Of all the applications that LuminUltra works with, biological wastewater may be the most complex but also offers the greatest opportunities for cost savings and overall optimization. The greatest savings tend to come through process optimization once long-term data trends have been established but the following is a list of opportunities that present themselves immediately upon starting to generate data at a treatment plant:
1. Assess solids viability via the Active Biomass Ratio (ABR)
By conducting an ATP test on a bioreactor sample and converting the result from ng cATP/mL to mg Active Biomass/mL, it can then be directly compared to the Total Suspended Solids (TSS) for the same sample to determine the Active Biomass Ratio, ABR (%). Typically, this value ranges from 15-40% for most processes so the plant can immediately be benchmarked to determine how much of an opportunity there may be to improve this. The benefits of operating at a high ABR are many:
- Enhanced mass transfer efficiency resulting in more effective uptake of soluble BOD, nutrients, and dissolved oxygen.
- Better quality floc resulting in more effective settling
- Reduced solids handling costs due to the lack of excess solids inventory.
2. Investigate treatability of individual influent streams
Simple benchtop experiments can be conducted to assess the toxicity of individual influent streams by combining samples from these sources with mixed liquor and then comparing ATP results at the beginning and again after 1 hour of gentle mixing. ATP results that stay constant or increase indicate a benign stream while a decrease in ATP indicates toxicity. The degree of drop indicates the severity of the toxicity. Additional tests can be done over longer time intervals to investigate delayed impact as well as the population’s capability to recover.
3. Compare load balancing across multiple trains and throughout large bioreactors or digesters
For treatment plants with multiple parallel trains, samples can be drawn and analyzed from each train to assess consistency between them and possibly reveal situations where different growth patterns emerge. In situations like this, the root cause of the differences can be quickly assessed and mitigated to maximize performance.
As insightful as these exercises can be, they are just the beginning. Stay tuned for a future blog focusing on long-term benefits of ATP monitoring in a wastewater treatment plant once baseline data has been established.