Treatment of polluted surface runoff

Treatment of polluted surface run-off by constructed wetlands
Treatment of polluted surface run-off by constructed wetlands

Problem


Rainfall on farms, paved areas of biogas plants or construction waste recycling complexes produce polluted wastewater, which require a low-cost (and natural) treatment or purification. For example drive-in silos cause a highly oxygen demanding wastewater, which should be collected and used as fertilizer for agriculture. But it also delivers a surface run-off with reduced pollutant content, which is nevertheless much higher concentrated than domestic wastewater.
 

This is caused by rainfall on unsealed silage, uncovered withdrawal stocks from renewable raw materials (RRM), recycling heaps and on the transport surfaces of such materials by "crumble losses", which are mobilized by rainfall and effect a run-off. The contamination of ditches, streams or groundwater by local infiltration has been observed in many places and causes a significant legal risk (§ 324 StGB, German water criminal code) for the plant operator.

Our cleaning concept includes the following basic elements, which we had demonstrated target-oriented in projects since more than ten years.

Structure of a close-to-nature treatment cascade developed and realized by our company.



Download 1: Treatment of agricultural surface runoff - constructed wetland Hennersdorf
Download 2: Stormwater treatment wetland Eschbach
 

How occurs the treatment (purification) of highly contaminated wastewater from paved (sealed) surfaces?

Answer: Firstly by deposition process (sedimentation), but especially by microorganisms like bacteria, actinomycetes, algae, fungi. The microbiological purification process takes place:

1. in the sedimentation and the retention pond within the open water body, covered with floating islands (link),

2. in the first step of constructed wetland (vertical subsurface flow) by aerobic microbes,

3. optional, in the second step of constructed wetland (horizontal subsurface flow) by anaerobic microbes,

4. in the receiving water course (biological self-purification) or in the infiltration basin (as a further passage through a microbial, physical and chemical active top soil).
Sedimentation and storage pond (in the foreground on the right side)
covered with floating islands for treatment of silage effluents