As a result eutrification (the process in which oxygen is removed from the water by the decomposition of large amounts of organic matter) the water quality in the Denis Pond in Woluwe Park, Brussels, Belgium began to deteriorate in the 1960’s and accelerated in the 1970’s. This eutrification resulted in a reduction in water transparency, an increase in the production of organic substances, composition of species changes (perennial algae are replaced by annuals, such as blue-green and green algae, the composition of benthic species is depleted, the food base for fish changes and correspondingly so does the composition of fish species), rapid choking of water courses with vegetation takes place, and the smell of decomposition begins to spread.
The deterioration of the pond impacted on the fish population with all carnivorous species dieing out. Only species like roach (Latin: leuciscus rutilus) were able to grow and thrive under the deteriorating conditions. Bottom-feeding specise such as carp (Lat. carpa) and tench (Lat. tinca vulgaris) were only able to survive because of supplemental feeding. Analysis of dead fish confirmed that mortality in the pond was the result of a lack of oxygen or the build up of toxic compounds such as NH3 or S=.
Because of the pond’s location in the centre of the Woluwe Park and its unappealing appearance and odor, a decision was made to try and restore the pond to its original condition. It was felt that some form of unobtrusive treatment was preferred so as not to disrupt public movement and flow through the park.
Nordevco’s BactiDomus® Technology was selected for use in the remediation of the Denis Pond because of its ease of application and the complete lack of impact on the public’s accessibility to the pond during the treatment.
The treatment was carried out by Nordevco Associates Ltd’s European research partners. Two applications of Nordevco’s BactiDomus® Technology product designed for remediation of water bodies were carried out over a four month period in 1990/91. In both applications, the product was applied directly over the surface of the pond (see photo below)
Treatment of denis pond woluwe park brussels, Belgium case study