SUEZ demonstrative project in Brædstrup, Denmark
Many micropollutant present in municipal wastewater, such as pharmaceuticals and pesticides, are poorly removed in conventional wastewater treatment plants, and may generate adverse effects on aquatic life and contaminate drinking water resources.
To reduce the release of these substances into the environment, advanced treatments are necessary. Removal of micropollutant by application of multiple point ozone injection and integrated PAC are the innovative solutions by SUEZ that is demonstrated in Brædstrup wastewater treatment plant, Denmark.
About this project
This project is to demonstrate a new and cost-effective solution for Micropollutant removal that enable Micropollutant removal to be built on any medium or large wastewater treatment plant.
The purpose is to demonstrate a new and cost-effective solution for Micropollutant removal that enable Micropollutant removal to be built on any medium or large waste water treatment plant for a total cost of ownership of max. 3 €/person per year, which we claim is 50% cheaper that existing solutions in small hospital flows today.
New important knowledge on how the ozone should be applied to the clarified and into recycled mixed liquor by development of dosing equipment, injectors and monitoring equipment are gathered from the project and the effect on the effluent quality are demonstrated.
The project is partly funded by Miljøteknologisk Udviklings- og Demonstrationsprogram (MUDP) in Denmark.
Why?
In recent years there have been an increasing focus on micropollutants in wastewater. Especially, the need/focus on removing pharmaceuticals from the new big hospitals (super sygehuse) in Denmark and the subsequent usage of decentral cleaning solutions have been debated. Hospitals use rather big amounts of pharmaceuticals when treating patients and one would think that hospitals subsequently discharge the largest overall pharma quantities to the wastewater. However, more and more studies suggest that is not the case, simply since patients often are treated as outpatients. The patients therefore discharge pharmaceuticals at their own house, sending it through the municipal sewage systems to the local wastewater treatment plant. Studies have found hospitals to account for approx. 4% of the total pharma load, while the remaining 96% comes from regular households. But as it is right now, municipal wastewater treatment plant are not geared to handle MPs.
Objectives
- The proof of concept for multiple ozone injection to remove MP, deep analysis of MPs removal efficiency in full scale
- Demonstrate Total Cost of Ownership (3 €/person/year) of the Micropollutant removal concept.
- Demonstrate the positive nexus between ozone application and the biological treatment:
- MP removal from sludge and effluent
- Enhanced SVI & Bulking control
- O2 needs contribution & disinfection
- Low additional cost for 2 (+10% app.)
To apply PAC into conventional activated sludge and demonstrate its effectiveness to reach effluent requirement.
Project organization chart
Timeline
Experimental programme
Test and demonstration will be conducted on 2 parallel wastewater streams with the same wastewater characteristic – one will be tested with and one without the applied MP/Ozone/PAC technology.
Mixed liquor ozonation + Tertiary ozonation
- Ozone is injected in an independent recycling loop with pumping and restitution into the aeration zone of the OCO-like process.
PAC injection into the mixed liquor
- Powder Activated Carbon (PAC) will be prepared with drinking or industrial water, flocculated with FeCl3 and then injected into the aerated zone of the OCO-like process.
Test phases
In a comprehensive experimental program, first the performance of conventional activated sludge inMicropollutantremoval has been evaluated in Brædstrup WWTP for 39 selected compounds. Test and demonstration are performed at full scale on one of two parallel wastewater streams with the same wastewater characteristic – one will be tested with and one without the applied Ozone or integrated PAC technologies, in 2 phases.
In phase 1, ozone is applied continuously in 2 points: in aeration tank by using venture ejector and in outlet of secondary clarifier by using the dome diffuser in an ozone contact tank, with total 11 mgO3/L distributed in two points, for total duration of 10 months. The test started in March 2019 and ends in October 2019.
In phase 2, which lasts for 4 months starting from November 2019, consists of adding PAC Norit SAE Super continuously to aeration tank in 5 and 10 g PAC/m3.
Pre-screening
- The pre-screening helped us understand and figure out which micropollutants are present at Brædstrup wastewater treatment plant. In total over 350 compounds were tested for. Of those we narrowed it down to just below 40 compounds by selecting/combining the Danish AMK list (DHI guideline list), the Swiss indicator list and the watchlist from EU.
Baseline
- Then in the fall of 2018 the baseline test was performed on those selected compounds, and the presence and concentration of different pharmaceuticals/micropollutants was identified. The baseline also showed the two lines at Brædstrup Wastewater treatment plant to be comparable
Phase 1 – Multiple point ozonation
- Condition 1
Spring – summer 2019 (duration: 110 days) - Mixed liquor ozonation (process tank) – 4.00 mgO3/L
- Tertiary ozonation (after secondary clarifier) – 7.00 mgO3/L
- Condition 2
Summer – fall 2019 (duration: 110 days) - Mixed liquor ozonation (process tank) – 7.00 mgO3/L
- Tertiary ozonation (after secondary clarifier) – 4.00 mgO3/L
Phase 2 – PAC (Powdered Activated Carbon)
- Condition 1: Started 1st of November – 5 mgPAC/L
- Condition 2: Starting January 2020 – 10 mgPAC/L
According to the experimental program, target analytes were extracted from raw wastewater, treated wastewater and sludge extraction lines. The efficiency of applied technologies is evaluated compare to biological activated sludge process. Meanwhile, all the costs expended to implement both multipoint ozonation or integrated PAC application including investment cost as well as operation costs including electricity and reagents are documented.