The addition of Degrémont Technologies-Ozonia’s AQUARAY® Ultraviolet units will upgrade 2 ozone plants for the city of Paris and bring them to full compliance.
With a capacity to treat 2 x 300 000 m3/day of drinking water, the project is the largest drinking water UV contract in Europe.
Pathogen removal and bromate concentration reduction
Levels of bromate ions in drinking water have recently come under scrutiny. These are commonly formed by the reaction between ozone and bromide ions, which are naturally present in water.
However, the addition of UV disinfection units to ozone treatment plants ensures that only the safest and highest quality of water is delivered, and well under limits imposed by new regulations on pathogens and bromate ions:
• The AQUARAY® H2O UV reactors act as a final barrier in the disinfection process by inactivating pathogenic microorganisms like viruses, bacteria and parasites. UV lights are particularly effective for chlorine-resistant microorganisms such as Cryptosporidium and Giardia, even at low doses.
• UV treated water fully meet the new maximal limits of bromate concentrations, which were lowered to 10 μg/l (from 25 μg/l) in December 2008.
The challenge: retrofitting the plant with UV reactors while maintaining full operation of the existing lines.
Degrémont and Degrémont Technologies-Ozonia were selected not only for the efficiency of their AQUARAY® H20 ultraviolet water disinfection reactors but also because of their long experience and ability to retrofit existing sites while maintaining full operation.
Careful consideration was given to the design and modeling of the UV reactors in order to guarantee compliance with the project’s specifications and to the development of an installation plan that would keep the operation of the treatment lines already in place intact.
The project consists of:
• Replacing the regulation valve,
• Adding a shut-off valve,
• Installing the UV reactors in the existing plant while minimizing head loss, after a functional analysis of the filters/UV reactor combination,
• Guarantying a dose of 40 mJ/cm2, under the most unfavorable conditions (maximum flow, minimum transmittance).
After validation of the specific operating conditions at the Orly and Joinville sites by DENARD (Degremont North America Research and Development) , Degrémont Technologies-Ozonia developed highly-advanced hydraulic modeling parameters (based on Computerized Fluid Dynamics (CFD) using 'Fluent' software), in order to precisely calculate and quantify the effects of hydraulic disturbances and pressure losses.
This preliminary study demonstrated without a doubt that installation of AQUARAY® H20 UV water disinfection reactors would have no significant impact on the hydraulics of the plant and that given the low pressure losses, they could be easily retrofitted to the main piping system, at the outlet of the activated carbon filters.
The study also established the DN 500 diameter as the most appropriate choice for the plants. The reactor/valve combination guarantees the specified head loss and the performance of the hydraulic regulation.
”The CFD modeling step was crucial and confirmed that our UV reactors could be installed without any negative impact on the activated carbon filters. The technical teams of Eau de Paris and Degrémont greatly contributed to the success of this project through active collaboration” said Vincent Pilmis, Project Manager for Degrémont Technologies-Ozonia.
AQUARAY® H20: State- of- the- art UV medium pressure reactors
Proven and recognized
UV treatments do not alter the physicochemical characteristics of the water. BIOASSAY, or biological tests, conducted on specific organisms in an operating plant provide the only ultimate validation of the effectiveness of the UV treatments.
The AQUARAY® H20 UV water disinfection reactors (20' Mono and 20' Duplex) are certified by the German Technical and Scientific Association for Gas and Water (DVGW) and the US Environmental Protection Agency (EPA), and guarantee consistent compliance with the prescribed amount of 40mJ/cm² defined in conjunction with the Paris Water Management company.
In addition, in France, when used to prevent parasitic risks, UV treatment solutions must be approved by the French Ministry of Health.
Currently, Degrémont Technologies-Ozonia is the only manufacturer to have obtained this approval for this specific range, following a recommendation from the French Food Safety Agency (AFSSA) to manage the flow rates such as those treated by its AQUARAY® H20 20' Mono and 20' Duplex range.
High performance and reliability in a small footprint
The AQUARAY® H2O inline cross flow reactors use high density medium pressure lamps to offer a compact footprint and reduce capital costs.
Engineered with advanced CFD modeling software to determine the optimal lamp spacing, the system provides consistent and reliable disinfection with a minimum of head loss.
The powerful dose of UV light delivered requires fewer lamps (only 6 UV lamps by reactor for Joinville and 12 lamps for Orly to achieve a production of 300 000m3/day) and significantly decreases operating and maintenance costs.
The medium pressure lamps are powered by electronic ballasts. The lamps are inserted in pure quartz sleeves isolating them from the water. The lamps can be easily changed without draining the reactor and, due to the electronic variable output ballast, the total power can be adjusted on demand. Moreover, a dedicated and calibrated UV sensor is installed for each lamp to monitor the UV intensity and ensure optimum reliability.
The AQUARAY® H2O offers a compact footprint and easy integration in new or existing water treatment lines and the easy access to all components ensures rapid and trouble-free maintenance.