Miljö- och hälsoskyddskontorets tillsynsarbete - ur verksamhetsövarens perspektiv
Nanofiltration is a proper way of preparation of drinking water. The process has a lot in common with reverse osmosis where a semipermeable membrane is used to separate a pure water flow from the remaining water. A pilot plant was used to ensure that nanofiltration is a suitable technology for a specific waterworks station in Glemmingebro, Ystad. The purpose was also to find out if a pH-adjustment is needed for feed water in a possible full scale plant. In this case nanofiltration is used mainly to remove sulphate and calcium since the raw water contains concentrations of these substances which exceed the limits for potable water. It is important to receive a high recovery (RC), otherwise the deliviery of water won?t be high enough. On the other hand a high RC increases the risk of precipitates, which require more frequent cleaning. An optimal RC has already been calculated, the intention of this survey is to consider whether the theory is consistent with reality or not. Calculations of the highest acceptable pH-value were made in a computer program from Dow, ROSA. The result indicates that nanofiltration is suitable to use in this waterworks station and a pH-adjustment is needed when the pH level of raw water exceeds 7.7.