The idea of constructing a wastewater treatment plant for the areas of the then municipalities of Domžale and Kamnik was born before 1975 and then in July 1975 a document entitled » Study of Industrial Wastewater in the Towns of Domžale, Kamnik, and Mengeš« was drawn up by the Institute for Water of the Republic of Slovenia for the purpose of making this idea a reality. Due to its developed and diverse industry, the area of Domžale-Kamnik was already at that time one of the areas in Slovenia potentially mostexposed to pollution. However, the care and efforts of our forerunners in the field of river protection resulted in the beginning of the construction of the Domžale-Kamnik Central Wastewater Treatment Plant in 1975. The construction itself was funded not only by the state, but also by the biggest water polluters in the area, and the then and current municipalities of Domžale and Kamnik as the owners of the Domžale-Kamnik Central Wastewater Treatment Plant (hereafter referred to as the CČN).
The current workload of the CČN, which is treating municipal wastewater, rainwater and industrial wastewater from the areas of the municipalities of Domžale, Kamnik, Mengeš, Komenda, Cerklje na Gorenjskem, and Trzin, ranks this plant as the fourth biggest municipal wastewater treatment plant in operation in the Republic of Slovenia. With the upgrade in 2016, nitrogen and phosphorus removal units were added to the plant. The treated wastewater is released into the Kamniška Bistrica, a mountain river with a fast current which flows into the Sava river.
|Chronology of the Development of the Domžale-Kamnik CČN:|
|Construction of the sewer network||1972–1975|
|Construction of the treatment plant||1975–1980|
|Launch of the CČN (without anaerobic digestion and a sludge dumping ground)||1981|
|Modernization of the treatment plant||1981–2000|
|Construction of the wastewater dehydration system||1986|
|Digesters for Stage II||1991|
|Power supply building||1993|
|Facility A - skimmers||1990|
|Change of the ventilation system||1999|
|Mechanical treatment: sludge skimming optimization||1999|
|Old digestors, capacity expansion of the heating system||1999–2000|
|Renovation of the primary sedimentation tank||2003–2004|
|Change of biogas engines||2004|
|Upgrade of the CČN (renovation of the entry building; construction of new SBR basins, a discharge facility; setting up SBR deammonification)||2014–2016|
|Beginning of trial operation||19. 12. 2016|
The most important part of the upgrade was to build a new aerobic biological stage during which nitrogen and phosphorous compounds, in addition to carbon compounds, are removed. Thus the CČN was able to comply with the legal requirement of including the teritiary treatment in the process.
The CČN must replace a large part of its equipment in the coming years. The investments will include the change of the biogas engine for producing electricity. Furthermore, additional wastewater reception from the areas where the sewer system is still under construction, more precisely from the current reception municipalities as well as from the municipality of Cerklje na Gorenjskem, will be made possible. The infrastructure for the additional wastewater reception includes an equalization basin which holds water surplus in case of heavy downpours. With the upgrade completed, the levels of organic matter as well as of nitrogen and phosphorous in the Kamniška Bistrica have been lowered substantially, which will be reflected in improved chemical and biological conditions in the river.