Improved treatment performance
Model simulations of Viby WWTP operation with optimised process configuration showed significant improvements when compared to both current operation and other configurations tested, particularly:
- High effluent quality even under increased loading conditions (nitrate < 6 mg/L, total phosphorus < 0.25 mg/L)
- Reduced chemical consumption (< 200 kg/d for both external carbon and FeCl3)
Up to 47% reduction in effluent taxes was estimated to be achievable through the optimised operation, leaving considerable room to overcome costs for chemical usage and equipment installation.
Full-scale application of new operational strategy
At the end of 2019, the new operational strategy was implemented in Viby WWTP. A comparison of the treatment performance before (March 2019) and after the capacity expansion (March 2020) is presented in Figure 2. Despite significantly higher influent flow, the reported measurements indicate similar, if not improved, effluent nitrate and ammonia levels in 2020. Specifically, more efficient denitrification was achieved by implementing the advanced control strategy and increasing sludge retention in the system, as shown by improved settling characteristics (Figure 3).
Overall, the proposed solution for capacity expansion has provided tangible improvements in the performance and operational stability of Viby WWTP while proving to be cost-efficient and reducing the need of preliminary full-scale testing.