Organic fouling

Organic fouling depends on the organic characteristics. Research to date focuses on the identification of a critical organic fraction, which then can be eliminated to prevent fouling. 

Once again the above results emphasise the importance of solute-solute interactions. Membrane characteristics and operating conditions also affect fouling. 

Inorganic ions enhance fouling during water treatment with membranes. In the NF of conventionally treated water, the adsorption of macromolecules was followed by the adhesion of a biofilm. The inorganic deposit was determined to be mainly calcium, phosphorus (due to pretreatment), and 

Calcium can be expected to create a more compact fouling layer and thus enhance flux decline. Malleviallc et al (1989) used various ME and UF membranes to evaluate the irreversible fouling of HS. Flux decreases of up to 90% were observed in the initial stages of filtration. An analytical scheme to analyse water and the deposit was established. Fouling could be linked to the organic matrix of HS, and carbohydrates, proteins, and polyhydroxy aromatic compounds were believed to be the major contributors. 

Yuan and Zydney (1999) found that humic substances, despite their small size, can cause a significant flux decline of MF membranes. This was attributed to aggregates deposited on the membrane surface. Prefiltration improved flux decline, but reaggregation occurred at increased calcium concentrations. An initial deposit of organics facilitated further deposition. 

---

Amberlite IRA-458 1.2 1.08 Has an acrylic structure rather than S-DVB hence more hydrophilic and resistant to organic fouling. 

Amberlite IRA-93 1.3 1.04 Styrene-DVB pH range is 0 to 9. Excellent resistance to oxidation and organic foul-... 

A further problem that may cause contamination of the treated MU water is anion leakage as a result of organic fouling. This significantly affects anion resins, preventing ion removal by ion exchange and thus reducing bed capacity. 

Organic fouling also affects cation resins, albeit to a lesser degree. The fouling primarily stems from the attachment to the anion exchange site of a variety of low-level organic matter of variable molecular weight that is present in the raw water source. 

Organic fouling of DI resins. Loss of treated water capacity Anion leakage... 

Type 1 and 2 resins Refers to SBA resins. Type 1 resins are either standard (particularly good temperature and oxidation stability) or porous (higher capacity and resistance against organic fouling). The structure of type 2 resins is similar to type 1 but provides for maximum capacity and resistance to fouling. 

Removal of general organic fouling is best achieved by alkaline cleaning based on caustic, EDTA, and a surfactant such as sodium dodecyl sulfate or sodium lauryl sulfate. 

Although EDI may be used as a process for the production of basic pure water, in practice it suffers from the organic fouling potential of resins and the scale fouling potential of ED when higher TDS water sources are utilized. Appropriate pretreatment is therefore required. As a consequence, EDI is best suited for the production of very pure and ultrapure water by acting as a polisher to follow bulk water deionization by RO. Under these circumstances, it competes with both doublepass RO and MB units. 

Animal uptake, of herbicides, 23 310 Animal viruses, 3 135-136 Animal waxes, 26 203, 206 Anion binding, in supramolecular chemistry, 24 43-47 Anion-exchange membranes, 15 836 Anion exchangers, organic fouling of, 24 416... 

Watkins, E.J. and Pfromm, P.H. 1999. Capacitance spectroscopy to characterize organic fouling of electrodialysis membranes. J. Membr. Sci. 162, 213-218. 

Organic fouling is the attachment of materials such as oil or grease onto the membrane surface. Such fouling may occur accidentally in municipal drinking... 

Organic fouling is the basis ofbiofouling, which is one of the most severe problems seeking a solution [40-43]. Currently, only good pretreatment may limit biofouling. 

Li, Qilin, and Menachem Elimelech, "Organic Fouling and Chemical Cleaning of Nanofiltration Membranes Measurements and Mechanisms," volume 38, number 17,2004. 

Sulfate scale Organic Fouling Biofouling Silica... 

---