Rejection composite effluent

Figure 11. Rejections in terms of analysis for dye range composite effluent...

The complex formed when a mordant dyeing is aftertreated in a dichromate solution is retained by the wool in preference to the unmetallised mordant dye, which may desorb to some extent during the treatment. The latter is rather unstable in an oxidising solution and quinonoid by-products are often formed. If the chromium complex of the dye is formed from the desorbed dye in solution, this will further complicate the composition of the aftertreatment liquor. Thus reuse of mordant dyeing and aftertreatment baths is not an option. Furthermore, 100% rejection of dichromate ions would be required if the permeate of a membrane process treating the effluent was to be recycled [42]. 

Figure 10.17 shows an example of the separation efficiency of the SSF membrane for SMROG-PS A waste gas.64 It plots the rejection ( ) of the more selectively adsorbed components of the gas mixture (i = C02, CH4/CO) as a function of H2 recovery (aH2). The rejection of component i is defined by the ratio of the molar flow rate of that component in the low-pressure permeate stream to that in the feed stream. The recovery of H2 is defined by the ratio of the molar flow rate of H2 in the high-pressure effluent stream to that in the feed stream. The plot also shows the ratio of the membrane area (A) needed to process a given flow rate (F) of the feed gas. These data are sufficient to design the membrane for a given feed gas composition and flow rate.69... 

The superior flux and rejection capabilities of the thin film composite membrane has been demonstrated at the municipal wastewater reclamation facility of the Orange County Water District in California. Both asymmetric cellulose acetate and thin film composite membranes were tested on lime clarified secondary effluent. The pilot plants were operated at 85% recovery and the rejections reported in Table 4.5 are the percent rejection of the constituents in the feed-water and not the rejection of the average concentration of the specific constituents in the feed/reject stream. Use of the average concentration would give a higher rejection in both cases. 

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