Fouling cartridge filters

Upon start-up of new cartridge filters, the initial effluent should be sent to drain. This is necessary to prevent fouling of the RO... 

Cartridge filters should be inspected regularly during use to determine the extent of fouling of the filter. Filters should be replaced when the differential pressure across them reaches 5 psi or 2 weeks, whichever comes first. At worst, filters operating with relatively clean feed water (such as RO permeate or well water low in iron) should be replaced at least once per month to minimize biofouling risks. 

Check cartridge filters The cartridge prefilters should be checked biweekly for pressure drop across them and to be sure they are seated properly. High pressure drop means it is time to replace the filters. Improper seating of the filters will lead to particulates bypassing the filters and fouling or abrasion (and destruction) of the membranes. 

Cartridge filter replacement frequency, high replacement rates (every 2 weeks or less) could indicate a fouling problem. Low replacement rates (every 1 month or more) could lead to microbial fouling as microbes grow in the "old" cartridges. 

Particle unloading from cartridge filters due to high pressure drop leading to fouling of the membranes... 

Dechlorinated and softened water flows to the RO skid through a 5.0-nm (nominal pore size) cartridge filter. The cartridge filter removes resin fines, particles and complexed colloids necessary to protect the RO membranes from particulate fouling. The RO membranes are thin-film composite (TFC) polyamide RO membranes (20 cm diameter X 100 cm long spiral wound elements) with rejection 99%. 

Upon start-up of new cartridge filters, the initial effluent should be sent to drain. This is necessary to prevent fouling of the RO membranes with materials used in the manufacture of the cartridge filter media. For example, lubricants and emulsifiers are used in the manufacture of the strings used in string-wound cartridge filters. These materials can coat the RO membranes and foul them. In the case of polypropylene depth filters, phthalates are used in their manufacture. As little as 50 ppb of phthalate will irreversibly foul an RO membrane. ... 

Combining these techniques, they carried out cultivations for 250-350 h, and were able to repeatedly use the same cartridge (four times at least) without measurable deterioration in filtration efficiency. However, when perfusion rate and cell concentration in the bioreactor increased, fouling eventually occurred. Van Reis et al. [92] provided backpressure on the filtrate line to control filtrate rates and so to avoid too high initial filtration rates, which can cause rapid fouling. De la Broise et al. [99] compared the filter performance using membranes of different pore sizes (2 and 10 pm). In both cases partial retention of the produced IgM was observed and membranes had to be changed every 5 days, the... 

Various techniques can be used to reduce the loading of suspended solids, organics and microbes in feed water. These include physical processes such as media filtration, cartridge microfiltration and chemical treatments. Chemical addition enhances the filter-ability of the solids such as the addition of coagulants (Table 2.2). Foulants and their control strategies are addressed in Table 2.8. Since any traces of soHds and organics get removed in the first membrane modules in RO and NF systems, these materials typically foul the first stages of an RO/NF system (Table 2.9). Once deposited on the membranes. 

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