Fouling prevention

Chemical attack is often a result either of fouling prevention or cleaning in response to fouling. Chlorine and hypochlorite damage most RO and NF membranes, as do oxidants generally (see discussion of chlorine tolerance below). 

Foulant category Type Electric charge Tendency to Fouling prevention method... 

Fouling prevention under fast precipitating conditions... 

Dow Chemical Company, "Water Chemistry and Pretreatment Biological Fouling Prevention," form no. 609-02037-1004. 

Wakeman RJ and Tarleton ES, Membrane fouling prevention in crossflow microfiltration, Chem. Eng. Sci. 1987 42(4) 829-842. 

The most common methods of fouling prevention are wastewater pretreatment, the control of hydrodynamic conditions in the apparatus (low flux, high feed flowrates, turbulence promoting, dynamic filtration), or special construction of the module (cross-flow filtration). 

Huuhilo T. Fouling, prevention of fouling, and cleaning in filtration. PhD dissertation, Acta Universitatis Lappeenrantaensis, Lappeen-ranta University of technology, Lappeenranta, Finland. 

Various processes are available for pretreatment of membrane processes. These methods are either aimed at rejection enhancement or fouling prevention. The majority of the techniques target different compounds, and thus need to be tailored to a specific water and application. 

A German patent was issued to Edison in 1890. He set up a field between a ship s hull and electrodes hung overside. The ship was made negative in the electric circuit, and the method supposes that a fouling organism would avoid an electric field. There are no reports of the practical use of Edison s method of fouling prevention. 

An anodic method for fouling prevention would depend upon either the anodic production of a biocide, using an external source of chloride electrolyte, or the anodic production of toxic metal ions. 

Littauer and Jenningsexamined the cathodic electrolysis of seawater as a means of fouling prevention at various current densities, and obtained partial protection. However, at current densities greater than 1 mAcm , calcareous deposits formed on the electrode. 

An electrochemical method for fouling prevention could be effectively applied as the method works at the metal-electrolyte interface where the prevention is needed. Thus, an excess use of a chemical which is always necessary in the chemical mode of fouling prevention could be avoided in the electrochemical method. The method could be ideal for situations where biofouling has to be avoided at the earliest stage, for example, in an OTEC power plant. In some systems, it would be possible to prevent fouling and electrochemical corrosion simultaneously by a proper manipulation of the cathodic potential. 

Maartens, A., Jacobs, E.P. and Swart, P. 2002. UF of pulp and paper effluent Membrane fouling-prevention and cleaning. 209 81-92. 

Heat exchanger fouling costs a lot of money for process plants. It is essential to determine the root causes and find appropriate methods for fouling mitigation from fouling prevention to exchanger cleaning cycle optimization. 

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