THE PROBLEM
The plant is receiving TKN to the tune of 70 ppm and due to new discharge standards for municipal wastewater treatment, the Ammonia in the outlet is required to be reduced to < 5 ppm and TN < 30 ppm. Due to this being an island country, the authorities operating the plant have severe space restrictions and thus a solution which helps them to achieve a desired level of nitrification within the same infrastructure without additional civil construction and land requirement is a highly sought after solution.
- Existing BOD removal plant Having high TKN load of 70 ppm
- Requires outlet Ammonia < 5 ppm and TN < 30 ppm
THE SOLUTION – Upgrade of Activated Sludge
Based on our extensive experience with cold weather nitrification using the Levapor IFAS process, a solution was proposed to utilize two of the first reactors of the cascade as suspended growth reactors while the last two reactors would be converted into a Levapor carrier based IFAS reactor with a volume fill of 11% of Levapor product.
Proposed Solution:
- Use two first reactors of the cascade as suspended growth reactor,
- Two last reactors were upgraded to Levapor IFAS reactors by adding carriers at 11% fill.
The solution proposed was tested in a pilot process configuration and the results were confirmed at site for its efficacy to achieve desired level of nitrification as per client’s requirement.
Levapor IFAS process pilot plant at site Full scale plant modification – two IFAS reactors
After successful trials, the project was implemented with minimal modifications involving:
- Retention screen placement for the IFAS reactors
- Rearrangement of diffuser grid to meet air requirement for nitrification and IFAS reactor mixing requirement.
THE RESULTS
The plant is achieving consistent nitrification to Ammonia < 5 ppm level and COD < 30 ppm at the outlet with much lower down time for the process start up and upgradation.
THE BENEFITS
- Minimal changes to existing infrastructure.
- Quicker implementation and process start up after upgrading has occurred.
- Achieving consistent level of Nitrification even with less than 6 hours HRT for cold climate Quick startup of the process and stabilization.