Operational fouling control

The interaction between all these parameters is largely unknown. As these factors can be controlled by operational measures, operational fouling control will be discussed in greater detail next. 

Fouling is controlled by selection of proper membrane materials, pretreatment of feed and membrane, and operating conditions. Control and removal of fouling films is essential for industrial ultrafiltration processes. 

Membrane fouling is the main cause of permeant flux decline and loss of product quality in reverse osmosis systems, so fouling control dominates reverse osmosis system design and operation. The cause and prevention of fouling depend greatly on the feed water being treated, and appropriate control procedures must be... 

Ultrafiltration Reliability (fouling) Cost Selectivity Fouling remains the principal operational problem of ultrafiltration. Current fouling control techniques are a substantial portion of process costs... 

The performance of a membrane process is a function of the intrinsic properties of the membrane, the imposed operating and hydrodynamic conditions, and the namre of the feed. This chapter describes methods available to enhance performance by various techniques, mainly hydrodynamic but also chemical and physical. The focus is on the liquid-based membrane processes where performance is characterized by attainable flux, fouling control, and separation capabilities. The techniques discussed include secondary flows, flow channel spacers, pulsed flow, two-phase flow, high shear devices, electromagnetic effects, and ultrasound. 

In general, the major problem in heat exchanger operation is the accumulation of deposits on surfaces. To avoid taking the exchanger out of service for cleaning, on-line fouling control is often employed. The choice of method will, of course, very much depend on the fouling problem encountered. There are two basic methods control may be achieved by the use of chemical additives and by physical methods, or in some instances, with a combination of the two. 

Incidents of corrosion and fouling were only included if a feature unique to the column design, operation, or control contributed to their occurrence. For instance, tales of accelerated corrosion due to liquid maldistribution, or poor removal of water from a hydrocarbon column, constitute "columns that did not work. On the other hand, an incident where the wrong corrosion inhibitor was applied or a pH controller malfunctioned is related to handling the chemicals rather than to the column it would have occurred in any other piece of equipment processing the chemicals it therefore does not constitute a "column that did not work. ... 

In MBR, membrane fouling can be affected by the nature of the feed, the membrane properties and the hydrodynamic or operating conditions [4]. Better understanding of those interactions is necessary to implement more efficient fouling control and removal strategies. A brief summary of recent research conducted in the MBR field may also allow us to further comprehend the chemical and physical natures of the fouling layer we aim to observe with the different techniques introduced later in this chapter. 

The design of a polymerization reactor begins with the selection of the type of reactor (batch, semibatch or continuous) and then proceeds to the sizing and details of the reactor configuration. Only then can the details of operation and control be addressed. To this end, we will begin with a discussion of the basic types of reactors. Ultimately, it will be clear that the choice of reactor type is determined not only by practical considerations such as scale of production and propensity for fouling, but also by the specific polymerization kinetics. More complete discussions of reactor types and their residence time distributions may be found in references [1,2],... 

Fouling control in submerged modules is achieved by coarse bubble aeration. (External) horizontal modules are operated in the side-stream mode. Most systems are relaxed periodically some can be back pulsed (at very low pressure). A schematic view is depicted in Figure 9.3. 

Lower energy demand as operational issues (flux, fouling control) are optimized. 

Elimelech 2004 Religa et al. 2013 Simon et al. 2013). However, the deterioration of membrane structures due to the acidic or alkaline solution can greatly shorten the membrane lifespan. The ability of the polymeric membrane to withstand an extreme pH condition will definitely determine the life expectancy of the membrane in certain applications. In addition, fouling control of polymeric membranes, through either operating condition adjustment or membrane material selection, is important in order for the wider employment of NF processes to become feasible. 

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