Induced bank infiltration

General features

River bank (and lake bank) filtration is applied as a source for drinking water production in Europe for more than a hundred years. Since 1950, increased contamination of surface waters with persistent organic compounds threatened the use of bank filtration. However in recent years, due to the success of effective control measures and a decrease in industrial pollution together with installed monitoring programs, bank filtration has again become a reliable resource for raw water abstraction.

 

Induced bank infiltration is practiced on different scales, but generally they are complex, large scale and high cost projects. In the Rhine basin alone, more than 20 million inhabitants receive drinking water which is directly or indirectly prepared from river water, mostly via bank filtration. At a smaller scale bank filtration is used for rural and small town water supply, also in developing countries. Bank infiltration schemes are usually managed by (municipal) water authorities.

 

The biggest advantages of induced bank infiltration schemes are that large amounts of groundwater may be abstracted from wells or galleries without serious adverse effects on the groundwater table further inland. Also particles, bacteria, viruses, parasites and easily biodegradable compounds are removed, and concentrations of persistent organic contaminants and heavy metals reduced in the filtration process.

 

Disadvantages are that the surface may need to be scraped during periods of low water level, if clogging of the river or lake-bed is excessive. Long term contamination of river water by persistent organic compounds (such as pesticides and pharmaceuticals) may contaminate the groundwater, and is therefore currently the biggest threat to induced bank filtration schemes.

 
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