Case study: Municipal Water Treatment at George Municipal water works in South Africa Water Treatment
Follows is a short report on the trial using DMI 65 vs. conventional silica sand at George Municipal water works. Please note that the DMI 65 filter had new nozzles fitted to allow for the finer sand. All filters are Degremont design. George water is highly coloured containing Humic and Fulvic acids – the raw water colour is approx. 800 PtCo colour units. This type of water is believed to be one of the most difficult to filter. The plant has been running since the beginning of January 07 and we continue to have excellent results.
Report on DMI 65 trials at George Municipality:
It appears that iron removal is very effective regardless of the pH. The highest residual iron found was 0.01 mg/l. (SANS 241 requires less than 0.20)
Manganese removal is also very efficient. The highest remaining manganese found was 0.06 mg/l (SANS 241 requires less than 0.10) which occurred after problems with the flocculation process and at a high pH. Further investigation is needed to determine optimum pH for manganese removal.
Aluminium tests were only done once on 13 December and we found 0.03 mg/l. (SANS 241 requires less than 0.30). It seems that we are getting an additional benefit of aluminium removal even at the higher pH.
After the first 48 hours of operation the highest turbidity recorded was 0.06 NTU. (SANS 241 require less than 1.0) It has been noted that during the flocculation problems, the quality of the water after filtration through the DMI 65 remained very good while the filters with normal sand were back-washed repeatedly.