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Objectives

The implementation of large-scale ozonation for demonstrational purposes and for the treatment of the entire combined sewage inflow is a project funded by the NRW.Bank. In addition to ozonation, removal efficiencies of secondary clarifiers will be improved and clearwater nitrification will be optimised for follow-up treatment of ozonation. 

Investigations carried out within the reserach project DemO3AC are funded by the Ministry for Climate Protection, Environment, Agriculture, Conservation and Consumer Protection of the State of North Rhine-Westphalia, Germany. They include issues for desgin, process technology, operational as well as water quality aspects. Objectives are: 

  • Monitoring of the status quo before implementation of ozonation of both WWTP and river Wurm and the effects treated wastewater has on organisms; tested on both organisms in the laboratory (biotests/ecotoxicity) and in situ
  • Ozonation of the entire combined sewage inflow and chemical, biological and ecotoxicological investigations (e. g. endocrine disruptors, genotoxicity, mutagenicity...) of the treated wastewater in comparison to the investigations "before ozonation". 
  • Optimization of ozone production, gas application, water flow and cooling of aggregates regarding an economical operation of ozonation in the sector of municipal wastewater treatment.
  • Evaluation of a realistic cost-benefit analysis. 
  • Development of a biotest battery taking into account findings of other projects, e. g. projects from Switzerland like Micropoll, but also PILLS, EDA Emerge, SOLUTIONS, ToxBox, the NORMAN Network of reference laboratories, research centres and related organisations for monitoring of emerging environmental substances and latest insights of the Technical Report on Effect-Based Tools presented at the Meeting of Water and Marine Directors of the European Union, Candidate and EFTA Countries in Vilnius.

In particular: 

  • What recommendations can be derived regarding planning and design on the basis of existing large-scale ozonation plants?
  • What kind of investigations are necessary and advisable for the planning stage?
  • Which reactor design is suited for the elimination of micropollutants in wastewater? Are the approaches to apply reactor designs from the drinking water treatment (multiple feed systems) still sustainable?
  • Which control concept for ozone feed allows the most precise dosage in terms of micropollutant elimination? Are there control concepts or parameters qualified for an indirect process control?
  • Is the biological follow-up treatment essential for a safe process in terms of (eco-)toxicity or is an additional reaction chamber sufficient?
  • What impact does the ozonation have on the day-to-day operation of the WWTP?
  • Is the mechanical engineering reliable in relation to long-term operation? Is a redundant design for certain aggregates necessary? 
  • Which measures can be took for energy saving?
  • Which input system is most suitable for the elimination of micropollutants and what influence does it have on the development of metabolites (e. g. bromate, NDMA)?
  • Does a reduction of micropollutants have a significant impact on the improvement of the water biocenosis/water quality? Is it possible to quantify these effects?

The project is divided in two phases of two years each. Within the first phase, the status quo of the emissions from the WWTP and the receiving water before implementation of ozonation are investigated. It also includes groundwork for the design of the large-scale ozonation plant using a pilot-scale plant. 

Phase two then deals with the commissioning of the large-scale plant and the evaluation of its effects on the WWTP and the receiving water. Several modes of operation will be investigated to not only eliminate micropollutants, but also for disinfecition purposes of a partial flow.