Often the concern is the potential impact on ammonia oxidizing bacteria (AOB), which are much more sensitive and slower growing than heterotrophic microbes. Many compounds are highly toxic to ammonia oxidizing cultures including:
- Heavy metals (Cu, Co, Pb, etc.)
- Certain Halogenated Compounds
In order to determine the potential impact on ammonia removal, we can do a simulation using a concentrated Nitrosomonas culture. There are three basic toxicity screening tests we can do using a syringe of Nitrosomonas cell paste.
- Dilute new stream to see immediate untreated toxicity to culture
- Simulate treatment with existing heterotrophic cultures in a shake flask simulation. Then test with the Nitrosomonas procedure.
- Test the whole effluent toxicity using Nitrosomonas as a proxy for acute toxicity higher life forms such as ceriodaphia dubia. This requires correlating AOB inhibition to acute and chronic toxicity testing by running samples during the same period.