Submerged membranes cleaning

This is because the entire tank containing the submerged membrane cartridge must be filled with chemical to clean the membranes (note that spacers are used to occupy space to minimize this factor). 

Submerged membranes are operated with the feed in a vessel at atmospheric pressure. To obtain a TMP, the permeate side has to be below atmospheric pressure, and this is achieved by suction provided by permeate pumping. The pressure on the permeate side will be determined by the TMP defined by Eq. (10.3) as well as a presstrre drop due to permeatc-side (lumen) flow, which may be significant for hollow fibers. This situation has been analyzed for vertical submerged hollow fibers closed at the bottom and with suction at the top. The situation is depicted in Figure 10.18a for a clean water feed, and the axial flux distribution can be estimated from (Chang et al., 2000)... 

PRACTICAL ASPECTS 265 TABLE 10.4 Cleaning Methods Typically Used with Submerged Membranes ... 

After the desired period of incubation, fix the embryo by flooding with methanol (for most immunological detection procedures), Zenker s fixative (for Feulgen-Rossenbeck staining), or in 4% formaldehyde in PBS (for in-situ hybridization and most other procedures). In the case of methanol or Zenker s, which are rapid fixatives, it is advantageous to submerge the cultured embryo in saline, then detach it from the vitelline membrane and transfer it to a clean dish with saline prior to fixation. Otherwise, the embryo adheres permanently to the membrane and the fixative denatures the albumen, generating threads of protein that tend to stick to the embryo. Formaldehyde can be poured directly onto the embryo, provided that the embryo is detached from the membrane within a few minutes. 

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