigated. In-line flocculation was provided using 5, 10 and 15 mg/L of ferric chloride (FeCl3·6H2O). The filter performance was studied in terms of pressure drop (ΔP), solids removal efficiency, heavy metals (total) removal efficiency and total organic carbon (TOC) removal efficiency. It is found that the use of in-line flocculation at a dose of 15 mg/L improved the performance of fibre filter as measured by turbidity removal (95%), total suspended solids reduction (98%), colour removal efficiency (99%), TOC removal (reduced by 30–40 %) and total coliform removal (93%). The modified fouling index reduced from 750–950 to 12 s/L2 proving that fibre filter can be an excellent pre-treatment to membrane filtration that may be consider as post-treatment. The removal efficiency of heavy metal was variable as their concentration in raw water was small. Even though the concentration of some of these metals such as iron, aluminium, copper and zinc were reduced, others like nickel, chromium and cadmium showed lower removal rates.

Submerged microfiltration coupled with physcio-chemical processes as pretreatment to sea water desalination

In this study, the critical flux of the submerged membrane system was experimentally evaluated when it was used for seawater with and without pre-treatment. In this study, different processes such as flocculation with ferric chloride (FeCl3) and different doses of PAC adsorption were used as a pre-treatment. The pretreatment of flocculant of 2 mg/L of FeCl3 and adsorption with the dose of 1 g/L PAC showed an improvement in the critical flux from 5 L/m2.h to 6.7 L/m2.h and 13.3 L/m2.h respectively. The performance of these pretreatments was also determined in terms of modified fouling index using ultrafilter membrane (UF-MFI). UF-MFI and SDI indicated that PAC adsorption was a better pretreatment than flocculation for the seawater used in this study. Molecular weight distribution (MWD) of seawater organic matter was also examined after different pretreatments. MWD of the raw seawater was mainly in the range from 1510 to 130 Da. It is observed that FeCl3 flocculation and PAC adsorption as pretreatments partially removed the organic matter of 1510 Da and 130Da respectively.