BM Respirometry applied to a novel control strategy of nitrification in a wastewater biological treatment
In wastewater treatment plants, the biological nitrogen removal (BNR) has acquired critical importance, which makes that in the majority of the cases the overall process control largely depends on the control of this treatment. The normal aerobic process of nitrification is performed by specific aerobic living microorganisms and a lack of information on their bioactivity may be cause of confusion in terms of control and monitoring criteria. For this reason, the application of the BM Respirometry, for the goal of getting a determined performance within the frame of energy optimization, has achieved an important role for essential information about the actual nitrification situation but also in other situations under different conditions for the process development.
The nitrification processes control must be based on a sufficient removal substrate rate to fit the actual hydraulic retention time of the biological reactor available for nitrification: Nitrification rate = ammonium-nitrogen uptake rate (AUR)
Either the nitrification rate is the correct on which the process has to run, the plant operator should find its value. He also has to know if it is enough or not; and in case of not enough, he has to find out the causes and the possible solutions.
For that purpose, a BM respirometer can be the perfect instrument to measure the actual nitrification rate and also to analyze if this has a higher or lower value than it is required in any specific process. By other side, assuming that we cannot control de pH and temperature, the nitrification drivers are the dissolved oxygen and the sludge age (SRT) and these parameters should be well determined within the frame of the energy optimization.
2. BM respirometer
BM respirometers series include three main models: BM-T+, BM-EVO and BM-Advance.
Any of those can perform the application of the nitrification control; but, because of the pH control feature in the BM-Advance, it is probably this model the most indicated for it.
2.1. Main BM-Advance features
- Compact analyzer, with very low maintenance and user friendly operation
- Direct oxygen measurements from a maintenance-free oxygen sensor
- No oxygenation restriction during test performance
- Full control and results by means a powerful software already loaded in the PC
- Automatic software update versions from internet
- Capacity for test conditions setting and modify them throughout the test performance.
- Three different operation modes: R, OUR and Cyclic OUR
- R mode: Modified LFS system - Automatic measurements of Rs (exogenous respiration rate), CO (consumed oxygen), bCOD (biodegradable and readily biodegradable COD), U (COD utilization rate) and q (specific U)
- OUR mode: LSS system - OUR (oxygen uptake rate) & SOUR (specific OUR)
- OUR cyclic: Cyclic LSS system - OUR & SOUR within a continuous sequential chain of measurements