Field: Sustainable water cycle
Global Technical function: Separating
Technical Function Unit: Bio filtrating, Chemical separating, Cleaning, Cooling
Geographic Area: Germany

Ozone-AOP (Xyleminc)

AQUAFIT4USE is a large-scale project funded under the 7th Framework Programme
(FP7), a grant funding programme of the European Commission which aims to make industries more independent of the supply of water for their production processes. The initiative aims to develop new technologies, tools and methods as well as to apply new combinations of existing technologies for sustainable water supply, use and discharge in the main water consuming industries: in other words “water fit-for-(re)use”. These new techniques encompass innovative technologies or applied technologies dealing with water looping in the four following industries: paper, food, chemistry and textile.

In this context, an Advanced Oxidation solution, using mainly Ozonation (Ozone/AOP), has been developed by Xylem Water Solutions (Germany) as part of an innovative and integrated train-concept treatment. This chemical separating technology is performed in combination with flocculation and biological pre-treatment to oxidise various organic target compounds that are themselves not biodegradable.

Industrial waste waters can contain a broad spectrum of unwanted contaminants. A significant part of these substances consist of potentially persistent organic compounds. These cause build-up of significant amounts of residues, typically refractory COD, intensive colouration or unpleasant odour.  Contaminated industrial water, as described here, is preventing water-reuse, -recirculation and generally requires the application of cleaning methods. Ozone is a very powerful treatment option as a feasible and suitable way to address these issues with cost-effectiveness, efficiency and sustainability. The main strength of ozone is being a powerful multifunctional oxidant providing simultaneous contaminant treatment: such as disinfection, colour reduction, reducing chemical oxygen demand (COD) and elimination of endocrine disrupters (e.g. PCBs, phthalates, pesticides). Due to its nature and short half-life, ozone is generated on site from oxygen. The typical ozone system comprises oxygen/air supply, ozone generator, cooling system, ozone destructor and a power supply.

The electrode, the core element of the ozone system, enables the achievement of a level of reliability and energy-efficiency which is unattainable with most other electrode technologies. The distinctive feature of this electrode is its unique double discharge gap. Ozone is formed on both sides of the dielectric, therefore lowering the applied specific energy and increasing ozone production. This feature is one of the performance factors of the ozone generator.

Ozonation is particularly compliant with a sustainable water cycle achievement when used in combination with complementary processes in a treatment train, starting with a separating treatment step (such as coarse filtration, flocculation, flotation) to precipitate soluble and insoluble compounds, and followed by a biological treatment step and by the ozonation process. Finally, a bio filtrating treatment is reducing the biofouling potential of the treated water. In case that the salt content of the potentially re-used water is an issue, membrane technologies (as Nanofiltration or Reverse Osmosis) have to be considered.

The oxidation technique, which has been developed, is a turnkey system so that it can be readily implemented even in retro-fit scenarios. Thus, its technology readiness level is classified to be 9 on the TRL scale.