Inorganic Fouling

Lin L-S, Johnston CT, Blatchley III ER (1999) Inorganic Fouling at Quartz Water Interfaces in Ultraviolet Photoreactors — II. Temporal and Spatial Distributions, Wat. 

Fig. 23. Visualization of membrane fouling by scanning electron microscopy (A) inorganic fouling dne to calcinm carbonate, calcium sulfate, silica, iron, barium and strontium sulfate (35,000x) (B) organic fonling dne to humic acid (35,000x) (C) flow channels in membrane fouled with biological growth.

Atkinson, A, Gerrard, A.F. and Harris, A, 1979, Development of additives to control inorganic fouling in industrial water systems, in Fouling - Science or Art Inst. Corr. Sci. and Tech., Inst. Chem. Engrs., University of Surrey. 

FouUng can be controlled by altering the operating conditions (see section 3.5.3 for critical flux and pressure), chemicals addition (see inorganic fouling section 3.5.2) or by pretreatment. In this section the focus is on pretreatment. 

Soaking in acid (e.g. HCl, H2SO4, or citric acid) for inorganic fouling... 

Jawor, A. and Hoek, E.M.V. 2009. Effects of feed water temperature on inorganic fouling of brackish water RO membranes, 235(1-3) 44—57. 

The pH of cooling water naturally increases due to evaporation. Sulfuric acid is added as required to control the pH at 6.5-7.0. An excursion of high pH (9-10) will cause a rapid increase in inorganic fouling deposits in the exchanger tubes. 

Shirazi, S., C. J. Lin, D. Chen, Inorganic Fouling of Pressure-Driven Membrane Processes—A Critical Review. Desalination, 2010,250(1), 236-248. 

Arkhangelsky, E., Wicaksana, R,Tang, C., Al-Rabiah, A.A., Al-Zahrani, S.M. Wang, R. (2012) Combined organic-inorganic fouling of forward osmosis hollow fiber membranes. Water Research, 46 (19), 6329-6338. 

Oil-soluble dispersants are widely used to alleviate both organic and inorganic fouling problems. The object is not to prevent the initial formation of coke nuclei and other insoluble particles in the stream, but to reduce their tendencies to agglomerate into larger precipitates that can settle out of the process stream and deposit on and in various places in the equipment. A test for effectiveness of materials as anti-foulants, based on their ability to disperse carbon black in hydrocarbons can be established. 

Inorganic fouling or scale formation at the membrane surface results from the increased concentration of one or more inorganic salts such as CaCOj, CaS04, 2H2O, and Ca3(P04)2 beyond their solubility limits and their ultimate precipitation onto the membranes [8]. 

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