Environmental benefits – articles


Environmental benefits – articles

The development in Denmark has shown that drainage of surface water from rooftops, etc., for rain and wastewater pipes is a less environmentally friendly solution than if the green method of seepage into the ground is followed. The development has also shown that larger and more intensive rain showers will become frequent because of climate change and that towns and cellars may flood because of overloaded wastewater pipes. This is why many municipalities, with their wastewater planning, are planning to channel as much rainwater as possible back into the groundwater.

Since rain water is not always clean it may mean that polluted water flows into the groundwater. This is why it is important to choose the correct type of rain water drywell.

The BIO-BLOK® range from EXPO-NET was originally developed for cleaning wastewater because of the blocks’ large surface area which provides good conditions for microorganisms which cleanse the water biologically. The BIO-BLOK® rainwater drywell is thus a natural choice for ensuring that our rain water is converted to high quality groundwater. Not only do we ensure that the rain water goes back into the ground but also that it becomes cleaner.

The reason for this is that the BIO-BLOK® drywell is made of net tubes, which together make up a very large surface area which forms an ideal habitat for microorganisms. As soon they are in contact with the diverted water, these microorganisms will immediately start to break down the organic pollution which at times can be found in the surface water.

A BIO-BLOK® 80 HD G with a biofilm surface of 1 mm will have a biologically available surface of approximately 165 m2/m3 drywell. With a turnover of approximately 1 g BOD/m2 per 24 hours this will lead to a total BOD reduction of 165 g/day x m3, which is equivalent to waste water pollution from two people over 24 hours.


EXPO-NET has prepared a couple of articles relating to this subject. Click on the icons below to download these articles:

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Separation of combined sewage areas
with dense populations (only in Danish)

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Drainage of rainwater - a tool in
municipal wastewater planning
(only in Danish)