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• I X-FLOC The XIGAT"" Concept and Operation Manual During the CEB it is important that the first backwash without the chemicals will remove most of the foulant prior to the backwash with added chemicals. In this way the chemicals are exposed only on the -hard to remove-foulant. It is also important that the whole vessel is filled with chemicals, in the correct amount and with the correct soaking time. After soaking it is important to flush all the chemicals out with a backwash and, as mentioned in the backwash procedure, the TMP during CEB may not exceed 3 bar with a flux rate of 250-300 I/m2h. The chemicals to be used in the CEB depend on the type of foulant to be expected from the feed water. e.g. HCL/H2O2 (pH=2/200 ppm) in a sandfilter backwash water from a ground water source application containing mainly ironhydroxide and manganeseoxide. Or e.g. NaOCI (100 ppm) in a pre-treated surface water application. Chemical Cleaning If despite all preventative measurements (Backwash and Chemically Enhanced Backwash) the TMP rises above 1 bar then additional Chemical Cleaning with different chemicals is recommended. Also for disinfectants it is recommended that e.g. once every month the system is cleaned with a different disinfectant as used in the CEB. The most effective chemicals to be used in this additional Chemical Cleaning depend on the type of foulant in the feed water and the chemicals used in the standard CEB. Example 1: The chemical used in CEB is HCL/H2O2 and the foulant is mainly biological growth. A chemical cleaning via the backwash using 500 ppm NaOCI can be performed in 3-4 sequences with a soaking time of 15 minutes each time. Example 2: The chemical used in CEB is NaOCI and the foulant is mainly metal salts. An overnight soaking in HCI (pH=2) or 1% citric acid could be considered. E R� C 8 nllrelion ome ,t t�1 %!` erabg nm iMP E t m 1ti rr,e,,,�i�arynq time CAPF-XIGA-0143