The water works of Olecko in Poland was started up in May 2006. Its capacity is 190 m³/h. Raw water is first aerated in a trickling tower and some KMnO₄ is added to oxidize iron and manganese. Main objective of the subsequent sand filtration is removal of the precipitated metal oxides and reduction of the water’s turbidity. A special characteristic of this plant is that the backwash water of the main sand filter is filtered in a second sand filter. In this way the 5 % wash water ratio from the first filter is reduced to only 1 % by the second filter while the balance is clear filtrate. The plants efficiency is thus improved. Of course, the second filter also serves for redundancy. And in case that the plant’s capacity is to become increased, both sand filters can be operated in parallel.

The new water works of Kumla in southern Sweden has been in operation for about a year. Its capacity is 600 m³/h. The plant treats a blend of groundwater and surface water. Iron and manganese in the groundwater are removed by a combination of aeration and sand filtration. Colour and turbidity of the raw surface water vary within a wide range, depending on the season. Both are reduced by addition of aluminium salts.

In both cases the customers selected our CONTIFLOW® Sand Filters because of their continuous and easy operation and their low maintenance costs. Installation and start-up were done without problems and within the scheduled time frames.

By Wolfgang Fischer, Project Manager Filtration & ReUse